Background:

Cancer survivors are developing more subsequent tumors. We sought to characterize patients with multiple (≥2) primary cancers (MPC) to assess associations and genetic mechanisms.

Methods:

Patients were prospectively consented (01/2013–02/2019) to tumor-normal sequencing via a custom targeted panel (MSK-IMPACT). A subset consented to return of results of ≥76 cancer predisposition genes. International Agency for Research on Cancer (IARC) 2004 rules for defining MPC were applied. Tumor pairs were created to assess relationships between cancers. Age-adjusted, sex-specific, standardized incidence ratios (SIR) for first to second cancer event combinations were calculated using SEER rates, adjusting for confounders and time of ascertainment. Associations were made with germline and somatic variants.

Results:

Of 24,241 patients, 4,340 had MPC (18%); 20% were synchronous. Most (80%) had two primaries; however, 4% had ≥4 cancers. SIR analysis found lymphoma–lung, lymphoma–uterine, breast–brain, and melanoma–lung pairs in women and prostate–mesothelioma, prostate–sarcoma, melanoma–stomach, and prostate–brain pairs in men in excess of expected after accounting for synchronous tumors, known inherited cancer syndromes, and environmental exposures. Of 1,580 (36%) patients who received germline results, 324 (21%) had 361 pathogenic/likely pathogenic variants (PV), 159 (44%) in high penetrance genes. Of tumor samples analyzed, 55% exhibited loss of heterozygosity at the germline variant. In those with negative germline findings, melanoma, prostate, and breast cancers were common.

Conclusions:

We identified tumor pairs without known predisposing mutations that merit confirmation and will require novel strategies to elucidate genetic mechanisms of shared susceptibilities.

Impact:

If verified, patients with MPC with novel phenotypes may benefit from targeted cancer surveillance.

This article is featured in Highlights of This Issue, p. 303

A substantial proportion of cancers (18%) occur in patients who have already had prior malignancies, and 10% to 25% of patients with cancer subsequently develop multiple primary cancers (MPC; refs. 1, 2). Occurrence of MPC is increasing as treatments improve and cancer becomes more common in elderly patients (1, 3). Rates of MPC vary across tumor types and reflect environmental exposures, including smoking, alcohol, obesity, and prior cancer treatments, and underlying genetic factors, including known inherited, cancer syndromes (4).

Although emphasis has been placed on public health efforts to reduce risk of subsequent cancers (5), treatment related or exogenous exposures do not fully explain the risk for MPCs (6), and both known and unknown underlying genetic factors contribute to cancer risk. As concurrent sequencing of tumor and germline DNA (parallel sequencing; ref. 7) is becoming more common in cancer care, there are opportunities to study the inherited and somatic genetics underlying MPCs to define novel susceptibilities associated with specific tumor combinations (2, 8).

We sought to comprehensively characterize the clinical and genetic features of patients with MPCs who underwent massively parallel sequencing. We utilized epidemiologic methodologies to define significant co-incidence patterns of MPC and analyzed these findings with germline and somatic DNA sequencing for known cancer predisposition genes. In addition to informing clinical and preventive management, this approach sets the stage for deeper sequencing and computational approaches to facilitate gene discovery.

Patient selection

Participants were identified from an institutional database (MSK-IMPACT) of patients who gave written informed consent to undergo parallel sequencing via custom, targeted panel as part of an Institutional Review Board approved study (NCT01775072; refs. 9, 10). Of the 24,241 patients consented prospectively from January 2013 to February 2019, 4,696 patients with ≥2 cancers and at least one tumor (any order) sequenced were identified through database query. Subsequently, International Agency for Research on Cancer (IARC) rules (11) for MPC were applied to define separate primaries. Briefly, IARC rules state that a primary tumor is one that originates in a primary site or tissue and is not an extension, recurrence, or metastasis. The existence of MPC does not depend on time. Only one tumor shall be recognized as arising in an organ or a pair of organs with the following exceptions: (i) systemic cancers involving multiple different organs and (ii) neoplasms of different morphology.

Subsequently, 356 patients were excluded, resulting in 4,340 patients with multiple (≥2) primary cancers and tumor sequencing of at least one tumor, with 764 (17.6%) having undergone tumor sequencing of >1 sample. These 4,340 patients with MPC were included in the epidemiologic analysis, where clinical characteristics were represented by summary statistics, and tumor types were tabulated for each individual patient and counted separately (pooled analysis). For the subset of 1,580 patients consenting to receipt of germline analysis of ≥76 cancer predisposition genes, it was permitted to link clinicopathologic characteristics and germline pathogenic/likely pathogenic variants (PV) on individual identified samples (Fig. 1). All analyses were conducted in accordance with recognized ethical guidelines under MSK IRB 12-245 and 18-420.

Figure 1.

Overview of patient selection and number of primary tumors. A, The identification of 4,340 patients with MPC using IARC criteria from a cohort of 24,241 patients who consented to tumor-normal sequencing. A subset of 1,580 patients consented to receive germline results, with 324 having 361 PV. B, The number of primary cancers per patient in those with MPC. C, The epidemiologic analysis of pooled tumors and all tumor pairs from patients with MPC.

Figure 1.

Overview of patient selection and number of primary tumors. A, The identification of 4,340 patients with MPC using IARC criteria from a cohort of 24,241 patients who consented to tumor-normal sequencing. A subset of 1,580 patients consented to receive germline results, with 324 having 361 PV. B, The number of primary cancers per patient in those with MPC. C, The epidemiologic analysis of pooled tumors and all tumor pairs from patients with MPC.

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Data collection/analysis

Patient sex, age at first cancer diagnosis, self-reported race/ethnicity, and Ashkenazi Jewish (AJ) ancestry (self-reported or documented in the medical record) were abstracted from the medical record and clinical databases. Smoking status was defined as ever versus never smoker. Body mass index (BMI) was obtained from the time of tumor sequencing. Data regarding cancer diagnoses, both before and after enrollment onto MSK-IMPACT, were collected from the institution's Cancer Database (CDB) which comprehensively collects data via review of ICD codes, pathology reports, and medical records to encompass self-reported cancer diagnoses, regardless of where treatment occurred. IARC rules (11) were used to evaluate tumor type from ICD codes, histology codes, and laterality to define MPC as summarized above. Tumor types were then grouped per Oncotree (12) categories to facilitate analysis. Cases with conflicting or ambiguous diagnoses were manually reviewed by medical oncologists (YLL and KC).

