Data to be presented at the annual meeting of the American Society of Clinical Oncology (ASCO) on Sunday, June 3, suggest that African American men with localized prostate cancer may be less likely that Caucasian men to respond well to active surveillance as a management strategy. However, this conclusion comes from a retrospective analysis of data from a relatively small, single-institution case series.
Mitchell et al. conducted a retrospective review of data from a cohort of 222 prostate cancer patients, all diagnosed by biopsy with low-risk disease and managed at the Duke Prostate Cancer between January 2005 and September 2011.
This retrospective data analysis shows that:
- 162/222 patients (73 percent) were Caucasian.
- 51/222 patients (23 percent) were African American.
- Average (median) follow-up was 25.4 months.
- There were no significant differences between Caucasian and African American patient groups with regard to age, household income, body mass index (BMI), PSA level, clinical stage, family history, prostate volume, number of cores with cancer, Gleason grade at initial biopsy, number of PSA tests performed after initiation of active surveillance, or number of biopsies performed after initiation of active surveillance.
However, men in the African American cohort
- Were more likely than Caucasians to demonstrate progression on follow-up biopsies (72.7 vs. 63.8 percent).
- Were less likely than Caucasians to “fail by choice” (9.1 vs. 14.9 percent), i.e., opt out of active surveillance to have active treatment.
- Had a shorter time than Caucasians to failure of active surveillance for any reason (hazard ratio [HR] = 1.74, p = 0.045).
- Demonstrated a greater likelihood than Caucasians of Gleason scores of 8 to 10 on follow-up biopsy (10 vs. 2.5 percent, p = 0.08).
Overall, on multivariate analysis, there were three significant predictors of risk for failure of active surveillance for any cause:
- African American race (HR = 1.76, p = 0.058)
- Initial PSA level (HR = 1.90, p = 0.031)
- Number of cores shown to contain cancer on initial biopsy (HR = 1.29, p = 0.013)
The authors conclude that, in this cohort of men, African American race was associated with higher risk for failure of active surveillance (due to biopsy progression and the presence of higher grade cancer).
As indicated above, however, this is a small, retrospective data analysis, and additional information will be necessary before we will know if this outcome is replicated in other studies.
It also occurs to us that dietary factors may be relevant to this outcome. For example, do African American males in North Carolina have diets that are higher in fat content than their Caucasian counterparts, which might then contribute to the probability of disease progression after diagnosis? If that was to be the case, it is one more reason to consider the idea of cholesterol-lowering therapy as a possible adjunct to active surveillance as a method to lower the risk of disease progression among men on active surveillance protocols (at least in men with elevated cholesterol levels at the time of diagnosis).