No Association Found Between Black Race and Risk of Skeletal-Related Events in mCRPC

A study published in Cancer found no association between Black race and risk of skeletal-related events (SREs) and overall mortality in men with newly diagnosed, bone metastatic castration-resistant prostate cancer (mCRPC).

Instead, researchers indicated that these data suggest that efforts to better understand the basis for the excess risk of aggressive prostate cancer in Black men should focus on cancer development and progression in those with early-stage disease.

“To the best of our knowledge, the prognostic impact of race on the outcomes of men with more advanced forms of prostate cancer remains understudied,” the authors wrote. “We observed no association between Black race and the risk of SREs and overall mortality, indicating that once men develop bone mCRPC, race may not be an adverse prognostic factor.

In this retrospective study, investigators assessed patients from 8 Veterans Affairs (VA) hospitals who were newly diagnosed with bone mCRPC in the year 2000 or later. Overall, 837 patients with bone mCRPC were identified, including 232 Black patients (28%) and 605 (72%) non-Black patients.

Black men were more likely to have more bone metastases at the time of diagnosis compared with no-Black men (29% vs 19% with ≥10 bone metastases; P = 0.021) and to have higher prostate-specific antigen (41.7 ng/mL vs 29.2 ng/mL; P = 0.005) and a longer time from diagnosis of CRPC to metastasis (17.9 months vs 14.3 months; P < 0.01). Black and non-Black men also differed with regard to the location of their primary treatment center (P < 0.001).

Among those who did not die, the median follow-up after diagnosis of metastasis was 25.9 months (range, 12.0-46.4 months). During follow-up, 287 patients (35%) experienced SREs. There were no differences observed in the risk of developing an SRE between Black and non-Black individuals (log-rank, P = 0.35). The results demonstrated little change on multivariable analysis, with no differences observed in SRE risk (hazard ratio [HR], 0.80; 95% CI, 0.59-1.07; P = 0.13) between Black and non-Black people.

Investigators also evaluated mortality rates between Black and non-Black people from the time of diagnosis of bone mCRPC. In total, 740 men (88%) died during follow-up. On crude analysis, race was found to be unrelated to overall mortality (log-rank, P = 0.60). Furthermore, there remained no differences on multivariate analyses with regard to overall mortality between Black and non-Black men with bone mCRPC (HR, 0.87; 95% CI, 0.73-1.04 [P = 0.13]). However, with the HR being < 1, researchers suggested the possibility of better outcomes.

“These current data suggest that race does not have a negative prognostic effect in patients with mCRPC,” the authors wrote. “These results are consistent with prior studies from our group using the same cohort, wherein we identified predictors of SREs and race did not enter the model.”

Notably, though the inclusion of only patients from VA hospitals was a strength in regard to evaluation of patients who have equal assess, it could have possibly made the results difficult to extrapolate to other patient populations. In addition, because these results were observed outside of a clinical trial setting, the various anticancer therapies used to treat patients were not standardized.

“Moreover, along with our mortality data, these data add to the increasing evidence that the greatest benefits to understanding racial disparities in prostate cancer would occur if efforts are focused on cancer development and progression in patients with early-stage disease,” the authors wrote.

Reference:

Patel DN, Howard LE, De Hoedt AM, et al. Race Does Not Predict Skeletal-Related Events and All-Cause Mortality in Men With Castration-Resistant Prostate Cancer. Cancer. doi: 10.1002/cncr.32933.