Distribution and relationship of cancer types

To assess distribution and relationship of different types of cancers, tumor pairs were constructed and plotted on the basis of frequency, regardless of time of occurrence (Supplementary Fig. S1). Figures and heatmaps of tumor pairs were created and stratified by sex, age at diagnosis (<50 and 50+; ref. 13), number of MPCs (2 vs. 3+), consent for receipt of germline findings (yes vs. no), and germline findings (positive vs. negative for PV). Tumor pairs were also depicted for those with synchronous primaries, defined as 1st and 2nd cancers with same age of diagnosis.

Standardized incidence ratios (SIR)

Age- and sex-specific incidence rates for 35 cancer types were obtained from the SEER-21 database as reference. For this analysis, cancer types in our cohort were grouped according to SEER groupings, and those without corresponding SEER data were excluded from this analysis. For a tumor pair, the probability that the patient develops the second tumor, for a given first primary tumor, was calculated using the age-adjusted SEER rates for the time from onset of first cancer to either the second cancer for MPC or last follow-up for single primary cancers (SPC) from our institutional database (MSK-IMPACT; Supplementary Materials and Methods). The expected count for the tumor pair is the sum of all these probabilities, and the SIR is estimated as the ratio of observed to expected count. The confidence bounds for the SIR were calculated using percentile bootstrap intervals by resampling the subjects and repeating the SIR calculations (14). Given observed differences in distribution of date of diagnosis for first primary cancer compared with second primary cancer or patients with SPC, a weight function was used to downweigh the MPC cases whose first primaries were diagnosed farther in the past. Different weighting levels were explored in a sensitivity analysis. This analysis was performed overall and then repeated excluding cancers diagnosed within 1 year to control for synchronous primaries. Analyses were restricted to SIRs with weighted expected frequency ≥1 and weighted number of pairs ≥2 to exclude outliers, and sensitivity analysis was performed for additional pairs with expected frequency ≥0.5. SIR analysis was not performed for likelihood of developing third or later cancers due to limited sample size. Groupings associated with known exposures or hereditary cancer syndrome were annotated (6, 15, 16), and scoring of known inherited cancer syndromes was performed as described in Supplementary Table S1.

Germline analysis

Blood and tumor samples were analyzed using a custom panel (MSK-IMPACT), and germline variant calling was performed as described previously (10, 17). Identified variants were independently assessed and manually curated, applying current standards for variant classification by the American College of Medical Genetics and Genomics (18), to define likely pathogenic/pathogenic variants, here referred to as PV. Germline variants from the .bam files of the nontumor DNA sequence with mapping and base quality scores of >20 were called using MuTect (19) and GATK Haplotypecaller (20) using 25% variant frequency and 20× coverage thresholds. All variants with <1% population frequency in the Exome Aggregation Consortium (ExAC) database were interpreted. Copy-number variations were assessed using an in-house developed pipeline and were confirmed with an additional laboratory tests (21). Variants of uncertain significance were reviewed but not reported in this analysis. PV (mutations) were classified as high [relative risk (RR), >4], intermediate (RR, 2–4) or low (RR, <2) penetrance, recessive, or of uncertain clinical actionability based on disease risks and prior modeling (17, 22, 23). Genes of uncertain clinical actionability included MRE11A, RAD50, TERT, RECQL, ERCC3, RAD51B, PAX5, and the CHEK2 I157T. Genotype–phenotype associations were assessed, and concordance was defined as having at least one tumor type known to be associated with the PV per our genetics clinical guidelines.

Loss of heterozygosity (LOH) analysis

LOH was assessed using the FACETS algorithm (24), which was performed on tumor samples from patients in whom a pathogenic germline variant was identified (n = 324). As some patients had multiple tumor samples tested (n = 359 tumor samples), and 38 samples from 34 unique patients had two germline PV identified, there were a total of n = 397 instances where a germline PV was assessed for LOH in each tumor sample. Of these, output data from FACETS was available for 381, with the algorithm having failed for 16 samples where LOH was unable to be determined due to lack of coverage at the specific loci (n = 11), low tumor burden (n = 2), genome fragmentation at the loci (n = 2), and unknown reason (n = 1). The proportion of tumors exhibiting LOH was quantified for the entire cohort and then stratified by gene penetrance (high vs. not high) and concordant/discordant tumor type. Given variability in tumor purity, sensitivity analysis was performed at different purity levels.

Data availability

A subset of the human sequencing data (MSK-IMPACT) utilized in this study are available via cbioportal.org. The full SIR dataset generated in this study is not publicly available due to ongoing research projects but are available upon request from the corresponding author. Other data generated in this study are available within the article and its supplementary data files.

Patient characteristics

Of the 24,241 patients undergoing tumor sequencing, 4,340 (18%) patients had multiple primary tumors. Of these, 2,424 (56%) were female. Median age of first cancer diagnosis was 58 (range 0–89), and 100 patients (2%) had their initial cancer diagnosis before adulthood (<18 years of age). The majority (n = 3,697, 85%) were Non-Hispanic White, and 919 (21%) were of AJ ancestry. Among those with MPC, 2,230 (51%) patients described themselves as ever smokers. Median BMI at time of tumor sequencing was 27 (range 16–47) in men and 25 (range 15–54) in women. Most patients (n = 3,465, 80%) had two primary tumors; however, 683 (16%) had three, 141 (3%) had four, and 51 (1%) had ≥5 primary tumors, Table 1 and Fig. 1. Synchronous primaries were found in 877 (20%) of patients with MPCs. The most common synchronous cancers were breast–breast (n = 170), lung–lung (N = 101), bladder–prostate (N = 48), uterus–ovary (N = 31), and melanoma–melanoma (N = 26; Supplementary Fig. S2).

Table 1.

Patient demographics, overall, and stratified by those who consented to germline testing and with PV.

