Tobacco use and prostate cancer in Blacks and Whites in the United States
Prostate cancer occurs more frequently in Blacks than Whites in the United States. A population-based case-control study which investigated the association between tobacco use and prostate cancer risk was carried out among 981 pathologically confirmed cases (479 Blacks, 502 Whites) of prostate cancer, diagnosed between 1 August 1986 and 30 April 1989, and 1,315 controls (594 Blacks, 721 Whites). Study subjects, aged 40 to 79 years, resided in Atlanta (GA), Detroit (MI), and 10 counties in New Jersey, geographic areas covered by three, population-based, cancer registries. No excesses in risk for prostate cancer were seen for former cigarette smokers, in Blacks (odds ratio [OR]=1.1, 95 percent confidence interval [CI]=0.7–1.5) and in Whites (OR=1.2, CI=0.9–1.6), or for current cigarette smokers, in Blacks (OR=1.0, CI=0.7–1.4) and in Whites (OR=1.2, CI=0.8–1.7). Increases in risk were noted for smokers of 40 or more cigarettes per day, among former (OR=1.4, CI=1.0–1.5) and current (OR=1.5, CI=1.0–2.4) smokers. Duration of cigarette use and cumulative amount of cigarette use (pack-years) were not associated with prostate cancer risk for Blacks or Whites. By age, only the youngest subjects, aged 40 to 59 years, showed excess risk associated with current (OR=1.5, CI=1.0–2.3) and former (OR=1.7, CI=1.1–2.6) use of cigarettes, but there were no consistent patterns in this group according to amount or duration of smoking. Risks also were not elevated for former or current users of pipes, cigars, or chewing tobacco, but the risk associated with current snuff use was OR=5.5 (CI=1.2–26.2). This subgroup finding may have been due to chance. The results of the present study may be consistent with a small excess risk for prostate cancer associated with tobacco use, but the lack of consistent findings in population subgroups and the lack of a clear dose-response relationship argue more strongly that no causal association exists. The data do not indicate that the Black-White difference in prostate cancer risk is related to tobacco use.