Objective: Although pancreatic cancer has an extremely high case fatality rate, little is known about differences in mortality by histologic types. We examined median survival and risk of mortality for endocrine pancreatic tumors and two types of exocrine tumors, adenocarcinomas, and mucinous tumors.

Method: This analysis included 35,276 pancreatic cancer cases reported to the nine population-based cancer registries participating in the Surveillance, Epidemiology, and End Results program from 1973 to 2000. Survival among cases with pancreatic adenocarcinomas, mucinous tumors, and endocrine tumors were compared using Kaplan-Meier plots. Comparative risks of mortality were evaluated using multivariate adjusted Cox regression models.

Results: Endocrine pancreatic cancer cases had a median survival of 27 months compared with a median survival of 4 months for adenocarcinoma and mucinous tumor cases. Compared with adenocarcinoma cases, endocrine tumor cases had a 0.28-fold lower risk of mortality [95% confidence interval (95% CI), 0.26-0.30], and mucinous tumor cases had a 0.88-fold lower risk (95% CI, 0.84-0.91). These results were similar for men and women. Within histologic types, advanced tumor stage, older diagnosis age, surgery, and Black race were associated with increased risks of mortality, whereas female sex and more recent year of diagnosis were associated with decreased risks.

Conclusion: This study confirms the clinical observation that patients with endocrine pancreatic cancer survive longer than patients with exocrine tumors. A better understanding of these differences could contribute to identifying the underlying causes of pancreatic cancer and to improving survival rates across all histologic types.

Pancreatic cancer is a leading cause of cancer mortality in the United States; it is the fourth and fifth most common cause of cancer death among men and women, respectively (1). Although several risk factors for pancreatic cancer have been identified, including smoking (2), age (3), family history (4), and diabetes (5), this knowledge has not led to substantial improvements in the early detection or survival of pancreatic cancer cases (6). In addition, most studies of pancreatic cancer survival focus on survival after surgery and are thus not generalizable to all cases.

Similar to cancers arising in other organs, pancreatic tumors are classified according to their cell type of origin, structure, and behavior. The pancreas is a multifunctional organ consisting of a variety of cell types (6). The exocrine pancreas is comprised of duct cells and acinar cells that produce a combination of gastric enzymes needed for digestion (7). In contrast, the endocrine pancreas contains β cells and other types of endocrine cells that produce hormones, including insulin, that are dispersed throughout the body and that are required for glucose metabolism (8).

The majority of exocrine pancreatic cancers are adenocarcinomas. These tumors originate in the epithelial cells lining the pancreatic duct, form gland-like structures, and account for ∼90% of all pancreatic cancers (9, 10). Mucinous tumors, another type of exocrine pancreatic cancer, is the second most common histologic type of pancreatic cancer, accounting for <10% of all tumors. Mucinous tumors are usually less invasive at diagnosis than other types of exocrine pancreatic cancer (11). These tumors form sac-like structures, secrete mucin, and typically arise from the pancreatic ductal epithelium (11). Cancers of the endocrine pancreas are less common, occurring at a rate of about five per million person-years, and accounting for <5% of all pancreatic cancers (12). These tumors arise from pancreatic islet cells, including β cells and α cells (8). Rather than ablating endocrine function in the pancreas, these tumors often produce pancreatic hormones at high levels (13). Tumors of this type include insulinomas and gastrinomas and are often detected due to the symptoms caused by excessive hormone levels (12).

Although disparities in survival time between endocrine and exocrine pancreatic cancer have been noted clinically, these differences have not been quantified. Furthermore, survival differences among subtypes of exocrine pancreatic cancer (adenocarcinomas and mucinous tumors) have not been reported. The few studies that have evaluated pancreatic cancer survival by histologic type were not population-based and were restricted to pancreatic cancer cases receiving surgery thus limiting their generalizability (14-16). The purpose of this study was to quantify the median survival times and compare the risks of mortality for cases diagnosed with adenocarcinomas, mucinous tumors, and endocrine carcinomas of the pancreas using population-based data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program from 1973 to 2000. In addition, we sought to identify risk factors associated with mortality within each histologic type.

Case Selection

Pancreatic cancer cases diagnosed from January 1973 to December 2000 were ascertained from the nine population-based cancer registries that participated in the SEER program over this period (17). These registries serve the states of Connecticut, Hawaii, Iowa, New Mexico, and Utah and the metropolitan areas of Atlanta, Detroit, San Francisco-Oakland, and Seattle-Puget Sound. All registries contain data on cancers diagnosed from January 1973 onward, with the exception of the Seattle-Puget Sound and Atlanta registries, which contain data on cancers diagnosed from 1974 onward and 1975 onward, respectively. It is estimated that >95% of all incident cancer cases in the populations under surveillance are ascertained. Further operational details and methods used by the SEER program are provided elsewhere (18).

In total, 64,649 potentially eligible cases were identified from the SEER registries. Those with an unknown survival time (n = 2,691), a diagnosis age of <20 years (n = 32), nonmalignant disease (n = 47), unstaged tumors (n = 10,751), rare histologic types of pancreatic cancer based on their four-digit International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3) histology code (n = 1,397), or a nonspecific histology (n = 14,455) were excluded. The remaining 35,276 cases of pancreatic cancer that were included in the analysis were divided into three histologic type groups based on their ICD-O-3 codes: (a) adenocarcinomas (n = 31,357; 89% of total; ICD-O-3 codes 8140, 8141, 8143, 8144, 8190, 8211, 8261, 8262, 8263, 8290, 8440, 8503, 8560, and 8570), (b) mucinous tumors (n = 2,865; 8% of total; ICD-O-3 codes 8470, 8471, 8472, 8473, 8480, and 8481), and (c) endocrine tumors (n = 1,054; 3% of total; ICD-O-3 codes 8150, 8151, 8152, 8153, 8154, 8155, and 8246). It is worth noting that 93% of the mucinous tumor cases were categorized as mucinous adenocarcinoma or mucin-producing adenocarcinomas (ICD-O-3 codes 8480 and 8481, respectively).

Survival and Mortality Analyses between Histologic Types

Survival time was measured in months from date of diagnosis until date of death. Nondeaths were censored at the follow-up cutoff date for the SEER data set (December 31, 2000), or the date the case was last known to be alive. SEER registries obtain survival time for cancer cases by reviewing medical records and death certificates to obtain dates of diagnosis, death, and last known follow-up. Because pancreatic cancer is often fatal at diagnosis, a large number of cases had a SEER-assigned survival time of 0 month (n = 3,080; 8.6% of total), indicating that the case survived for <1 month. To minimize any bias that could result from excluding these cases from the analysis, cases with a survival time of zero were each assigned a survival time of 0.5 month.

