Black Men Derive Improved Outcomes With Definitive Radiotherapy in Localized Prostate Cancer

Ting Martin Ma, MD, PhD

Black men with localized prostate cancer who had been treated with definitive radiotherapy had a lower likelihood of experiencing biochemical recurrence, distant metastasis, and prostate cancer–specific mortality compared with White men despite having more aggressive disease, according to findings from a meta-analysis that were published in JAMA Network Open.¹

The results showed that Black men had a lower risk of biochemical recurrence (subdistribution hazard ratios [sHR], 0.88; 95% CI, 0.58-0.91), distant metastasis (sHR, 0.72; 95% CI, 0.58-0.91), and prostate cancer–specific mortality (sHR, 0.72; 95% CI, 0.54-0.97) vs White men.

“The findings of this meta-analysis suggest that Black men enrolled in randomized clinical trials present with more aggressive disease but have better biochemical recurrence, distant metastasis, and prostate cancer–specific mortality with definitive radiotherapy compared with White men, suggesting that other determinants of outcome, such as access to care, are important factors of achieving racial equity,” wrote Ting Martin Ma, MD, PhD, a resident physician at UCLA Health, and coauthors in the study publication.

Black men have a 2-fold increased risk of dying from prostate cancer vs White men. However, race-specific differences in response to initial treatment are not well documented.

To better understand if such differences exist, investigators compared overall and treatment-specific outcomes of Black and White men with localized prostate cancer receiving definitive radiotherapy.

All data was collected from 7 published randomized clinical trials of definitive radiotherapy for patients with localized prostate cancer that reported on treatment-specific and overall outcomes led by the NRG Oncology/Radiation Therapy Oncology Group between January 1, 1990, and December 31, 2010. The meta-analysis was conducted from July 1, 2019, to July 1, 2021.

sHRs of biochemical recurrence, distant metastasis, and prostate cancer-specific mortality served as the primary end points for evaluation.

A total of 8814 patients (Black, n = 1630; 18.5%; White, n = 7184; 81.5%) were included. The mean age was 69.1 years (standard deviation, 6.8).

The median follow-up among surviving patients was 10.6 years (interquartile range [IQR], 8.0-17.8).

Most patients had low- (n = 1748; 19.8%) and intermediate-risk disease (n = 4263; 48.4%) according to the National Comprehensive Cancer Network; the remaining patients had high-risk disease (n = 2803; 31.8%).

Black men were significantly younger than White men at presentation (median IQR, 68 years; 62-73 vs IQR, 71 years; 66-74, respectively; P < .001). Black men were also significantly more likely to have high-risk disease (n = 622; 38.2%) vs White men (n = 2181; 30.4%; P < .001), higher prostate-specific antigen (PSA) levels (median IQR, 10.3 ng/mL; 6.2-19.1 vs 8.4 ng/mL; 5.7-13.2, respectively; P < .001), and Gleason scores of 8 to 10 (n = 262/1608; 16.3% vs n = 997/7086; 14.1%, respectively; P = .03).

No difference was reported in the number of Black vs White patients, respectively, with cT3-4 disease (n = 259; 17.0% vs n = 1296; 18.7%; P = .10). Though, Black men were more likely to have cT1 disease (n = 772; 50.5% vs n = 2857; 41.3%; P < .001).

Additional results showed that Black men had a lower risk of biochemical recurrence and distant metastasis if they were aged 65 years or younger, had high-risk disease, PSA levels greater than 20 ng/mL, and had received radiotherapy with short-term androgen deprivation therapy.

Notably, Black men had lower absolute unadjusted 10-year cumulative incidence rates of biochemical recurrence (40.5%) vs White men (44.6%; P = .006), as well as lower rates of distant metastasis (8.4% vs 11.6%, respectively; P = .005), and prostate cancer–specific mortality (4.5% vs 6.4%, respectively; P = .03).

The 10-year rates of all-cause mortality and death or distant metastasis were similar among Black men and White men (all-cause mortality: 39.8% vs 41.2%, respectively; P = .43; death or distant metastasis: 41.5% vs 43.6%, respectively; P = .40).

No significant differences in time to all-cause mortality were identified between the cohorts (HR, 0.99; 95% CI, 0.92-1.07; P = .87).

After adjustment, Black race continued to be significantly associated with improved biochemical recurrence (adjusted sHR, 0.79; 95% CI, 0.72-0.88; P < .001), distant metastasis (adjusted sHR, 0.69; 95% CI, 0.55-0.87; P = .002), and prostate cancer-specific mortality (adjusted sHR, 0.68; 95% CI, 0.50-0.93; P = .01).

“These results provide high-level evidence to question the belief that prostate cancer among Black men necessarily portends a worse prognosis compared with White men. This belief may be a factor in differences in the approach to cancer therapy, thereby leading to the use of more aggressive treatments than might be necessary, which carry greater risks of decreasing the quality of life and distracting attention from other important factors associated with outcome and sources of disparity, such as access to care,” concluded the study authors.

Reference

1. Ma TM, Romero T, Nickols NG, et al. Comparison of response to definitive radiotherapy for localized prostate cancer in Black and White men: a meta-analysis. JAMA Netw Open. 2021;4(12):e2139769. doi:10.1001/jamanetworkopen.2021.39769