N = 4,340 OverallN = 2,760 (No germline testing)N = 1,580 (Germline testing)P valueaN = 1,256 (No germline PV)N = 324 (Germline PV)P valuea
Male 1,916 (44%) 1,220 (44%) 696 (44%) 0.92 561 (45%) 135 (42%) 0.33 
Female 2,424 (56%) 1,540 (56%) 884 (56%)  695 (55%) 189 (58%)  
Race 
 White 3,697 (85%) 2,362 (86%) 1,335 (84%) 0.111 1,062 (85%) 273 (85%) 0.188 
 Black 234 (6%) 131 (5%) 103 (7%)  89 (7%) 14 (4%)  
 Asian 194 (4%) 125 (4%) 69 (4%)  52 (4%) 17 (5%)  
 Other 65 (2%) 46 (2%) 19 (1%)  13 (1%) 6 (2%)  
 Unknown 150 (3%) 96 (3%) 54 (3%)  40 (3%) 14 (4%)  
Ethnicity 
 Hispanic 150 (3%) 84 (3%) 66 (4%) 0.052 46 (4%) 20 (6%) 0.121 
 Not Hispanic 4,110 (95%) 2,631 (95%) 1,479 (94%)  1,183 (94%) 296 (91%)  
 Unknown 80 (2%) 45 (2%) 35 (2%)  27 (2%) 8 (3%)  
Ashkenazi Jewish 
 Yes 919 (21%) 554 (20%) 365 (23%) 0.019 280 (22%) 85 (26%) 0.133 
 No 3,421 (79%) 2,206 (80%) 1,215 (77%)  976 (78%) 239 (74%)  
Median age at first diagnosis (range) 58 (0–89) 58 (0–89) 56 (0–88) <0.001 57 (0–88) 51 (0–86) <0.001 
<18 years 100 (2%) 56 (2%) 44 (3%)  30 (2%) 14 (4%)  
Ever smoker 2,230 (51%) 1,535 (56%) 695 (44%) <0.001 556 (44%) 139 (43%) 0.66 
Median BMI at sequencing (range) 
 Male 27 (16–47) 27 (21–42) 27 (16–47) 0.74 27 (16–47) 27 (18–37) 0.83 
 Female 25 (15–54) 25 (18–32) 25 (15–54) 0.47 26 (15–54) 23 (17–48) 0.14 
Number of primary cancers 
 2 3,465 (80%) 2,209 (80%) 1,256 (79%) 0.92 1,015 (81%) 241 (74%) 0.004 
 3 683 (16%) 429 (15%) 254 (16%)  191 (15%) 63 (19%) (0.014, 
 4 141 (3%) 88 (3%) 53 (3%)  34 (3%) 19 (6%) 2 vs. 3+ primaries) 
 ≥5 51 (1%) 34 (1%) 17 (1%)  16 (1%)  
        
N = 4,340 OverallN = 2,760 (No germline testing)N = 1,580 (Germline testing)P valueaN = 1,256 (No germline PV)N = 324 (Germline PV)P valuea
Male 1,916 (44%) 1,220 (44%) 696 (44%) 0.92 561 (45%) 135 (42%) 0.33 
Female 2,424 (56%) 1,540 (56%) 884 (56%)  695 (55%) 189 (58%)  
Race 
 White 3,697 (85%) 2,362 (86%) 1,335 (84%) 0.111 1,062 (85%) 273 (85%) 0.188 
 Black 234 (6%) 131 (5%) 103 (7%)  89 (7%) 14 (4%)  
 Asian 194 (4%) 125 (4%) 69 (4%)  52 (4%) 17 (5%)  
 Other 65 (2%) 46 (2%) 19 (1%)  13 (1%) 6 (2%)  
 Unknown 150 (3%) 96 (3%) 54 (3%)  40 (3%) 14 (4%)  
Ethnicity 
 Hispanic 150 (3%) 84 (3%) 66 (4%) 0.052 46 (4%) 20 (6%) 0.121 
 Not Hispanic 4,110 (95%) 2,631 (95%) 1,479 (94%)  1,183 (94%) 296 (91%)  
 Unknown 80 (2%) 45 (2%) 35 (2%)  27 (2%) 8 (3%)  
Ashkenazi Jewish 
 Yes 919 (21%) 554 (20%) 365 (23%) 0.019 280 (22%) 85 (26%) 0.133 
 No 3,421 (79%) 2,206 (80%) 1,215 (77%)  976 (78%) 239 (74%)  
Median age at first diagnosis (range) 58 (0–89) 58 (0–89) 56 (0–88) <0.001 57 (0–88) 51 (0–86) <0.001 
<18 years 100 (2%) 56 (2%) 44 (3%)  30 (2%) 14 (4%)  
Ever smoker 2,230 (51%) 1,535 (56%) 695 (44%) <0.001 556 (44%) 139 (43%) 0.66 
Median BMI at sequencing (range) 
 Male 27 (16–47) 27 (21–42) 27 (16–47) 0.74 27 (16–47) 27 (18–37) 0.83 
 Female 25 (15–54) 25 (18–32) 25 (15–54) 0.47 26 (15–54) 23 (17–48) 0.14 
Number of primary cancers 
 2 3,465 (80%) 2,209 (80%) 1,256 (79%) 0.92 1,015 (81%) 241 (74%) 0.004 
 3 683 (16%) 429 (15%) 254 (16%)  191 (15%) 63 (19%) (0.014, 
 4 141 (3%) 88 (3%) 53 (3%)  34 (3%) 19 (6%) 2 vs. 3+ primaries) 
 ≥5 51 (1%) 34 (1%) 17 (1%)  16 (1%)  
        

aP values represent rank sum for continuous variables and chi-squared or Fisher exact for categorical variables.

Pooled analysis

Of the 9,812 total primary tumors observed among patients with MPC, the most common tumor types were breast (N = 1960, 20%), lung (N = 1387, 14.1%), prostate (N = 856, 8.7%), melanoma (N = 773, 7.9%), and bladder cancer (N = 454, 4.6%). In men, the most common tumor types were prostate (N = 856, 19.8%), lung (N = 552, 12.8%), and melanoma (N = 451, 10.5%), whereas, in women, the most common tumor types were breast (N = 1,926, 35.1%), lung (N = 827, 15.1%), and uterus/endometrial (N = 357, 6.5%; Supplementary Table S2). In those with 5+ primary tumors, the most common tumor types were melanoma (N = 79), lung (N = 38), breast (N = 30), colon (N = 16), and prostate (N = 13) cancers (Supplementary Table S3).