We used Stata version 8.2 (Stata Corp., College Station, TX; ref. 19) for all descriptive and statistical analyses. To compare survival in the three histologic types, we plotted Kaplan-Meier curves for 5-year survival. The assumption of proportional hazards was confirmed using plots of the log cumulative hazards for each histologic type (data not shown). Cox regression was then used to compare risks of mortality for the three case groups and to calculate hazard ratios (HR) and 95% confidence intervals (95% CI; ref. 20). In these analyses, cases with adenocarcinoma served as the reference group.

Several potential confounding variables were defined a priori and were included in the multivariate Cox model, coded as categorical variables. These variables were age at diagnosis (<50, 50-59, 60-69, 70-79, and >80 years), year of diagnosis (1973-1976, 1977-1980, 1981-1984, 1985-1988, 1989-1992, 1993-1996, and 1997-2000), SEER historic stage (local, regional, or distant), race (White, Black, Asian/Pacific Islander, and other/unknown), SEER registry, and gender. Another measure of tumor progression, tumor grade, was not included in these analyses due to the large percentage of cases with ungraded tumors (50-79% of all cases with different histology types in this data set). Because previous studies found differences in pancreatic cancer mortality for men and women (21, 22), we tested for effect modification by gender. Gender was found to be an effect modifier of the association between histologic type and risk of mortality by likelihood ratio testing (P < 0.001), comparing a model containing a multiplicative interaction term for gender and histology with a model without the interaction term. Thus, the mortality analyses were repeated stratified by gender.

Mortality Analyses Stratified by Histologic Type

We used Cox regression to identify risk factors associated with mortality within each of the three histologic types. The risk factors examined were tumor stage, age at diagnosis, calendar year at diagnosis, gender, and race in multivariate adjusted models, using the definitions of covariates provided above. Test for trend analyses for ordered variables (tumor stage, age at diagnosis, and calendar year at diagnosis) were done using grouped linear variables in the multivariate-adjusted models.

Analysis of Surgery Subgroup

Given the generally short survival time of pancreatic cancer, cases that survive long enough to receive surgical treatment are highly selected and are thus not likely to represent all pancreatic cancer cases. However, for comparison with other studies, we conducted an analysis of the association between surgery and pancreatic tumor survival. The three surgery classification groups included in the analysis were (a) any partial or total pancreatectomy, including the Whipple procedure (ref. 6; a total or partial pancreatectomy with a subtotal gastrectomy and duodenectomy, either with or without a splenectomy); (b) other cancer-directed surgery (including local excision of tumor); and (c) no cancer-directed surgery or no surgery (including cases who only received biopsies). HRs were calculated comparing recipients of pancreatectomy and other cancer-directed surgery with patients who did not receive surgery. Subjects with an unknown surgery status (n = 14,692) were excluded from this analysis.

Demographic characteristics of the three pancreatic cancer histologic types are presented in Table 1. The mean age at diagnosis was similar for both adenocarcinomas and mucinous tumors (67.3 and 66.7 years, respectively), whereas endocrine tumor patients had a somewhat younger mean age at diagnosis (58.0 years). In general, the number of cases diagnosed with each histologic type increased over the course of our study. Nearly equal numbers of women and men were diagnosed with mucinous tumors, whereas more men than women were diagnosed with endocrine tumors and adenocarcinomas. Distributions by race were similar within histologic types, although a slightly lower proportion of endocrine tumor cases were Black. In general, the proportion of cases with each histologic type were similarly distributed throughout the SEER sites. Distributions of localized, regional, and distant tumor stages were also similar within each of the three groups, with more than two thirds of the cases having distant disease.

Table 1.

