Comparison of Characteristics, Follow-up and Outcomes of Active Surveillance for Prostate Cancer According to Ethnicity in the GAP3 Global Consortium Database

Abstract

Background: Studies of active surveillance (AS) for prostate cancer (PCa) have focussed predominantly on Caucasian populations. Little is known about the experience of Asian men, while suitability for men of African descent has been questioned.

Objective: To compare baseline characteristics, follow-up, and outcomes for men on AS for PCa, according to ethnicity.

Design setting and participants: The study cohort included 13 centres from the GAP3 consortium that record ethnicity (categorised broadly as Caucasian/white, African/Afro-Caribbean/black, Asian, mixed/other, and unknown). Men with biopsy grade group >2, prostate-specific antigen (PSA) >20 ng/ml, T stage ≥cT3, or age >80 yr were excluded.

Outcome measurements and statistical analysis: Clinical characteristics, follow-up schedules, outcome status, and reasons for discontinuation were compared across ethnic groups. Risk of upgrading, potential disease progression (grade group ≥3 or T stage ≥3), suspicious indications (any upgrading, number of positive cores >3, T stage ≥cT3, PSA >20 ng/ml, or PSA density >0.2 ng/ml/cc2), and conversion to treatment were assessed using mixed-effect regression models.

Results and limitations: The eligible cohort (n = 9158) comprised 83% Caucasian men, 6% men of African descent, 5% Asian men, 2% men of mixed/other ethnicity, and 4% men of unknown ethnicity. Risks of suspicious indicators (hazard ratio = 1.27; 95% confidence interval [CI] 1.12-1.45), upgrading (odds ratio [OR] = 1.40; 95% CI 1.14-1.71), and potential progression (OR = 1.46; 95% CI 1.06-2.01) were higher among African/black than among Caucasian/white men. Risk of transitioning to treatment did not differ by ethnicity. More Asian than Caucasian men converted without progression (42% vs 26%, p < 0.001). Heterogeneity in surveillance protocols and racial makeup limit interpretation.

Conclusions: This multinational study found differences in the risk of disease progression and transitioning to treatment without signs of progression between ethnic groups. Further research is required to determine whether differences are due to biology, sociocultural factors, and/or clinical practice.

Patient summary: This international study compared prostate cancer active surveillance outcomes by ethnicity. Risks of upgrading and disease progression were higher among African than among Caucasian men. Transitioning to treatment without progression was highest among Asian men. Understanding of these differences requires further investigation.