Tumor pairs

Of 3,921 tumor pairs in women, the most common were breast–breast (n = 593, 15%), breast–lung (n = 330, 8%), and lung–lung (n = 230, 6%; Fig. 2A). Of 3,021 tumor pairs in men, the most common were bladder–prostate (n = 199, 7%), melanoma–melanoma (n = 172, 6%), and prostate–lung (n = 168, 6%; Fig. 2B). In those <50 years old, breast–cancer pairs were observed frequently, whereas prostate and lung cancer pairs were observed frequently in those age 50+ (Fig. 3A). Ovarian and pancreatic cancers were observed frequently in those with two primaries. Lung and melanoma pairs were observed frequently in those with 3+ primaries. Breast cancers were common in both groups (Fig. 3B). To assess for bias in those consented to receipt of germline findings compared with those not consented, we compared tumor pairs in each group and found that lung cancers and melanoma were overrepresented in the group not consented to germline results (Fig. 3C). In those with positive germline findings, breast–breast, breast—ovary, and breast–pancreas pairs were common. Melanoma, thyroid, prostate, and lung pairs were common in those without germline findings (Fig. 3D).

Figure 2.

Heat maps of all tumor pairs in females and males. These heat maps depict the most common tumor pairs created from all tumor combinations and the number of pairs observed for females (A) and males (B). The darker colors represent more frequently observed pairs.

Figure 2.

Heat maps of all tumor pairs in females and males. These heat maps depict the most common tumor pairs created from all tumor combinations and the number of pairs observed for females (A) and males (B). The darker colors represent more frequently observed pairs.

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Figure 3.

Tumor pairs stratified by age, number of primary tumors, germline consent, and germline findings (PV vs. no PV). Top tumor pairs are plotted as a percentage (x-axis) out of total tumor pairs per group (N), stratified by age at first cancer diagnosis (<50 vs. 50+; A), number of primaries (2 vs. 3+; B), consent for germline results; C), and germline findings (PV vs. no PV; D).

Figure 3.

Tumor pairs stratified by age, number of primary tumors, germline consent, and germline findings (PV vs. no PV). Top tumor pairs are plotted as a percentage (x-axis) out of total tumor pairs per group (N), stratified by age at first cancer diagnosis (<50 vs. 50+; A), number of primaries (2 vs. 3+; B), consent for germline results; C), and germline findings (PV vs. no PV; D).

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SIRs: comparison with SEER

Weighted (w = 0.9), sequential 1st–2nd metachronous tumor pair combinations (synchronous removed) seen in excess of expected SIR included lymphoma–lung, lymphoma–uterus, breast–sarcoma, and breast–brain in women and melanoma–melanoma, melanoma–pancreas, prostate–mesothelioma, prostate–sarcoma, and kidney–kidney in men (Fig. 4; Supplementary Table S4). Synchronous primaries (yellow) included uterus–ovary, lung–lung, rectum–lung, and colon–colon in women and kidney–kidney, colon–rectum, colon–colon, and bladder–prostate in men (Supplementary Table S4). In this analysis, metachronous combinations were scored as associated with known hereditary cancer syndromes (blue) or possible exposures such as smoking (green) and obesity (black). Subsequently, combinations not thought to be related to a known hereditary cancer syndrome or environmental exposure were identified and included lymphoma–lung, lymphoma–uterus, breast–brain, and melanoma–lung in women and prostate–mesothelioma, prostate–sarcoma, melanoma–stomach, prostate–brain, and lymphoma–lung in men (Supplementary Table S4). Many of these associations remained significant using different weighting factors (Supplementary Table S5). Relaxing thresholds for expected frequency (≥0.5) revealed additional associations including melanoma–melanoma, breast–gallbladder, and lymphoma–thyroid in women and prostate–gallbladder, melanoma–brain, and lymphoma–pancreas in men (Supplementary Table S5).

Figure 4.

Weighted (w = 0.9), age-adjusted SIRs for 1st–2nd primary cancers stratified by sex for metachronous tumor pairs. This figure depicts weighted (w = 0.9), age-adjusted SIRs, and 95% CIs for metachronous 1st–2nd primary cancer pairs significantly observed in excess of expected, stratified by sex (female and male; A and B).

Figure 4.

Weighted (w = 0.9), age-adjusted SIRs for 1st–2nd primary cancers stratified by sex for metachronous tumor pairs. This figure depicts weighted (w = 0.9), age-adjusted SIRs, and 95% CIs for metachronous 1st–2nd primary cancer pairs significantly observed in excess of expected, stratified by sex (female and male; A and B).

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Germline analysis

Of the 4,340 patients, germline genetic testing data were available in 1,580 patients, of which 324 (21%) patients had at least one germline PV identified. Rates of germline PV were similar in those with synchronous versus metachronous cancers (19% vs. 21%, P = 0.54). Those with PV were younger at first cancer diagnosis (P < 0.001) and more likely to have >2 primary cancers (P = 0.004). Those consenting to return of germline results (n = 1,580) were less likely to have ever smoked compared with those not consenting to receipt of germline results (n = 2,760; P < 0.001). Although there was a higher proportion of AJ patients consented to receipt of germline results compared with those not consented (23% vs. 20%, P = 0.019), the proportion of those with positive results on germline testing was similar between AJ and non-AJ patients (26% vs. 22%, P = 0.133; Table 1).

We identified 361 PVs, with 33 patients having two, and 2 patients having three variants. Of these, 158 (44%) were in high penetrance genes (e.g., BRCA1/2, mismatch repair genes, and TP53), 73 (20%) in moderate penetrance genes (e.g., CHEK2 and ATM), and the remainder 130 (36%) were in low penetrance genes or genes of uncertain clinical utility (Fig. 5). Among all PV, 104 (29%) were founder mutations, of which 78 (75%) were AJ founder mutations. There was a higher prevalence of high (60% vs. 44%) and moderate (24% vs. 19%) penetrance genes and a lower prevalence of low/recessive and uncertain (16% vs. 37%) penetrance genes in those with three or more primary tumors compared with those with two primary tumors, P = 0.002.

Figure 5.