Demographic characteristics of pancreatic cancer cases by histologic type

Adenocarcinoma (n = 31,357)Mucinous tumors (n = 2,865)Endocrine tumors (n = 1,054)Total (n = 35,276)
Age at diagnosis n (%) n (%) n (%) n (%) 
    <50 2,472 (7.9) 261 (9.1) 317 (30.1) 3,050 
    50-59 5,776 (18.4) 514 (17.9) 240 (22.8) 6,530 
    60-69 10,027 (32.0) 972 (33.9) 266 (25.2) 11,265 
    70-79 9,514 (30.3) 840 (29.3) 187 (17.7) 10,541 
    80+ 3,568 (11.4) 278 (9.7) 44 (4.2) 3,890 
    Mean (SD) 67.3 (11.3) 66.7 (11.4) 58.0 (14.6) 67.0 (11.5) 
Year of diagnosis*     
    1973-1976 3,078 (9.8) 306 (10.7) 85 (8.0) 3,469 
    1977-1980 3,959 (12.6) 384 (13.4) 106 (10.0) 4,449 
    1981-1984 4,451 (14.2) 382 (13.3) 103 (9.8) 4,936 
    1985-1988 4,601 (14.7) 361 (12.6) 123 (11.7) 5,085 
    1989-1992 4,696 (15.0) 448 (15.6) 202 (19.2) 5,346 
    1993-1996 5,043 (16.1) 469 (16.4) 186 (17.7) 5,698 
    1997-2000 5,529 (17.6) 515 (18.0) 249 (23.6) 6,293 
Gender     
    Male 16,299 (52.0) 1,420 (49.6) 581 (55.1) 18,300 
    Female 15,058 (48.0) 1,445 (50.4) 473 (44.9) 16,976 
Race     
    White 26,009 (83.5) 2,422 (85.2) 906 (86.4) 29,337 
    Black 3,521 (11.3) 283 (10.0) 93 (8.9) 3,897 
    Asian/Pacific Islander 1,622 (5.2) 137 (4.8) 50 (4.8) 1,809 
    Other/Unknown 205 23 233 
SEER registry     
    San Francisco 5,260 (16.8) 452 (15.8) 165 (15.7) 5,877 
    Connecticut 4,970 (15.9) 529 (18.5) 123 (11.7) 5,622 
    Detroit 6,490 (20.7) 498 (17.4) 181 (17.2) 7,169 
    Hawaii 1,435 (4.6) 103 (3.6) 50 (4.7) 1,588 
    Iowa 4,395 (14.0) 393 (13.7) 164 (15.6) 4,952 
    New Mexico 1,702 (5.4) 134 (4.7) 67 (6.4) 1,903 
    Seattle-Puget Sound 3,978 (12.7) 382 (13.3) 152 (14.4) 4,512 
    Utah 1,144 (3.7) 133 (4.6) 61 (5.8) 1,338 
    Atlanta 1,983 (6.3) 241 (8.4) 91 (8.6) 2,315 
SEER historic stage     
    Localized 2,760 (8.8) 239 (8.3) 121 (11.5) 3,120 
    Regional 8,911 (28.4) 645 (22.5) 245 (23.2) 9,801 
    Distant 19,686 (62.8) 1,981 (69.1) 688 (65.3) 22,355 
Surgery status     
    No cancer-directed surgery 16,083 (88.8) 1,382 (82.4) 565 (70.8) 18,030 
    Other cancer-directed surgery 135 (0.7) 38 (2.3) 57 (7.1) 230 
    Pancreatectomy 1,891 (10.4) 257 (15.3) 176 (22.1) 2,324 
    Unknown surgery 13,248 1,188 256 14,692 
Adenocarcinoma (n = 31,357)Mucinous tumors (n = 2,865)Endocrine tumors (n = 1,054)Total (n = 35,276)
Age at diagnosis n (%) n (%) n (%) n (%) 
    <50 2,472 (7.9) 261 (9.1) 317 (30.1) 3,050 
    50-59 5,776 (18.4) 514 (17.9) 240 (22.8) 6,530 
    60-69 10,027 (32.0) 972 (33.9) 266 (25.2) 11,265 
    70-79 9,514 (30.3) 840 (29.3) 187 (17.7) 10,541 
    80+ 3,568 (11.4) 278 (9.7) 44 (4.2) 3,890 
    Mean (SD) 67.3 (11.3) 66.7 (11.4) 58.0 (14.6) 67.0 (11.5) 
Year of diagnosis*     
    1973-1976 3,078 (9.8) 306 (10.7) 85 (8.0) 3,469 
    1977-1980 3,959 (12.6) 384 (13.4) 106 (10.0) 4,449 
    1981-1984 4,451 (14.2) 382 (13.3) 103 (9.8) 4,936 
    1985-1988 4,601 (14.7) 361 (12.6) 123 (11.7) 5,085 
    1989-1992 4,696 (15.0) 448 (15.6) 202 (19.2) 5,346 
    1993-1996 5,043 (16.1) 469 (16.4) 186 (17.7) 5,698 
    1997-2000 5,529 (17.6) 515 (18.0) 249 (23.6) 6,293 
Gender     
    Male 16,299 (52.0) 1,420 (49.6) 581 (55.1) 18,300 
    Female 15,058 (48.0) 1,445 (50.4) 473 (44.9) 16,976 
Race     
    White 26,009 (83.5) 2,422 (85.2) 906 (86.4) 29,337 
    Black 3,521 (11.3) 283 (10.0) 93 (8.9) 3,897 
    Asian/Pacific Islander 1,622 (5.2) 137 (4.8) 50 (4.8) 1,809 
    Other/Unknown 205 23 233 
SEER registry     
    San Francisco 5,260 (16.8) 452 (15.8) 165 (15.7) 5,877 
    Connecticut 4,970 (15.9) 529 (18.5) 123 (11.7) 5,622 
    Detroit 6,490 (20.7) 498 (17.4) 181 (17.2) 7,169 
    Hawaii 1,435 (4.6) 103 (3.6) 50 (4.7) 1,588 
    Iowa 4,395 (14.0) 393 (13.7) 164 (15.6) 4,952 
    New Mexico 1,702 (5.4) 134 (4.7) 67 (6.4) 1,903 
    Seattle-Puget Sound 3,978 (12.7) 382 (13.3) 152 (14.4) 4,512 
    Utah 1,144 (3.7) 133 (4.6) 61 (5.8) 1,338 
    Atlanta 1,983 (6.3) 241 (8.4) 91 (8.6) 2,315 
SEER historic stage     
    Localized 2,760 (8.8) 239 (8.3) 121 (11.5) 3,120 
    Regional 8,911 (28.4) 645 (22.5) 245 (23.2) 9,801 
    Distant 19,686 (62.8) 1,981 (69.1) 688 (65.3) 22,355 
Surgery status     
    No cancer-directed surgery 16,083 (88.8) 1,382 (82.4) 565 (70.8) 18,030 
    Other cancer-directed surgery 135 (0.7) 38 (2.3) 57 (7.1) 230 
    Pancreatectomy 1,891 (10.4) 257 (15.3) 176 (22.1) 2,324 
    Unknown surgery 13,248 1,188 256 14,692 
*

The Seattle-Puget Sound and Atlanta SEER registries did not contribute cases until January 1, 1974 and January 1, 1975, respectively.

Finally, surgery status was known for 58.3% of cases, although this proportion varied by histologic type as surgery status was known for 57.8% of the adenocarcinoma cases, 58.5% of the mucinous tumor cases, and 75.7% of the endocrine tumor cases (Table 1). The percentage of cases that received either a pancreatectomy or other cancer-directed surgery also differed by histologic type, ranging from 11.1% of adenocarcinoma cases to 17.6% of mucinous tumor cases and to 29.2% of endocrine tumor cases.

Survival and Mortality between Histologic Types

At all time points in the follow-up period, survival rates among endocrine pancreatic cancer cases were higher than for either adenocarcinoma or mucinous tumor cases (Fig. 1). For example, at 24 months, 51.6% of endocrine cases were alive compared with only 4.6% of adenocarcinoma cases and 8.6% of mucinous tumor cases. Median survival of endocrine pancreatic cancer cases was ∼2 years longer than for adenocarcinoma or the mucinous tumor cases (27 versus 4 months, respectively, Table 2). Compared with adenocarcinoma cases, patients with endocrine tumors and mucinous tumors had reduced adjusted risks of mortality (HR, 0.28; 95% CI, 0.26-0.30 and HR, 0.88; 95% CI, 0.84-0.91, respectively).

Figure 1.

Kaplan-Meier curves comparing percent survival for 5 years in the pancreatic cancer histologic types: adenocarcinoma (n = 31,357, solid line), mucinous tumors (n = 2,865, dotted line), and endocrine tumors (n = 1,054, dashed line).

Figure 1.

Kaplan-Meier curves comparing percent survival for 5 years in the pancreatic cancer histologic types: adenocarcinoma (n = 31,357, solid line), mucinous tumors (n = 2,865, dotted line), and endocrine tumors (n = 1,054, dashed line).

