(BSPOT02) A prospective cohort study of risk factors associated with prostate cancer incidence in predominantly low-income Black Americans

Background: Prostate cancer is the most common cancer in men. In the United States, Black men are disproportionally affected by prostate cancer, experiencing an almost two-fold risk in both prostate cancer incidence and mortality compared with White men.

Objectives: We investigated racial disparities and demographic, geographic, medical and behavioral factors related to prostate cancer risk in a low-income population.

Methods: Our study utilized prospectively collected data from Southern Community Cohort Study (SCCS) male participants, recruited primarily from Community Health Centers (CHCs) located in twelve southeastern states from 2002-2009. The final study population consisted of 30,911 men, 70% of whom self-identified as Black; participants with a previous cancer history (other than non-melanoma skin cancer) were excluded. All characteristics analyzed were ascertained at enrollment, and cancer and vital status were followed up through linkages with state cancer registries and National Death Index. We calculated prostate cancer incidence rates by racial group and stratified by household income.

Results: A total of 1,367 prostate cancer cases (1,058 Blacks and 309 Whites) were accrued within an average follow-up time of 11.3 years. Age-standardized cancer incidence per 100,000 person-years were 698.8 for Black men and 395.2 for White men after excluding those with a follow-up time less than one month. The incidence rates increased with higher household income levels for both racial groups. This racial disparity persisted in the final multivariate model adjusted for confounders and other risk factors. Black men had a hazard ratio of 2.24 (95% CI 1.95-2.58) versus White men for overall prostate cancer risk after adjustment for age, smoking status and packyears, red meat consumption, personal medical history, total energy intake, and enrollment source. Higher income levels, a history of benign prostatic hyperplasia (BPH), having co-morbidities other than diabetes, and a history of prostate-specific antigen (PSA) testing also contributed to an increased risk, and all of these factors (except for BPH) remained statistically significant in Black men only.

Conclusions: Within a cohort of predominantly Black men and those with a relatively low socioeconomic status, we observed similar racial disparities of prostate cancer risk as the general population. Individual-level factors were also identified to be associated with higher prostate cancer risk within this group, overall and among Black men. The persistence of disparity with adjustment for multiple environmental and behavioral factors suggest a potential biologic basis.