Evaluating the Outcomes of Active Surveillance in Grade Group 2 Prostate Cancer: Prospective Results From the Canary PASS Cohort.

INTRODUCTION Active Surveillance (AS) for grade group 2 (GG2) patients is not yet well-defined. We sought to compare clinical outcomes of men with GG1 and GG2 prostate cancer undergoing AS in a large prospective North American cohort. METHODS Participants were prospectively enrolled in an AS study with protocol-directed follow up at 10 centers in the US and Canada. We evaluated time from diagnosis to biopsy grade reclassification and time to treatment. In men treated after initial surveillance, adverse pathology (AP) and recurrence were also analyzed. RESULTS At diagnosis, 154 (9%) had GG2 and 1574 (91%) had GG1. Five-year reclassification rates were similar between GG2 or GG1 (30% vs 37%, p=0.11). However, more patients with GG2 were treated at 5 years (58% vs 34%, p <0.001) and GG at diagnosis was associated with time to treatment (HR=1.41; p=0.01). Treatment rates were similar in patients who reclassified during AS, but in patients who did not reclassify, those diagnosed with GG2 underwent definitive treatment more often than GG1 (5-year treatment rates 52% and 12%, p <0.0001). In participants who underwent RP after initial surveillance, the adjusted risk of AP was similar (HR=1.26; p=0.4). Biochemical recurrence (BCR) within 3 years of treatment for GG2 and GG1 patients was 6% for both groups. CONCLUSIONS In patients on active surveillance, the rate of definitive treatment is higher after an initial diagnosis of GG2 than GG1. Adverse pathology after RP and short-term BCR after definitive treatment were similar between GG2 and GG1.