Close modal
Table 2.

Median survival times and adjusted HRs for mortality by histologic type of pancreatic cancer and gender

Histologic typen at riskPerson-years at riskNo. deathsMedian survival (mo)HR* (95% CI)
All pancreatic cancer cases      
    Adenocarcinoma 31,357 18,480 30,217 1.00 (reference) 
    Mucinous 2,865 2,276 2,658 0.88 (0.84-0.91) 
    Endocrine 1,054 3,542 759 27 0.28 (0.26-0.30) 
Men      
    Adenocarcinoma 16,299 9,229 15,726 1.0 (reference) 
    Mucinous 1,420 913 1,346 0.91 (0.86-0.97) 
    Endocrine 581 1,763 428 23 0.28 (0.26-0.31) 
Women      
    Adenocarcinoma 15,058 9,250 14,491 1.0 (reference) 
    Mucinous 1,445 1,363 1,312 0.84 (0.79-0.89) 
    Endocrine 473 1,779 331 37 0.27 (0.24-0.30) 
Histologic typen at riskPerson-years at riskNo. deathsMedian survival (mo)HR* (95% CI)
All pancreatic cancer cases      
    Adenocarcinoma 31,357 18,480 30,217 1.00 (reference) 
    Mucinous 2,865 2,276 2,658 0.88 (0.84-0.91) 
    Endocrine 1,054 3,542 759 27 0.28 (0.26-0.30) 
Men      
    Adenocarcinoma 16,299 9,229 15,726 1.0 (reference) 
    Mucinous 1,420 913 1,346 0.91 (0.86-0.97) 
    Endocrine 581 1,763 428 23 0.28 (0.26-0.31) 
Women      
    Adenocarcinoma 15,058 9,250 14,491 1.0 (reference) 
    Mucinous 1,445 1,363 1,312 0.84 (0.79-0.89) 
    Endocrine 473 1,779 331 37 0.27 (0.24-0.30) 
*

Hazard ratio defined as the instantaneous risk of death compared to the adenocarcinoma histologic type, adjusted for age at diagnosis, year of diagnosis, SEER registry, SEER historic stage, and race. Hazard ratios that include all cases are also adjusted for gender.

95% CI = 95% confidence interval.

P < 0.01.

Among mucinous tumor cases, the relative decrease in adjusted risk of mortality compared with adenocarcinoma cases was slightly greater among women (HR, 0.84; 95% CI, 0.79-0.89; Table 2) than among men (HR, 0.91; 95% CI, 0.86-0.97), although this difference was within the limits of chance. In endocrine tumor cases, the adjusted HRs were nearly identical in both genders (men: HR, 0.28; 95% CI, 0.26-0.31 and women: HR, 0.27; 95% CI, 0.24-0.30). However, women with endocrine tumors had a substantially longer median survival compared with men (37 versus 23 months).

Mortality within the Adenocarcinoma Cases

Table 3A presents median survival times and adjusted HRs for mortality among adenocarcinoma cases. Age at diagnosis, year of diagnosis, gender, race, tumor stage, and surgery were all related to risk of mortality in this group. Specifically, risk of mortality increased in each ascending category of age at diagnosis (Ptrend < 0.001), with corresponding decreases in median survival time. Patients diagnosed with adenocarcinoma in later calendar years had a decreased risk of mortality compared with cases diagnosed in the earliest time interval. This risk reduction increased in each time interval, culminating with a 27% reduction in risk of mortality in cases diagnosed in the 1997 to 2000 interval compared with those diagnosed between 1973 and 1976 (Ptrend < 0.001).

Table 3.

n at riskPerson-years at riskNo. deathsMedian survival (mo)HR* (95% CI)P-value for trend
A. Adjusted HRs for mortality by SEER historic stage, age at diagnosis, year of diagnosis, and surgery status among adenocarcinoma cases
 
