RICHMOND, VA — African American men have historically had poorer prostate cancer biochemical and survival outcomes than Caucasians. The question is why?

So asked a new study suggesting that emerging data point to nononcologic factors for much of this disparity. The report in the Brachytherapy journal noted that prior evidence has suggested an association between a transient prostate specific antigen (PSA) bounce and improved biochemical control. Yet, wrote researchers from the Hunter Holmes McGuire VAMC and Virginia Commonwealth University, both in Richmond, racial differences in that relationship have remained relatively unexplored.1

To remedy that, the study team identified 4,477 men treated for low- or intermediate-risk prostate cancer within the VA from 2000 to 2010 with brachytherapy alone or in combination with external beam radiotherapy without androgen deprivation. The researchers used longitudinal PSA data to define to biochemical failure and PSA bounce, exploring racial differences in the relationship between the PSA bounce and time to biochemical failure.

Overall, the study revealed, 31% of the sample experienced a PSA bounce, with African Americans more likely to experience a bounce (42%) compared with Caucasians (29%); p < 0.001.

“Despite this, African Americans had a higher likelihood of biochemical failure (hazard ratio [HR] 1.4; p = 0.006),” the authors wrote. “However, African American men experiencing a PSA bounce were less likely to experience a biochemical failure (HR = 0.64; p = 0.046), whereas this relationship was not statistically significant for Caucasians (HR = 0.78; p = 0.092).”

They added that, on multivariate analysis, African Americans receiving brachytherapy alone were most sensitive to the protective benefit of the PSA bounce (HR = 0.64).

“A PSA bounce was associated with improved biochemical control among patients receiving brachytherapy as part of their treatment for low- or intermediate-risk prostate cancer at the VA,” the researchers concluded. “African American men treated with brachytherapy had a particularly pronounced biochemical control benefit of a PSA bounce.”

1. Slade AN, Dahman B, Chang MG. Racial differences in the PSA bounce inpredicting prostate cancer outcomes after brachytherapy: Evidence from theDepartment of Veterans Affairs. Brachytherapy. 2019 Oct 11. pii:S1538-4721(19)30448-9. doi: 10.1016/j.brachy.2019.08.008. [Epub ahead of print]PubMed PMID: 31611160.