Depicts analysis of genotype–phenotype associations in the 324 patients who consented to receive germline results with PV. A, Distribution of PVs by gene penetrance. B, Proportion of patients with phenotypic concordance (at least one tumor type associated with syndromic phenotype typically represented by the germline variant) and discordance (no observed tumor type associated with the syndromic phenotype characteristic of the germline variant) by gene penetrance. C, Levels of LOH at the specific PV in tumor samples by gene penetrance. D, Genotype–phenotype concordance for select genes. E, LOH in tumor samples for concordant versus discordant cancer types for high and moderate penetrance variant.

Figure 5.

Depicts analysis of genotype–phenotype associations in the 324 patients who consented to receive germline results with PV. A, Distribution of PVs by gene penetrance. B, Proportion of patients with phenotypic concordance (at least one tumor type associated with syndromic phenotype typically represented by the germline variant) and discordance (no observed tumor type associated with the syndromic phenotype characteristic of the germline variant) by gene penetrance. C, Levels of LOH at the specific PV in tumor samples by gene penetrance. D, Genotype–phenotype concordance for select genes. E, LOH in tumor samples for concordant versus discordant cancer types for high and moderate penetrance variant.

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The distribution of tumor types in those with an identified germline PV were consistent with known associations, and there was high genotype–phenotype concordance overall (68%). We observed a higher genotype–phenotype concordance in high (89%) compared with moderate (58%) and low (15%) penetrance genes (58%), P < 0.001 (Fig. 5; Supplementary Table S6). The most frequently observed high penetrance genes were BRCA1/2, MLH1/MSH2, and TP53, which all exhibited high canonical genotype–phenotype concordance. The most frequently observed moderate penetrance genes were CHEK2 and ATM, which exhibited lower levels of genotype–phenotype concordance (Fig. 5; Supplementary Table S6).

Loss of heterozygosity

Of the 381 tumors profiled in 324 patients with at least one pathogenic germline variant, 174 (46%) exhibited LOH. LOH was significantly higher for high (62%) compared with moderate (44%) and low (29%) penetrance genes, P < 0.01 overall and for comparisons of high versus moderate and high versus low penetrance genes (Fig. 5). LOH rates were similar when analyzing PV groups with varying tumor purity cutoffs (Supplementary Table S7). LOH was observed in 64% of concordant and 55% of discordant tumors in high penetrance cases and 45% of concordant and 37% of discordant tumors in moderate penetrance cases (Fig. 5).

In this study of 24,241 patients with cancer undergoing parallel tumor-normal sequencing, 18% had MPCs. Novel tumor pairs not attributed to known inherited cancer syndromes or exposures were identified including lymphoma–lung, lymphoma–uterus, breast–brain, and melanoma–lung in women and prostate–mesothelioma, prostate–sarcoma, melanoma–stomach, prostate–brain, and lymphoma–lung in men. Among patients with MPC who consented to germline genetic testing, 21% had at least one PV identified, of which 44% were in high penetrance genes. LOH in tumors was observed for 46% of tumor variants, and this rate was higher (62%) for high penetrance genes as compared with moderate/low penetrance genes (33%).

The MPC rate of 18% reported here is consistent with prior studies and SEER data showing rates ranging from 2% to 25% (1, 2, 25). Older (1992–2008) SEER database studies derived the incidence of second primary cancers to be 8.1% (25). However, recent reports show that MPC rates are increasing over time, particularly in the elderly population (age ≥ 65; refs. 2, 3). An updated analysis of the SEER database (2009–2013) found an MPC rate of 18.4% and observed that this rate was higher for those age 65 and older (1). The median age of diagnosis for initial cancer for our cohort was younger, and only 1046 (24%) of patients were ≥65 years at initial cancer diagnosis. For this analysis, we used the IARC classification for MPC as it is more stringent and leads to lower MPC rates than the SEER definition (26).

Prior population-based studies utilizing cancer registry data have characterized the epidemiology of MPCs and primarily identified an excess of cancers associated with exposures such as smoking and alcohol, for example, lung, bladder, esophageal, and head/neck (1, 25–27). A SEER analysis (1992–2011) of >1.5 million cancer survivors found that 156,444 subsequently developed MPCs, with most cancers associated with environmental exposures (6). Those reports highlighted the need for preventive strategies; however, those studies were limited by lower-than expected rates of common cancers such as prostate and breast cancer and lack of germline analysis. In contrast, this study did not observe an excess of exposure-related 1st–2nd cancer pairs compared with prior population-based studies (6, 25), potentially reflecting the different tumor composition of this population referred to a comprehensive cancer center compared to registry-based analyses.

Even after removing pairs presumably associated with known inherited cancer syndromes or exposures, significant associations of tumor pairs involving melanoma, lymphoma, uterine, breast, prostate, lung, sarcoma, and thyroid cancers were observed. Of the novel tumor pairs, the statistical association of lung cancer following lymphoma was shown in a prior meta-analysis, and treatments such as radiotherapy (RT), particularly in Hodgkin's lymphoma, were hypothesized to influence this association (28). Notably, 7 of 20 (35%) women and 7 of 19 (37%) men with lung cancer after lymphoma received RT in our cohort, and other cancers after lymphoma (e.g., breast cancer) may also be related to radiation, a finding that should be explored in future studies with more comprehensive assessments of prior therapies. Some cancers may be incidentally detected during workup of another cancer (e.g., kidney–kidney and bladder–prostate) with unclear genetic connection, although rates of positive germline findings were similar in synchronous versus metachronous cancers. Other pairs may represent novel tumor associations that require more comprehensive germline analysis and assessment of exposures (5). Recognition of these novel clusters may have implications for targeted screening and prevention in cancer survivors. For example, many of these cancers have validated screening modalities (e.g., mammogram, prostate specific antigen, colonoscopy, low-dose CT for pulmonary lesions, and skin evaluations), and enhanced surveillance may be considered in survivors of certain cancers if these associations were to be verified.