      
Age at diagnosis (y)       
    <50 2,472 1,956 2,335 1.00 (reference) <0.001 
    50-60 5,776 4,089 5,521 1.11 (1.06-1.16)  
    60-70 10,027 6,315 9,678 1.23 (1.18-1.29)  
    70-80 9,514 4,881 9,211 1.50 (1.43-1.57)  
    >80 3,568 1,238 3,472 2.08 (1.97-2.20)  
Year of diagnosis       
    1973-1976 3,078 1,715 3,070 1.00 (reference) <0.001 
    1977-1980 3,959 2,171 3,954 0.92 (0.88-0.96)  
    1981-1984 4,451 2,759 4,431 0.90 (0.86-0.94)  
    1985-1988 4,601 2,804 4,569 0.89 (0.85-0.93)  
    1989-1992 4,696 3,082 4,643 0.82 (0.79-0.86)  
    1993-1996 5,043 3,199 4,943 0.80 (0.76-0.83)  
    1997-2000 5,529 2,749 4,607 0.73 (0.70-0.77)  
Gender       
    Male 16,299 9,229 15,726 1.00 (reference)  
    Female 15,058 9,250 14,491 0.92 (0.90-0.94)  
Race       
    White 26,009 15,333 25,114 1.00 (reference)  
    Black 3,521 1,951 3,399 1.11 (1.07-1.15)  
    Asian/Pacific Islander 1,622 1,094 1,515 0.94 (0.88-1.01)  
SEER historic stage       
    Localized 2,760 3,175 2,603 1.00 (reference) <0.001 
    Regional 8,911 8,051 8,369 1.17 (1.12-1.22)  
    Distant 19,686 7,253 19,245 2.43 (2.33-2.54)  
Surgery status       
    No cancer-directed surgery 16,083 9,138 15,340 1.00 (reference)  
    Pancreatectomy 1,891 2,809 1,537 13 0.53 (0.50-0.57)  
    Other cancer-directed surgery 135 152 121 0.70 (0.58-0.83)  
B. Adjusted HRs for mortality by SEER historic stage, age at diagnosis, year of diagnosis, and surgery status among mucinous cases       
Age at diagnosis (y)       
    <50 261 414 218 1.00 (reference) <0.001 
    50-60 514 461 474 1.20 (1.02-1.41)  
    60-70 972 700 910 1.37 (1.18-1.59)  
    70-80 840 604 786 1.65 (1.42-1.92)  
    >80 278 97 270 2.55 (2.12-3.07)  
Year of diagnosis       
    1973-1976 306 177 305 1.00 (reference) <0.001 
    1977-1980 384 228 383 1.01 (0.87-1.17)  
    1981-1984 382 224 378 0.98 (0.84-1.14)  
    1985-1988 361 328 352 0.92 (0.79-1.07)  
    1989-1992 448 568 418 0.85 (0.73-0.98)  
    1993-1996 469 437 436 0.86 (0.74-0.99)  
    1997-2000 515 314 386 0.68 (0.59-0.80)  
Gender       
    Male 1,420 913 1,346 1.00 (reference)  
    Female 1,445 1,363 1,312 0.87 (0.80-0.94)  
Race       
    White 2,422 1,896 2,261 1.00 (reference)  
    Black 283 171 269 1.33 (1.16-1.53)  
    Asian/Pacific Islander 137 185 108 0.86 (0.67-1.10)  
SEER historic stage       
    Localized 239 735 156 16 1.00 (reference) <0.001 
    Regional 645 769 575 2.00 (1.67-2.40)  
    Distant 1,981 772 1,927 4.64 (3.90-5.52)  
Surgery status       
    No cancer-directed surgery 1,382 893 1,305 1.00 (reference)  
    Pancreatectomy 257 655 151 24 0.39 (0.32-0.47)  
    Other cancer-directed surgery 38 192 17 § 0.30 (0.18-0.50)  
C. Adjusted HRs for mortality by SEER historic stage, age at diagnosis, year of diagnosis, and surgery status among endocrine tumor cases       
Age at diagnosis (y)       
    <50 317 1,532 190 51 1.00 (reference) <0.001 
    50-60 240 939 164 41 1.20 (0.97-1.49)  
    60-70 266 695 202 17 1.89 (1.54-2.31)  
    70-80 187 349 161 12 2.81 (2.25-3.49)  
    >80 44 27 42 5.79 (4.06-8.27)  
Year of diagnosis       
    1973-1976 85 402 80 11 1.00 (reference) <0.001 
    1977-1980 106 511 94 23 0.90 (0.66-1.23)  
    1981-1984 103 466 94 32 0.77 (0.57-1.06)  
    1985-1988 123 529 103 23 0.74 (0.55-1.00)  
    1989-1992 202 771 156 32 0.69 (0.52-0.91)  
    1993-1996 186 566 126 34 0.59 (0.44-0.79)  
    1997-2000 249 297 106 26 0.65 (0.47-0.88)  
Gender       
    Male 581 1,763 428 23 1.00 (reference)  
    Female 473 1,779 331 37 0.81 (0.70-0.94)  
Race       
    White 906 3,056 648 27 1.00 (reference)  
    Black 93 349 71 30 1.08 (0.83-1.41)  
    Asian/Pacific Islander 50 114 37 17 1.45 (0.93-2.25)  
SEER historic stage       
    Localized 121 686 55 99 1.00 (reference) <0.001 
    Regional 245 1,302 138 70 1.29 (0.94-1.78)  
    Distant 688 1,553 566 15 3.33 (2.50-4.45)  
Surgery status       
    No cancer-directed surgery 565 1,874 438 21 1.00 (reference)  
    Pancreatectomy 176 634 59 97 0.48 (0.36-0.65)  
    Other cancer-directed surgery 57 345 19 § 0.31 (0.19-0.51)  
n at riskPerson-years at riskNo. deathsMedian survival (mo)HR* (95% CI)P-value for trend
A. Adjusted HRs for mortality by SEER historic stage, age at diagnosis, year of diagnosis, and surgery status among adenocarcinoma cases
 
      
Age at diagnosis (y)       
    <50 2,472 1,956 2,335 1.00 (reference) <0.001 
    50-60 5,776 4,089 5,521 1.11 (1.06-1.16)  
    60-70 10,027 6,315 9,678 1.23 (1.18-1.29)  
    70-80 9,514 4,881 9,211 1.50 (1.43-1.57)  
    >80 3,568 1,238 3,472 2.08 (1.97-2.20)  
Year of diagnosis       
    1973-1976 3,078 1,715 3,070 1.00 (reference) <0.001 
    1977-1980 3,959 2,171 3,954 0.92 (0.88-0.96)  
    1981-1984 4,451 2,759 4,431 0.90 (0.86-0.94)  
    1985-1988 4,601 2,804 4,569 0.89 (0.85-0.93)  
    1989-1992 4,696 3,082 4,643 0.82 (0.79-0.86)  
    1993-1996 5,043 3,199 4,943 0.80 (0.76-0.83)  
    1997-2000 5,529 2,749 4,607 0.73 (0.70-0.77)  
Gender       
    Male 16,299 9,229 15,726 1.00 (reference)  
    Female 15,058 9,250 14,491 0.92 (0.90-0.94)  
Race       
    White 26,009 15,333 25,114 1.00 (reference)  
    Black 3,521 1,951 3,399 1.11 (1.07-1.15)  
    Asian/Pacific Islander 1,622 1,094 1,515 0.94 (0.88-1.01)  
SEER historic stage       
    Localized 2,760 3,175 2,603 1.00 (reference) <0.001 
    Regional 8,911 8,051 8,369 1.17 (1.12-1.22)  
    Distant 19,686 7,253 19,245 2.43 (2.33-2.54)  
Surgery status       
    No cancer-directed surgery 16,083 9,138 15,340 1.00 (reference)  
    Pancreatectomy 1,891 2,809 1,537 13 0.53 (0.50-0.57)  
    Other cancer-directed surgery 135 152 121 0.70 (0.58-0.83)  
B. Adjusted HRs for mortality by SEER historic stage, age at diagnosis, year of diagnosis, and surgery status among mucinous cases       
Age at diagnosis (y)       
    <50 261 414 218 1.00 (reference) <0.001 
    50-60 514 461 474 1.20 (1.02-1.41)  
    60-70 972 700 910 1.37 (1.18-1.59)  
    70-80 840 604 786 1.65 (1.42-1.92)  
    >80 278 97 270 2.55 (2.12-3.07)  
Year of diagnosis       
    1973-1976 306 177 305 1.00 (reference) <0.001 
    1977-1980 384 228 383 1.01 (0.87-1.17)  
    1981-1984 382 224 378 0.98 (0.84-1.14)  
    1985-1988 361 328 352 0.92 (0.79-1.07)  
    1989-1992 448 568 418 0.85 (0.73-0.98)  
    1993-1996 469 437 436 0.86 (0.74-0.99)  
    1997-2000 515 314 386 0.68 (0.59-0.80)  
Gender       
    Male 1,420 913 1,346 1.00 (reference)  
    Female 1,445 1,363 1,312 0.87 (0.80-0.94)  
Race       
    White 2,422 1,896 2,261 1.00 (reference)  
    Black 283 171 269 1.33 (1.16-1.53)  
    Asian/Pacific Islander 137 185 108 0.86 (0.67-1.10)  
SEER historic stage       
    Localized 239 735 156 16 1.00 (reference) <0.001 
    Regional 645 769 575 2.00 (1.67-2.40)  
    Distant 1,981 772 1,927 4.64 (3.90-5.52)  
Surgery status       
    No cancer-directed surgery 1,382 893 1,305 1.00 (reference)  
    Pancreatectomy 257 655 151 24 0.39 (0.32-0.47)  
    Other cancer-directed surgery 38 192 17 § 0.30 (0.18-0.50)  
C. Adjusted HRs for mortality by SEER historic stage, age at diagnosis, year of diagnosis, and surgery status among endocrine tumor cases       
Age at diagnosis (y)       
    <50 317 1,532 190 51 1.00 (reference) <0.001 
    50-60 240 939 164 41 1.20 (0.97-1.49)  
    60-70 266 695 202 17 1.89 (1.54-2.31)  
    70-80 187 349 161 12 2.81 (2.25-3.49)  
    >80 44 27 42 5.79 (4.06-8.27)  
Year of diagnosis       
    1973-1976 85 402 80 11 1.00 (reference) <0.001 
    1977-1980 106 511 94 23 0.90 (0.66-1.23)  
    1981-1984 103 466 94 32 0.77 (0.57-1.06)  
    1985-1988 123 529 103 23 0.74 (0.55-1.00)  
    1989-1992 202 771 156 32 0.69 (0.52-0.91)  
    1993-1996 186 566 126 34 0.59 (0.44-0.79)  
    1997-2000 249 297 106 26 0.65 (0.47-0.88)  
Gender       
    Male 581 1,763 428 23 1.00 (reference)  
    Female 473 1,779 331 37 0.81 (0.70-0.94)  
Race       
    White 906 3,056 648 27 1.00 (reference)  
    Black 93 349 71 30 1.08 (0.83-1.41)  
    Asian/Pacific Islander 50 114 37 17 1.45 (0.93-2.25)  
SEER historic stage       
    Localized 121 686 55 99 1.00 (reference) <0.001 
    Regional 245 1,302 138 70 1.29 (0.94-1.78)  
    Distant 688 1,553 566 15 3.33 (2.50-4.45)  
Surgery status       
    No cancer-directed surgery 565 1,874 438 21 1.00 (reference)  
    Pancreatectomy 176 634 59 97 0.48 (0.36-0.65)  
    Other cancer-directed surgery 57 345 19 § 0.31 (0.19-0.51)  
*

