African Americans and the risk of reclassification in Active Surveillance

From the Lin Group, Division of Public Health Sciences

Active surveillance among men with low-risk prostate cancer (PCa) has become more widely accepted in recent years.  Multiple publications have supported the utilization of active surveillance (AS) as alternative to immediate treatment among men with favorable-risk PCa. Although use of AS is increasing, its current rates are lower among African Americans compared to the Caucasian Americans in the US. The appropriateness of AS for African American men has been unclear. African American men, who have a higher prostate cancer incidence and mortality than Caucasian American men, have been underrepresented in patient cohorts demonstrating favorable surveillance outcomes for men with low-risk prostate cancer. In a recent study from Dr. Daniel Lin’s group in the Division of Public Health Sciences, researchers investigated the association of race in African American men with risk of pathologic reclassification among men on AS. The results were published in The Journal of Urology.

Dr. Jeannette Schenk, a senior staff scientist described the rationale for the study: “There have been some conflicting reports as to whether active surveillance is an appropriate option for African American men. In particular, one recent study reported a significant increased risk of pathologic reclassification among African American men on active surveillance. However, studies evaluating the associations between race and active surveillance outcomes may be subject to several potential sources of bias. In particular, racial disparity in the intensity of surveillance, such as the frequency of PSA tests and biopsies), or how surveillance is conducted (such as the number of biopsy cores sampled or whether multiparametric magnetic resonance imaging (mp-MRI) was used) could impact the likelihood of detecting progression events on active surveillance.”

Using data from the Canary Prostate Active Surveillance Study (PASS), a large, prospective multi-institutional active surveillance cohort study, the research team investigated the association between African American race and reclassification in a population where the potential for disparity in the conduct of surveillance has been minimized.

Graphical representation of Kaplan-Meier curve of reclassification-free survival by race.
Kaplan-Meier curve of reclassification-free survival by race. Image from Dr. Daniel Lin

Dr. Schenk described the study design: “A specific strength of the PASS cohort is the use of a standardized active surveillance protocol across all clinical sites.”  On PASS, prostate-specific antigen is measured every 3 months and ultrasound-guided prostate biopsies are conducted between 6 and 12 months after diagnosis, 24 months after diagnosis, then at 2 year-intervals thereafter. “The collection of PSA tests and surveillance biopsies at pre-specified, protocol-directed time-points in PASS provides a similar opportunity to detect reclassification among all men on PASS, thus minimizing the potential for ascertainment bias,” noted Dr. Schenk.

This analysis included 89 African American and 1,226 Caucasian American men who had a prostate cancer diagnosis within 5 years of enrollment in PASS, a Gleason Grade Group ≤ 2 cancer, and at least one surveillance biopsy after diagnostic biopsy. The median age of men in the study was 63 years, and the primary outcome was disease reclassification, defined as an increase in primary or secondary Gleason grade on subsequent biopsy. Overall, the study demonstrated no difference in reclassification-free survival between African American and Caucasian American men (see Figure). “The analyses showed that after accounting for diagnostic biopsy and clinical factors, African American men were at no higher risk of reclassification on subsequent prostate biopsies than Caucasian American men. In addition, African Americans who eventually underwent radical prostatectomy did not have a higher risk of adverse pathologic findings by delaying treatment,” summarized Dr. Schenk

“Our findings suggest that under a standardized protocol of regular PSA tests and prostate biopsies, active surveillance is an appropriate management strategy for African American men with early stage PCa. The potential for racial disparity in the intensity or conduct of surveillance has not been addressed by prior active surveillance studies, but in this study, we found no difference between African American and white patients in the frequency of PSA monitoring, biopsy compliance or the use of mp-MRI,” said Dr. Schenk. While this is the largest study to date, the authors note that the number of African Americans is still modest, and additional follow-up is needed. “We recently received funding for a U01 Infrastructure grant that will allow expansion of the population of African American patients in PASS.  With this support, we plan to expand upon the current study to include more African American men and longer follow-up time, which will also allow us to investigate longer-term outcomes such as recurrence or metastasis after treatment,” said Dr. Schenk.

This work was supported by the Canary Foundation, Department of Defense Prostate Cancer Research Program W81XWH1410595, Institute for Prostate Cancer Research

Fred Hutch/UW Cancer Consortium members Drs. Yingye Zheng, Peter S. Nelson, and Daniel W. Lin contributed to this research.

Schenk JM, Newcomb LF, Zheng Y, Faino AV, Zhu K, Nyame YA, Brooks JD, Carroll PR, Cooperberg MR, Dash A, Filson CP, Gleave ME, Liss M, Martin FM, Morgan TM, Nelson PS, Thompson IM, Wagner AA, Lin DW, African American race is not associated with risk of reclassification during active surveillance: Results from the Canary Prostate Cancer Active Surveillance Study (PASS), The Journal of Urology® (2018), doi: 10.1097/JU.0000000000000621.