Black men have significantly higher rates for prostate cancer-specific mortality than non-Hispanic white men, researchers concluded in a new study published in Cancer Medicine. While numerous papers have investigated the underlying reasons for the excess risk, the new findings suggest that factors beyond socioeconomic disparities are responsible.
Using their institutional database spanning over 25 years, Kosj Yamoah, MD, PhD, and colleagues from the Moffitt Cancer Center & Research Institute in Tampa, Florida, evaluated prostate cancer (PCa) outcomes and ruled out some known confounders. Of 7307 patients diagnosed with PCa during 1989 to 2015, 432 died from their disease.
In a multivariate competing risk model, black men had a significant 62% greater risk for PCa-specific mortality compared with white men. For black patients diagnosed after age 60, the relative risk of death due to PCa more than doubled.
The models were specifically designed to rule out important clinical and demographic risk factors, including age at diagnosis, year of diagnosis (e.g., pre- or post-PSA era), tobacco exposure, and health insurance (as a proxy for socioeconomic status). They also factored in comorbidity index, stage of cancer at presentation, biopsy-determined T stage, and treatment modality. The results held after exclusion of cases with distant metastasis at diagnosis.
Overall mortality did not differ between blacks and whites, the team reported. Of the original cohort, 1872 men died from causes other than PCa over a median 106 months of follow-up.
Black men tended to be diagnosed with PCa at a younger age: median 60 vs 65 years. In addition, a greater proportion had one or more comorbidities: 13.6% vs 7.5%.
The authors acknowledged some study limitations. For example, they did not include PSA values and Gleason scores in their analysis because this information was either incomplete or missing for most of the older cases. In addition, possible misclassification of clinical T stage was a potential limitation, as T stage upgrading occurs frequently after patients receive initial treatment, they noted.
Williams VL, Awasthi S, Fink AK, et al. African-American men and prostate cancer-specific mortality: a competing risk analysis of a large institutional cohort, 1989–2015. Cancer Med. 2018 [Published online ahead of print.]