HRs for each risk factor are adjusted for all other factors in the table.

P < 0.001.

P < 0.05.

§

No median survival reported because >50% of all cases in the cell were alive by December 31, 2000.

The median survival times for men and women differed slightly (3 months for men and 4 months for women), and the adjusted reduction in risk associated with female gender was 8% in adenocarcinoma cases (P < 0.001). Compared with Whites, who had a median survival of 4 months, Blacks had a median survival of 3 months and an 1.11-fold (95% CI, 1.07-1.15) increased adjusted risk of mortality. Asian/Pacific Islanders were not different from Whites with respect to survival or risk of mortality. Compared with patients with localized adenocarcinoma, patients diagnosed with regional or distant adenocarcinoma had 1.17-fold (95% CI, 1.12-1.22) and 2.43-fold (95% CI, 2.33-2.54) increases in risk of mortality, respectively (Ptrend < 0.001).

Compared with adenocarcinoma cases who received no cancer-directed surgery, who had a median survival of 4 months, cases who received a partial or complete pancreatectomy had a median survival of 13 months (the longest median survival of any of the adenocarcinoma strata analyzed) and an 0.53-fold (95% CI, 0.50-0.57) reduced adjusted risk of mortality. Cases receiving other cancer-directed surgery also experienced improvements in survival time compared with cases receiving no surgery, with a median survival of 8 months and a 0.70-fold (95% CI, 0.58-0.83) decreased adjusted risk of mortality.

Mortality within Mucinous Tumor Cases

Table 3B presents median survival times and adjusted HRs for mortality among mucinous tumor cases. Similar to adenocarcinoma cases, age at diagnosis, year of diagnosis, gender, race, tumor stage, and surgery were all related to risk of mortality.

Cases with mucinous tumors diagnosed in all age groups after age 50 had increased risks of mortality compared with cases diagnosed before age 50 (Ptrend < 0.001). Cases diagnosed at age 80 or older had the greatest risk of mortality (HR, 2.55; 95% CI, 2.12-3.07). Risk of mortality decreased for cases in each ascending year of diagnosis, with the greatest reduction observed among cases diagnosed from 1997 to 2000, who had a 0.68-fold (95% CI, 0.59-0.80) reduction in risk of mortality compared with patients diagnosed from 1973 to 1976 (Ptrend < 0.001). The median survival times for men and women differed slightly for mucinous tumors (3 months for men and 4 months for women), and females in this group had a 0.87-fold (95% CI, 0.80-0.94) adjusted reduction in risk of mortality. Compared with Whites, who had a median survival of 4 months, Blacks had a shorter median survival of 3 months, and a 1.33-fold (95% CI, 1.16-1.53) increased adjusted risk of mortality. Asian or Pacific Islander cases had a slightly longer median survival of 6 months, but their adjusted reduction in risk of mortality was not different from that of Whites. The risk of mortality associated with stage increased in each higher stage and was greatest in cases with distant tumors, who had a 4.64-fold (95% CI, 3.90-5.52) increased risk of mortality compared with cases with localized tumors (Ptrend < 0.001).

Compared with cases who received no cancer-directed surgery, who had a median survival of 4 months, cases who received a partial or complete pancreatectomy had a median survival of 24 months and a 0.39-fold (95% CI, 0.32-0.47) reduced adjusted risk of mortality. Cases receiving other cancer-directed surgeries experienced similar improvements in survival time and risk of mortality compared with patients receiving no surgery.

