Abstract
Introduction: The incidence and/or mortality rates for the major cancers in the U.S. are significantly higher for African Americans (AA) than they are for whites. This difference has been observed primarily in cancers of the prostate gland, lung, breast (premenopausal only), and large intestine. These most prevalent cancers account for 53% of all malignant tumors in blacks and 50% in whites. In this study, we report a descriptive epidemiologic analysis of the black-white variations seen in the trends, incidence, age specific rates, and survival of renal cancer.
Methods: Data were obtained from NCI's Surveillance, Epidemiology, and End Results Program (SEER) for the years 1973–2005. Using SEER Registry 9, there were 6,495 cases of renal cell carcinoma reported in AA and 57, 222 reported in whites. Cases were compared by linear and by log-log plots of the age of diagnosis and age specific incidence rates. The two main histological types of renal cancer clear cell carcinoma and papillary carcinoma_were considered. Rates are expressed as number of cases per 100,000 persons.
Results: The overall incidence rate of renal cancers was significantly higher in AA men (15.9) and women (7.7), respectively, than in White men (13.5) and women (6.5). The mean age of diagnosis for AA and whites was 58.9 and 63.3 years, respectively. In both AA and whites, the trend in renal cancers has been consistently increasing since 1973 at the same rate. The annual increase was statistically significant in both men and women in the two groups. However, in both AA and whites, the increasing trend was limited to the clear cell type, the most common type in all groups. In contrast, the rates of papillary and non-clear cell tumors have remained constant since 1973 in both AA and whites. The age specific rates of renal cell carcinomas were higher in AA men than in white men, but were similar in AA and White women. These rates were significantly greater in men than in women. The 5-year relative survival rate was 64% for men and 66% for women, independent of racial group. Consequently, there was no difference in relative survival when AA were compared to whites in the SEER Program.
Conclusions: In both men and women, renal cell cancer is more common in AA than in whites. The incidence rate of renal cancer has consistently increased since 1973 in both AA and in whites, although this increase has affected only the clear cell histological type. This progressive increase in clear cell but not in the papillary type suggests that subtypes of renal cancer represent different populations with respect to carcinogenic pathways. Cancers of the kidney need to be considered in any analysis of health disparities because of their higher incidence in AA. Incident and susceptibility differences in renal cancers among racial and gender groups may have biologic and non-biologic factors and are unresolved.
Second AACR International Conference on the Science of Cancer Health Disparities— Feb 3–6, 2009; Carefree, AZ