Few studies have evaluated germline findings in patients with MPC, and none have assessed associations with somatic sequencing. Chan and colleagues examined 1,191 Asian patients with cancer, >80% female, of which 19.4% had MPCs with common tumor pairs including breast–breast, breast–ovary, colon–colon, and colon–endometrial (29). They found that patients with MPC were more likely to have germline findings compared with those with single cancers (34.5% vs. 25.8%) with most common variants in high penetrance genes (>90%; ref. 29). Another study of 212 patients with MPC, 84% female, referred from genetics clinics observed that 20.7% had positive germline findings on clinical testing (30). We previously reported a rate of positive germline findings of 19.7% in an unselected, pan-cancer population (17), with a rate of 17.9% in single primary patients with cancer from that same dataset compared with our rate of 21% in this MPC cohort, P = 0.12. Many prior cohorts were predominantly female, whereas, our cohort is more balanced. In those MPC cases with PVs in highly penetrant genes, genotype–phenotype concordance was high, and the prevalence of LOH was substantial in tumors, particularly in concordant tumors, supporting their etiologic role as “drivers” of these phenotypes. Further studies are needed to evaluate the contribution of moderate/low penetrance genes (31, 32) in the broad spectrum of tumor types observed, as well as gene–gene and gene–environment interactions (4), and the role of genetic modifiers (33, 34), and further work building on this study is ongoing.

Notably, those with no identified PV in known cancer susceptibility genes comprised much of the cohort, suggesting the potential for undiscovered, monogenic or polygenic drivers, or modifiers of tumorigenesis. Whitworth and colleagues performed whole-genome sequencing (WGS) in 460 individuals with MPCs who had undergone genetic assessments and found previously undetected germline PV in moderate/high penetrant genes in 67 (15.2%) of cases, of which 29 had tumor phenotypes discordant with those typically observed (8). In that series, unlike the current and previous series (17), tumor genotyping was not performed to assess LOH to infer a causative role; previously performed WGS in that series (8) also did not detect any clinically relevant noncoding variants, although a small number of structural variants of unclear clinical significance were found. An additional approach to discover shared genomic drivers of MPC would be a comprehensive genomic interrogation and functional assessment of not only the germline but also of multiple tumor genomes from the same patient to identify shared variants or structural alterations, and this work is ongoing.

This study has several limitations. It is comprised of mostly white patients with advanced cancer and a large AJ population (17). There was a potential ascertainment bias in patients offered tumor sequencing, types of tumors represented, and those consenting to receipt of germline results, potentially biasing our analysis. In a previous series (17), adjusting the MSK IMPACT case mix to a population derived case mix resulted in a modest decrease in actionable germline mutation rates observed, suggesting that the rate of germline PV in patients with MPC in the general population is likely to be even lower than the 21% reported here. As an additional limitation, certain tumor histologies (e.g., neuroendocrine tumors) span multiple anatomical sites, complicating analysis. To provide a first approximation of associations, SIR analysis was limited to the subset of the first two cancers occurring, yet, sample sizes for individual tumor pairs were small, resulting in high SIRs with wide confidence intervals. To adjust for this, we sought to normalize the distribution of age at diagnosis for the first primary cancer to reduce bias and performed sensitivity analyses with different weighting factors as well as thresholds of expected frequency to allow consideration of rare cancer associations. As shown by this analysis, strong associations with rare tumors, for example, gall bladder cancers, are evident if thresholds for expected frequency are set to ≥0.5, whereas significance for many other associations diminish as the degree of normalization of the MPC incidence rates is increased. Similarly, all association effects observed here, were impacted by use of single-cancer incidence rates from SEER to calculate expected rates of tumor pairs, which does not account for synchronous cancers and thus may underestimate pairs with hereditary predisposition or common environmental exposure. To address this potential bias, the analysis was adjusted by removing synchronous cancers and highlighting cases with suspected inherited cancer syndromes and/or environmental exposures. Because of these limitations and assumptions, future, prospective studies of cancer patients with a distribution representing the SEER population with long-term follow-up are needed to verify the putative associations, including those of synchronous tumors, reported here. Despite these limitations, this study contains the largest cohort to date of patients with MPC with germline and tumor analysis.

MPC represented a substantial burden of disease in an oncologic pan-cancer cohort of patients undergoing parallel genomic sequencing. Only a small proportion of those patients had germline findings in the limited genes tested, with those PVs observed mostly in high penetrant genes corresponding to clinical phenotype. Standardized analysis of rates of co-incident MPCs revealed novel tumor pairs, not explained by known inherited cancer syndromes or exposures, which could potentially be used clinically to target prevention and screening. More comprehensive evaluation, including sequencing of genomes and/or transcriptomes of primary tumors from individual patients may uncover novel genetic drivers of multiple tumor phenotypes.

Y.L. Liu reports grants from NIH NCI Core grant P30 CA008748 and Robert and Kate Niehaus Center for Inherited Cancer Genomics during the conduct of the study as well as grants from AstraZeneca and GlaxoSmithKline outside the submitted work. K.A. Cadoo reports grants from NCI Core grant P30 CA00874 during the conduct of the study as well as personal fees from Astra Zeneca, MJH Life Sciences, MSD Ireland, and GSK Ireland and other support from MSD Ireland, Immunogen, Pfizer, and Roche Ireland outside the submitted work. Y. Wang reports grants from NIH during the conduct of the study as well as personal fees from New York University outside the submitted work. B. Devolder reports grants from NIH NCI Core Grant during the conduct of the study. M.F. Berger reports personal fees from Eli Lilly and PetDx outside the submitted work. D.B. Solit reports personal fees from Pfizer, Loxo/Lilly Oncology, BridgeBio, Scorpion Therapeutics, Fore Therapeutics, and Vividion Therapeutics outside the submitted work. D.F. Bajorin reports personal fees from Bristol Myers Squibb, Merck, Dragonfly, and Fidia Farmaceutici outside the submitted work. Z.K. Stadler reports other support from Adverum, Alcon, Neurogene Inc., Gyroscope, and RegenexBio outside the submitted work. J. Vijai reports a patent for Diagnosis & Treatment of ERCC3-Mutant Cancer pending. K. Offit is a founder of AnaNeo Pharmaceuticals outside the submitted work; in addition, K. Offit reports a patent for Diagnosis & Treatment of ERCC3-Mutant Cancer pending. No disclosures were reported by the other authors.