Mortality within the Endocrine Tumor Cases

Table 3C presents median survival times and adjusted HRs for mortality among endocrine tumor cases. Age at diagnosis, year of diagnosis, gender, race, tumor stage, and surgery were again all related to risk of mortality in this group. The risk of death among cases with endocrine tumors increased with age (Ptrend < 0.001), culminating in a 5.79-fold (95% CI, 4.06-8.27) increased risk of mortality in patients diagnosed at age 80 or older compared with patients diagnosed before age 50.

Median survival durations and the magnitudes of the HRs tended to increase over time compared with cases diagnosed from 1973 to 1976 (Ptrend < 0.001). The median survival was more than a year longer among women with endocrine tumors compared with men with these tumors (37 versus 23 months, respectively), and females had a 0.81-fold (95% CI, 0.70-0.94) adjusted reduction in risk of mortality. Race was not associated with adjusted risk of mortality in endocrine tumor cases, although median survival differed somewhat by race. Distant endocrine tumors had a 3.33-fold (95% CI, 2.50-4.45) increased risk of mortality compared with localized tumors, but no increase in risk was found for regional tumors. However, median survival was 29 months shorter (70 versus 99 months) for regional tumors compared with localized tumors, and advanced tumor stage was associated with increased adjusted risk of mortality (Ptrend < 0.001).

Compared with subjects who received no cancer-directed surgery, who had a median survival of 21 months, cases who received a partial or complete pancreatectomy had a median survival of 97 months and a 0.48-fold (95% CI, 0.36-0.65) reduced adjusted risk of mortality. Patients receiving other cancer-directed surgery experienced even better survival and reductions in mortality: fewer than 50% of these cases died before the end of the study period and had a 0.31-fold (95% CI, 0.19-0.51) reduced adjusted risk of mortality compared with cases receiving no surgery.

The analyses presented here quantitatively show that survival time among pancreatic cancer cases varies by histologic type in a large, population-based setting. Specifically, patients diagnosed with cancer of the endocrine pancreas survive ∼2 years longer, on average, than those diagnosed with exocrine pancreatic cancer, including both adenocarcinoma and mucinous tumor cases. This result concurs with qualitative clinical observations of decreased mortality among endocrine pancreatic cancer cases compared with exocrine pancreatic cancer cases. After adjustment for age at diagnosis, gender, diagnosis year, stage, race, and SEER registry, there was a 0.28-fold decreased adjusted risk of mortality for endocrine tumors, and a 0.88-fold decreased adjusted risk of mortality for mucinous tumors compared with adenocarcinomas, although mucinous cases did not have a longer unadjusted median survival time. These decreased adjusted risks of mortality were similar among men and women, although the median survival time for women with endocrine cancer was considerably longer than it was for men (37 versus 23 months, respectively).

Whereas there are many published accounts of survival in specific patient subgroups (14-16, 23), we are not aware of any previous, population-based reports comparing survival between endocrine and exocrine pancreatic tumors. A previous analysis of data on 100,313 pancreatic cancer cases in the National Cancer Database estimated 5-year survival rates for different tumor stages and courses of treatment, but the National Cancer Database is not population-based, and that analysis did not examine survival within or between histologic types (24). Although differences in methodology preclude direct comparison between the National Cancer Database study and the results presented here, both studies found that surgery is associated with increased survival and documented that more advanced tumors are associated with decreased survival.

At this time, there is no known explanation for the difference in survival time between cases with exocrine and endocrine tumors, but tumors of the exocrine pancreas may be more lethal than endocrine tumors due to their cellular or molecular behavior. For example, pancreatic adenocarcinomas often block the pancreatic duct, resulting in jaundice and cachexia (25). In contrast, endocrine pancreatic tumors often overproduce normally occurring substances such as insulin and glucagons (13). How these histologic differences influence survival remains to be determined by basic science research studies.

Our observation that risks of mortality declined from 1973 to 2000 in each histologic type of pancreatic cancer suggests that some progress has been made in the diagnosis and/or treatment of the disease over this time period. For adenocarcinomas, this improvement has been modest, with only a slight increase in median survival time over the 28-year period (3 months in 1973-1976 versus 4 months in 1997-2000). The statistically significant decrease in risk of mortality over this same time period may be due to the large sample size in this analysis and may not represent a clinically significant improvement. A similar trend towards slight improvement in survival and risk of mortality over time was also seen in mucinous tumors. However, for endocrine tumors, increased survival times and reductions in risk of mortality over time have been more dramatic, as median survival times have improved from 11 months in 1973 to 1976 to 26 months in 1997 to 2000.

It is unclear why women with endocrine tumors survive >1 year longer than their male counterparts (37 versus 23 months). This finding suggests that hormonal factors may affect endocrine pancreatic cancer survival, as they are also related to the incidence of several other types of cancer(26, 27). In addition, several studies have found an association between hormones and reproductive factors and the incidence of exocrine pancreatic cancer. In the Nurse's Health Study, increased parity was significantly associated with a reduced risk of exocrine pancreatic cancer, with an average of 10% reduction in risk associated with each additional birth (28). In the Enhanced Cancer Surveillance project based in Canada, use of oral contraceptives was associated with a 0.36-fold (95% CI, 0.13-0.96) reduction in risk of exocrine pancreatic cancer (29). No epidemiologic study to date has investigated the role of hormonal factors in relation to endocrine pancreatic cancer risk, and no study has addressed the association between hormonal factors and pancreatic cancer survival. Furthermore, no prior studies have compared survival in men versus women diagnosed with different pancreatic cancer histologies. Thus, additional investigations aimed at furthering our understanding of the etiology of endocrine pancreatic tumors, especially differential risk by gender, are needed.

This analysis provides evidence of increased mortality risk among Blacks with exocrine pancreatic cancer compared with Whites. Previous analyses have not found consistent differences in pancreatic cancer mortality by race, including two studies using SEER data (30, 31). Unlike the results reported here, neither of these studies used SEER data from all nine registries in operation from 1973 to 2000. One of these studies found a higher incidence of pancreatic cancer in Blacks than Whites but reported no difference in risk of mortality (30). This is in contrast to our findings of a HR of 1.11 (95% CI, 1.07-1.15) and 1.33 (95% CI, 1.16-1.53) for Blacks compared with Whites with adenocarcinoma and mucinous tumors, respectively. The difference may be attributable to the fact that the previous study excluded all cases with unknown treatment, which constituted 41.6% of our sample. In a study using SEER centers with a large proportion of Asians, unadjusted median survival was longer in Asians than Whites, a finding that is not consistent with our results. This difference could be due to the inclusion of cases with unknown tumor stage in that study (11.1% of their sample; ref. 31), whereas we excluded such cases. Also in that study, median survival time in pancreatic cancer cases was slightly shorter among Black women than White women after adjustment for age, diagnosis year, tumor stage, tumor grade, and morphology, in agreement with our unadjusted median survival results. If the increased mortality risk for pancreatic cancer in Blacks is confirmed in future studies, there are at least two possible explanations to consider.

