Active Surveillance Found Feasible Among African Americans With Low-Risk Prostate Cancer

Brent Rose, MD

African American men with low-risk prostate cancer who received active surveillance had a statistically significant increased 10-year cumulative incidence of disease progression and definitive treatment compared with non-Hispanic white men, according to findings from a retrospective analysis published in JAMA.¹

At 10 years, the cumulative incidence rate of disease progression was 59.9% among African American men (n = 2280) vs 48.3% among White men (n = 6446; difference, 11.6%; 95% CI, 9.2%-13.9%; Gray P < .001). The 10-year cumulative incidence rate of definitive treatment was 54.8% among African American men vs 41.4% among white men (difference, 13.4%; 95% CI, 11.0%-15.7%; Gray P < .001).

Despite this, metastasis and prostate cancer–specific mortality was not significantly different between African American and White men, at a median follow-up of 7.6 years.

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

The retrospective study included 8726 men with low-risk prostate cancer who had received active surveillance, which was defined as having no definitive treatment within the first year of diagnosis and at least 1 additional surveillance biopsy after the first diagnostic biopsy.1 The additional biopsy was required as a means to differentiate between active surveillance and watchful waiting.

Patient data were extracted from the US Veterans Health Administration’s Corporate Data Warehouse, which contains the electronic health records of more than 9 million veterans.

All patients had to have low-risk prostate cancer, defined as a Gleason score of 6 or less, a clinical tumor stage of 2A or less, and a prostate-specific antigen (PSA) level less than 10 ng/dL. Patients who had prior pelvic radiation, were missing predetermined covariates, or were neither African American nor White were not included in the study. Based on fixed categories, each veteran self-reported their race and ethnicity.

A total 26.1% of men on study were African American men compared with 73.6% of those who were White. Notable baseline characteristics showed that African American men had a significantly lower median age at diagnosis compared with White men (63.2 years vs 65.5 years, respectively). Additionally, African American men were more likely to present with a lower clinical tumor stage at diagnosis vs White men.

Compared with White men, African American men were more likely to have used antihypertensive and antiplatelet medications within the prior year. They also had significantly higher rates of alcohol, substance, and tobacco use disorders within the prior year vs White men.

Regarding household characteristics, African American men were significantly more likely to live in the southern region of the United States and in areas with lower zip code-level median household income and educational levels, defined by the achievement of at least a Bachelor’s degree, compared with White men.

The median number of tumor biopsies was 2 among African American men and White men. However, the difference was statistically significant (P = .02). The median number of PSA tests (n = 12; P = .34) and the median time to second biopsy (n = 3.5; P = .87) were not significantly different between groups.

No significant difference in the length of follow-up was reported between African American men and White men, respectively (7.4 years; interquartile range, 5.7-9.6; range, 0.2-18.2; 7.6 years; interquartile range, 5.7-9.9; range, 0.2-19.2; P = .14). However, 21.9% of African American men (n = 499) and 24.5% of White men (n = 1582) had at least 10 years of follow-up.

During follow-up, 1156 African American men and 2610 White men experienced disease progression. Multivariable competing risks regression testing revealed that African American men were significantly more likely to experience disease progression (sub-distribution HR [SHR], 1.3; 95% CI, 1.2-1.4; P < .001), a PSA level of 10 ng/dL (SHR, 1.3; 95%CI, 1.1-1.5; P < .001), and a Gleason score greater than 6 (SHR, 1.4; 95% CI, 1.2-1.5; P < .001) after diagnosis.

A total of 1137 African American men and 2438 White men received definitive treatment. The multivariable competing risks regression analysis confirmed that African American men were more likely to receive definitive treatment compared with White men (SHR, 1.3; 95% CI, 1.2-1.4; P < .001).

Within the allotted follow-up period, 109 men experienced progression to metastatic prostate cancer. Of these men, 30 were African American and 79 were White. The cumulative incidence rate of metastasis was 1.5% vs 1.4%, respectively; the difference was not found to be statistically significant (difference, 0.1%; 95% CI, -0.4% to 0.6%; Gray P = .49).

With regard to prostate cancer mortality, 87 patients died from prostate cancer within the confines of the follow-up period. Of these patients, 22 were African American and 65 were White, making the cumulative incidence of prostate–cancer specific mortality rates 1.1% and 1.0%, respectively (difference, 0.1%; 95% CI, -0.4%-0.6%; Gray P = .82). Because this difference was not found to be statistically significant, the study authors concluded that African American men were not significantly more likely to experience prostate cancer–specific mortality compared with White men.

Non-prostate cancer–related death was reported in 387 African American patients and 1265 White patients. At 10 years, the cumulative incidence rates of all-cause mortality were 22.4% and 23.5%, respectively (difference, 1.1%; 95% CI, -0.9%-3.1%; Gray P = .09), which was not found to be a statistically significant difference per a multivariate Cox proportional hazards regression model.

“Physicians and patients should discuss active surveillance for African American men with low-risk prostate cancer,” said Rose, who is also a radiation oncologist at Moores Cancer Center at UC San Diego Health.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.”

Limitations of the study include that it was a retrospective analysis in which no follow-up protocol for active surveillance was established. Additionally, after the repeated biopsy was performed, subsequent PSA testing, biopsies, and treatment decisions were made at the discretion of the physicians and patients.

Other limitations included no prespecified method or timing of clinical ascertainment of metastases, manual medical record review, lack of generalizability of findings, and potential type 1 errors due to multiple comparisons between several study end points.

As such, further validation of these findings is needed. Additionally, longer-term follow-up is needed to better assess mortality risk, concluded Rose and co-authors.

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. UC San Diego News Center. November 3, 2020. Accessed November 4, 2020. https://bit.ly/3jW2i0c.