Disease Progression More Likely in African American Men With Prostate Cancer, Study Shows

A statistically significant increase in the 10-year cumulative incidence of disease progression and definitive treatment among African American men compared with non-Hispanic Caucasian men with low-risk prostate cancer, according to findings from a retrospective cohort study.¹

The purpose of this study was to compare the clinical outcomes of these 2 patient populations with low-risk prostate cancer who are managed with active surveillance considering the lack of understanding regarding whether African American men harbor more aggressive disease compared with non-Hispanic Caucasian counterparts. It is unclear at this time if active surveillance is an appropriate approach to this population, which is what this study aimed to determine.

“Our research provides evidence that active surveillance is safe for African American men,” said Brent Rose, MD, assistant professor in the Department of Radiation Medicine and Applied Sciences at University of California San Diego School of Medicine, in a statement.² “This means more African American men can avoid definitive treatment and the associated side effects of urinary incontinence, erectile dysfunction, and bowel problems.”

Data from the United States Veterans Health Administration Health Care System of African American and non-Hispanic Caucasian men who were diagnosed with low-risk disease between January 1, 2001, and December 31, 2015, and were managed with active surveillance. The final follow-up was conducted on March 31, 2020. Patients who had no definitive treatment within 1 year of diagnosis with at least 1 additional surveillance biopsy were considered to have received active surveillance.¹

End points of interest in this study included disease progression, definitive treatment, metastasis, prostate cancer-specific mortality, nonprostate cancer-specific mortality, and call-cause mortality. Overall, 8726 patients were included in the study, of which 2280 (26.1%) were African American and 6447 (73.9%) were Caucasian. The median age at diagnosis in the African American population was lower at 63.2 years compared with the Caucasian population at 65.5 years, and the African American group also were significantly more likely to present with a lower clinical tumor stage.

The African American population also appeared to be significantly more likely to use antihypertensive and antiplatelet medications, and had significantly higher rates of alcohol, substance, and tobacco use disorders. This population also was significantly more likely to live in the South and in areas with lower zip code-level median household income and education levels.

Overall, 2081 patients were followed for at least 10 years, which included 499 (21.9%) in the African American group and 1582 (24.5%) in the Caucasian arm. During follow-up, 3766 patients had disease progression, including 1156 from the African American arm and 2610 in the Caucasian arm. The cumulative incidence of disease progression at 10 years was 59.9% versus 48.3% in the African American and Caucasian populations, respectively, which demonstrated a difference of 11.6% (95% CI, 9.2%-13.9%; P <.001).

The African American men were significantly more likely to experience disease progression with a subdistribution hazard ratio (SHR) of 1.3 (95% CI, 1.2-1.4; P <.001). African American men were also significantly more likely to experience a PSA level of 10 ng/dL or greater (SHR, 1.3; 95% CI, 1.1-1.5; P <.001) and to experience a Gleason score greater than 6 after diagnosis (SHR, 1.4; 95% CI, 1.2-1.5; P <.001).

Definitive treatment was administered in 3575 patients, including 1137 in the African American arm and 2438 in the Caucasian arm, and among these groups, the cumulative incidence of definitive treatment at 10 years was, respectively, 54.8% and 41.4%, which demonstrated a difference of 13.4% (95% CI, 11.0%-15.7%; P<.001). African American men were significantly more likely to receive definitive treatment in a multivariable competing risks regression (SHR, 1.3; 95% CI, 1.2-1.4; P <.001).

Metastatic prostate cancer affected 109 men during the study follow-up, which included 30 African American men and 79 Caucasian men. The cumulative incidence of metastasis at 10 years was 1.5% in the African American arm and 1.4% in the Caucasian arm for a difference of 0.1% (95% CI, -0.4-0.6%; P =.49). African American patients were not significantly more likely to experience metastasis in a multivariable competing risks regression (SHR, 1.2; 95% CI, 0.8-1.9; P =.48).

Overall, 87 deaths from prostate cancer were observed in the study, which included 22 in the African American Arm and 65 in the Caucasian arm, and the cumulative incidence or prostate cancer-specific mortality at 10 years, respectively, was 1.1% and 1.0% for a difference of 0.1% (95% CI, -0.4%-0.6%; P =.82). In the multivariable competing risks regression, the African American population was not significantly more likely to experience prostate cancer=specific mortality (SHR, 1.2; 95% CI, 0.7-2.1; P =.82).

Nonprostate cancer deaths were observed in 1652 men, 387 from the African American arm, and 1265 in the Caucasian arm. The cumulative incidence of nonprostate cancer death at 10 years was 21.2% among the African American population and 22.4% in the Caucasian arm for a difference of 1.2% (95% CI, -0.7%-3.2%; P=.14).

African American men were not significantly more likely to experience nonprostate cancer mortality in the multivariable competing risks regression (SHR, 1.0; 95% CI, 0.9-1.1; P =.70). Among the African American and Caucasian populations, respectively, 409 and 1330 patients experience death from any cause for a total of 1739, and the cumulative incidence of all-cause mortality at 10 years was 22.4% and 23.5% for a difference of 1.1% (95% CI, -0.9%-3.1%; P =.09). African American men were not significantly more likely to experience all-cause mortality (SHR, 1.0 [95% CI, 0.9-1.1]; P = .85) in the variable Cox proportional hazards regression.

The preferred treatment approach for many patients with low-risk prostate cancer is active surveillance in an attempt to avoid or delay the toxicities of definitive therapy, and the study shows that African American men should not be excluded from these protocols. However, changes and improvements in patient selection, as well as closer follow-up is needed to maintain favorable outcomes among all patients with low-risk disease.

“Physicians and patients should discuss active surveillance for African American men with low-risk prostate cancer,” stated Rose, a radiation oncologist at Moores Cancer Center at UC San Diego Health and senior author on the paper.² “Overall outcomes are similar among African American men and white men. However, due to the increased risk of progression, African American men need to be carefully followed and promptly treated if their cancer progresses.”

Longer-term follow-up is needed to provide a better understanding of the mortality risk among African American men versus non-Hispanic Caucasian men with low-risk prostate cancer.

_References

_{1. Deka R, Courtney PT, Parsons JK, et al. Association Between African American Race and Clinical Outcomes in Men Treated for Low-Risk Prostate Cancer With Active Surveillance. Jama. 2020;324(17):1747-1754. doi: 10.1001/jama.2020.17020}

_{2. Active Surveillance Safe for African Americans With Low-Risk Prostate Cancer. News Release. University of California San Diego. November 3, 2020. Accessed November 4, 2020. https://bit.ly/32d9Q8x}