First, poorer health outcomes for Black versus White cancer cases have been reported in many types of cancer, including colorectal, breast, lung, and prostate cancers (32). Furthermore, a higher proportion of Black Americans than White Americans have no health insurance (33), and uninsurance or underinsurance has been associated with decreased survival time in several cancer types (34-36). These trends might also be expected to apply to pancreatic cancer cases. However, SEER does not collect data on social or economic variables; thus, it was not possible to investigate the interaction of socioeconomic risk factors with race on survival in this data set. In addition, prognostic biomarker profiles may vary between Whites and Blacks. Cases with K-ras mutations in the paraortic lymph nodes have shorter survival times than cases with lymph nodes free of K-ras mutations (37). Although the proportion of cases with K-ras mutations was similar in Whites and Blacks in one study (38), the prognostic value of specific K-ras and other mutations in Blacks and Whites warrant investigation as possible mechanisms influencing survival.

In this study, among partial or complete pancreatectomy or other cancer-directed surgery recipients, median survival was considerably greater than among cases receiving no cancer-directed surgery, no surgery, and with unknown surgery status in all histologic types. Previous research on pancreatic cancer survival has focused on cohorts of patients who have undergone pancreatic resection, rather than all diagnosed cases. For example, a recent study of pancreatic adenocarcinoma patients who underwent pancreatic resection reported a median survival of 13.6 months and a 5-year survival of 14.6% (14). In that study, treatment type, large tumor size, advanced stage, and high grade were each associated with decreased 5-year survival. This result is similar to our finding that tumors diagnosed at an advanced stage were associated with an increased risk of mortality and concurs with our report of a 13-month median survival in adenocarcinoma cases undergoing pancreatectomy.

The survival analyses conducted here, comparing cancer-directed surgery recipients with patients receiving no surgery, suggest that surgery increases survival time. However, surgery is generally offered to patients who have a better prognosis and less advanced disease. Thus, even if surgery conveyed no true survival benefit, the subgroup of patients who receive surgery are likely to live longer than those patients who were not surgical candidates. Adjustment for stage may not be sufficient to remove this bias, because prognosis can vary within each tumor stage. In addition, the proportion of patients who did not receive surgery varied between histologic types; thus, a direct comparison of surgery effects between histologic types is probably not valid. Whereas this analysis may overestimate the quantitative benefit of surgery, the large reduction in risk of mortality and increase in median survival in all histologic types suggests that surgery provides a survival benefit to pancreatic cancer patients.

Another implication of the results presented here is that the high case fatality rate of pancreatic cancer may introduce bias into population-based studies of cancer survivors, caused by a combination of recruitment of cases with less rapidly fatal pancreatic cancer types, and the unavailability of patients with more advanced disease. In particular, studies that recruit survivors of pancreatic cancer are likely to overrepresent cases with endocrine tumors and underrepresent cases with adenocarcinoma. Recent data analyses from the Cancer Genetics Network, a multisite national registry, illustrate this important bias (39). The Cancer Genetics Network uses SEER to identify cancer cases from six different cancer sites: melanoma, pancreatic, kidney, lung, thyroid, and non-Hodgkin's lymphoma, using identical recruitment and data collection methods for all cancer sites. Cancer Genetics Network researchers found that response rates (number of completed interviews over number of possibly eligible respondents) vary dramatically among the six cancer sites, from a low of 23% for pancreatic cancer to 51% for kidney cancer to 74% for bladder cancer. A major reason for this variation is the number of deceased cancer patients by the time of attempted contact. In contrast, completion rates (number of completed interviews divided by the number of eligible, contacted respondents) among patients from the six cancer sites varied much less, with a range of 78% to 96%. These results underscore the importance of rapid case recruitment strategies in pancreatic cancer research to better understand the underlying causes of all forms of pancreatic cancer. Conversely, it is important for physicians to realize that there are less fatal forms of pancreatic cancer that may benefit from surgery. For example, endocrine tumor cases who do not receive surgery have a median survival time of 21 months, but median survival time increases to 97 months among those cases who receive a pancreatectomy.

Whereas the population-based design of this study enhances the generalizability of its results, the noncentralized nature of SEER data collection at different geographic sites is a limitation of this study. Reviews of pathology reports and the recording of histology codes was conducted by a large number of SEER staff over 28 years at nine sites, using medical records and death certificates with varying levels of completeness and accuracy. In addition, histopathologic diagnoses were made by a large number of pathologists and physicians, with perhaps different methods of diagnosing pancreatic tumors and classifying their histology. Thus, there is likely to be some degree of misclassification not only by histologic type but also for the other variables collected by SEER that were used in this analysis. This data set is also limited by the small number of available potential confounding variables that could be related to survival following a pancreatic cancer diagnosis such as smoking status, alcohol use, comorbidities such as diabetes, access to health care, and socioeconomic status. Furthermore, it is important to note that excluding 14,455 cases with no known histology could bias the results, if survival time or underlying histologic type is related to missing data for the histology variable. It is possible that cases who die quickly may be more likely to have an unrecorded histologic type because they undergo fewer diagnostic procedures before dying. Thus, excluding these cases from the survival analyses may result in an overestimation of survival time for pancreatic cancer cases overall. However, if the distribution of underlying histologic types is similar both in cases with known and unknown histology, then the between-histologic type comparisons are valid.

In summary, this large, population-based, quantitative analysis confirms the clinical observation of increased median survival time in endocrine pancreatic cancer compared with either pancreatic adenocarcinoma or mucinous pancreatic tumors (27 versus 4 months, respectively). Furthermore, a larger percentage of endocrine than exocrine cases survived at all time points up to 5 years after diagnosis. Among patients with endocrine tumors, women survived substantially longer than men (37 versus 23 months, respectively). Within histologic types, advanced tumor stage, older diagnosis age, surgery, and Black race were associated with increased risk of mortality, whereas female sex and more recent year of diagnosis were associated with decreased risk. Although selection bias may be present, the results also suggest that surgery provides survival benefit. Better understanding of these differences in survival could contribute to identifying the underlying causes of pancreatic cancer and increasing survival among all histologic types.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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