Y.L. Liu: Conceptualization, data curation, formal analysis, validation, investigation, visualization, methodology, writing–original draft, project administration, writing–review and editing. K.A. Cadoo: Conceptualization, data curation, formal analysis, validation, investigation, methodology, writing–original draft, project administration, writing–review and editing. S. Mukherjee: Conceptualization, data curation, formal analysis, validation, investigation, visualization, methodology, writing–review and editing. A. Khurram: Conceptualization, data curation, formal analysis, validation, investigation, visualization, methodology, writing–original draft, project administration. K. Tkachuk: Conceptualization, data curation, formal analysis, validation, investigation, visualization, methodology, writing–review and editing. Y. Kemel: Conceptualization, data curation, formal analysis, investigation, visualization, methodology, writing–review and editing. A. Maio: Conceptualization, data curation, formal analysis, validation, investigation, methodology, writing–review and editing. S. Belhadj: Conceptualization, data curation, formal analysis, validation, investigation, visualization, methodology, writing–review and editing. M.I. Carlo: Conceptualization, writing–review and editing. A. Latham: Conceptualization, writing–review and editing. M.F. Walsh: Conceptualization, writing–review and editing. M.E. Dubard-Gault: Conceptualization, writing–review and editing. Y. Wang: Data curation, software, formal analysis, investigation, visualization, methodology, writing–review and editing. A.R. Brannon: Data curation, software, formal analysis, visualization, methodology, writing–review and editing. E. Salo-Mullen: Conceptualization, data curation, formal analysis, investigation, methodology, writing–review and editing. M. Sheehan: Conceptualization, data curation, formal analysis, project administration, writing–review and editing. E. Fiala: Data curation, validation, investigation, methodology, writing-review and editing. B. Devolder: Data curation, investigation, project administration, writing–review and editing. S. Dandiker: Data curation, investigation, project administration, writing–review and editing. D. Mandelker: Conceptualization, data curation, software, formal analysis, validation, investigation, visualization, methodology, writing–review and editing. A. Zehir: Conceptualization, data curation, writing–review and editing. M. Ladanyi: Conceptualization, data curation, writing–review and editing. M.F. Berger: Conceptualization, data curation, formal analysis, writing–review and editing. D.B. Solit: Conceptualization, data curation, writing–review and editing. C. Bandlamudi: Conceptualization, data curation, investigation, methodology, writing–review and editing. V. Ravichandran: Conceptualization, data curation, formal analysis, writing–review and editing. D.F. Bajorin: Conceptualization, writing–review and editing. Z.K. Stadler: Conceptualization, investigation, writing–review and editing. M.E. Robson: Conceptualization, writing–review and editing. J. Vijai: Conceptualization, data curation, formal analysis, writing–review and editing. V. Seshan: Conceptualization, data curation, formal analysis, supervision, investigation, methodology, writing–original draft, writing–review and editing. K. Offit: Conceptualization, resources, formal analysis, supervision, funding acquisition, investigation, writing–original draft, writing–review and editing.

We would like to thank the patients and families that participated in this research study. This work was supported by the Robert and Kate Niehaus Center for Inherited Cancer Genomics and the Sharon Corzine Foundation. MSK and its researchers are supported by the NCI Core grant P30 CA008748. D.F. Bajorin, J. Vijai, and K. Offit are funded by the Bladder SPORE P50CA221745. J. Vijai, K. Offit, A. Khurram, S. Dandiker, and Y. Kemel are funded by the Sharon Corzine Foundation.

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.

1.
Murphy
CC
,
Gerber
DE
,
Pruitt
SL
. 
Prevalence of prior cancer among persons newly diagnosed with cancer: an initial report from the surveillance, epidemiology, and end results program
.
JAMA Oncol
2018
;
4
:
832
6
.
2.
Vogt
A
,
Schmid
S
,
Heinimann
K
,
Frick
H
,
Herrmann
C
,
Cerny
T
, et al
Multiple primary tumours: challenges and approaches, a review
.
ESMO Open
2017
;
2
:
e000172
.
3.
Weir
HK
,
Johnson
CJ
,
Thompson
TD
. 
The effect of multiple primary rules on population-based cancer survival
.
Cancer Causes Control
2013
;
24
:
1231
42
.
4.
Travis
LB
,
Demark Wahnefried
W
,
Allan
JM
,
Wood
ME
,
Ng
AK
. 
Aetiology, genetics and prevention of secondary neoplasms in adult cancer survivors
.
Nat Rev Clin Oncol
2013
;
10
:
289
301
.
5.
Wood
ME
,
Vogel
V
,
Ng
A
,
Foxhall
L
,
Goodwin
P
,
Travis
LB
. 
Second malignant neoplasms: assessment and strategies for risk reduction
.
J Clin Oncol
2012
;
30
:
3734
45
.
6.
Sung
H
,
Hyun
N
,
Leach
CR
,
Yabroff
KR
,
Jemal
A
. 
Association of first primary cancer with risk of subsequent primary cancer among survivors of adult-onset cancers in the United States
.
JAMA
2020
;
324
:
2521
35
.
7.
Mandelker
D
,
Ceyhan-Birsoy
O
. 
Evolving significance of tumor-normal sequencing in cancer care
.
Trends Cancer
2020
;
6
:
31
9
.
8.
Whitworth
J
,
Smith
PS
,
Martin
J-E
,
West
H
,
Luchetti
A
,
Rodger
F
, et al
Comprehensive cancer-predisposition gene testing in an adult multiple primary tumor series shows a broad range of deleterious variants and atypical tumor phenotypes
.
Am J Hum Genet
2018
;
103
:
3
18
.
9.
Cheng
DT
,
Mitchell
TN
,
Zehir
A
,
Shah
RH
,
Benayed
R
,
Syed
A
, et al
Memorial sloan kettering-integrated mutation profiling of actionable cancer targets (MSK-IMPACT): a hybridization capture-based next-generation sequencing clinical assay for solid tumor molecular oncology
.
J Mol Diagn
2015
;
17
:
251
64
.
10.
Cheng
DT
,
Prasad
M
,
Chekaluk
Y
,
Benayed
R
,
Sadowska
J
,
Zehir
A
, et al
Comprehensive detection of germline variants by MSK-IMPACT, a clinical diagnostic platform for solid tumor molecular oncology and concurrent cancer predisposition testing
.
BMC Med Genet
2017
;
10
:
33
.
11.
Report
WG
. 
International rules for multiple primary cancers (ICD-0 third edition)
.
Eur J Cancer Prev
2005
;
14
:
307
8
.
12.
Kundra
R
,
Zhang
H
,
Sheridan
R
,
Sirintrapun
SJ
,
Wang
A
,
Ochoa
A
, et al
OncoTree: a cancer classification system for precision oncology
.
JCO Clin Cancer Inform
2021
:
221
30
.
13.
Sung
H
,
Siegel
RL
,
Rosenberg
PS
,
Jemal
A
. 
Emerging cancer trends among young adults in the USA: analysis of a population-based cancer registry
.
Lancet Public Health
2019
;
4
:
e137
e47
.
14.
Efron
B
,
Tibshirani
RJ
.
An Introduction to the Bootstrap
. 1st ed:
Chapman & Hall/CRC
; 
1994
.
15.
Basen-Engquist
K
,
Chang
M
. 
Obesity and cancer risk: recent review and evidence
.
Curr Oncol Rep
2011
;
13
:
71
6
.
16.
Gritz
ER
,
Talluri
R
,
Fokom Domgue
J
,
Tami-Maury
I
,
Shete
S
. 
Smoking behaviors in survivors of smoking-related and non-smoking-related cancers
.
JAMA network open
2020
;
3
:
e209072
.
17.
Mandelker
D
,
Zhang
L
,
Kemel
Y
,
Stadler
ZK
,
Joseph
V
,
Zehir
A
, et al
Mutation detection in patients with advanced cancer by universal sequencing of cancer-related genes in tumor and normal DNA vs guideline-based germline testing
.
JAMA
2017
;
318
:
825
35
.
18.
Richards
S
,
Aziz
N
,
Bale
S
,
Bick
D
,
Das
S
,
Gastier-Foster
J
, et al
Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the american college of medical genetics and genomics and the association for molecular pathology
.
Genet Med
2015
;
17
:
405
24
.
19.
Cibulskis
K
,
Lawrence
MS
,
Carter
SL
,
Sivachenko
A
,
Jaffe
D
,
Sougnez
C
, et al
Sensitive detection of somatic point mutations in impure and heterogeneous cancer samples
.
Nat Biotechnol
2013
;
31
:
213
9
.
20.
McKenna
A
,
Hanna
M
,
Banks
E
,
Sivachenko
A
,
Cibulskis
K
,
Kernytsky
A
, et al
The Genome Analysis Toolkit: a MapReduce framework for analyzing next-generation DNA sequencing data
.
Genome Res
2010
;
20
:
1297
303
.
21.
Schouten
JP
,
McElgunn
CJ
,
Waaijer
R
,
Zwijnenburg
D
,
Diepvens
F
,
Pals
G
. 
Relative quantification of 40 nucleic acid sequences by multiplex ligation-dependent probe amplification
.
Nucleic Acids Res
2002
;
30
:
e57
.
22.
Hampel
H
,
Bennett
RL
,
Buchanan
A
,
Pearlman
R
,
Wiesner
GL
. 
A practice guideline from the american college of medical genetics and genomics and the national society of genetic counselors: referral indications for cancer predisposition assessment
.
Genet Med
2015
;
17
:
70
87
.
23.
Tung
N
,
Domchek
SM
,
Stadler
Z
,
Nathanson
KL
,
Couch
F
,
Garber
JE
, et al
Counselling framework for moderate-penetrance cancer-susceptibility mutations
.
Nat Rev Clin Oncol
2016
;
13
:
581
8
.
24.
Shen
R
,
Seshan
VE
. 
FACETS: allele-specific copy number and clonal heterogeneity analysis tool for high-throughput DNA sequencing
.
Nucleic Acids Res
2016
;
44
:
e131
.
25.
Donin
N
,
Filson
C
,
Drakaki
A
,
Tan
HJ
,
Castillo
A
,
Kwan
L
, et al
Risk of second primary malignancies among cancer survivors in the United States, 1992 through 2008
.
Cancer
2016
;
122
:
3075
86
.
26.
Coyte
A
,
Morrison
DS
,
McLoone
P
. 
Second primary cancer risk - the impact of applying different definitions of multiple primaries: results from a retrospective population-based cancer registry study
.
BMC Cancer
2014
;
14
:
272
.
27.
Bajdik
CD
,
Abanto
ZU
,
Spinelli
JJ
,
Brooks-Wilson
A
,
Gallagher
RP
. 
Identifying related cancer types based on their incidence among people with multiple cancers
.
Emerg Themes Epidemiol
2006
;
3
:
17
.
28.
Neugut
AI
,
Meadows
AT
,
Robinson
E
.
Multiple primary cancers
:
Lippincott Williams & Wilkins
; 
1999
.
29.
Chan
GHJ
,
Ong
PY
,
Low
JJH
,
Kong
HL
,
Ow
SGW
,
Tan
DSP
, et al
Clinical genetic testing outcome with multi-gene panel in Asian patients with multiple primary cancers
.
Oncotarget
2018
;
9
:
30649
60
.
30.
Whitworth
J
,
Hoffman
J
,
Chapman
C
,
Ong
KR
,
Lalloo
F
,
Evans
DG
, et al
A clinical and genetic analysis of multiple primary cancer referrals to genetics services
.
Eur J Hum Genet
2015
;
23
:
581
7
.
31.
Mandelker
D
,
Kumar
R
,
Pei
X
,
Selenica
P
,
Setton
J
,
Arunachalam
S
, et al
The landscape of somatic genetic alterations in breast cancers from CHEK2 germline mutation carriers
.
JNCI Cancer Spectrum
2019
;
3
:
pkz027
.
32.
Weigelt
B
,
Bi
R
,
Kumar
R
,
Blecua
P
,
Mandelker
DL
,
Geyer
FC
, et al
The landscape of somatic genetic alterations in breast cancers from ATM germline mutation carriers
.
J Natl Cancer Inst
2018
;
110
:
1030
4
.
33.
Barnes
DR
,
Rookus
MA
,
McGuffog
L
,
Leslie
G
,
Mooij
TM
,
Dennis
J
, et al
Polygenic risk scores and breast and epithelial ovarian cancer risks for carriers of BRCA1 and BRCA2 pathogenic variants
.
Genet Med
2020
;
22
:
1653
66
.
34.
Taeubner
J
,
Wieczorek
D
,
Yasin
L
,
Brozou
T
,
Borkhardt
A
,
Kuhlen
M
. 
Penetrance and expressivity in inherited cancer predisposing syndromes
.
Trends Cancer
2018
;
4
:
718
28
.