Characterization of a "low-risk" cohort of grade group 2 prostate cancer patients: Results from the Shared Equal Access Regional Cancer Hospital database.

Abstract

To examine if there is a subset of men with grade group 2 prostate cancer who could be potential candidates for active surveillance. We used the Shared Equal Access Regional Cancer Hospital database to identify 776 men undergoing radical prostatectomy from 2006 to 2015 with >8 biopsy cores obtained and complete information. We compared men who fulfilled low-risk disease criteria (clinical stage T1c/T2a; grade group 1; prostate-specific antigen ≤10 ng/mL) with the exception of grade group 2 versus men who met all three low-risk criteria. Logistic regression was used to test the association between grade group and radical prostatectomy pathological features. Biochemical recurrence was examined using Cox models. To examine whether there was a subset of men with low-volume grade group 2 with comparable outcomes to low-risk men, we repeated all analyses limiting the percentage of positive cores in the grade group 2 group to ≤33%, and positive cores to ≤4, ≤3 or ≤2. Grade group 2 low-risk men had increased risk of pathological grade group 3 or higher (P < 0.001), extraprostatic extension (P < 0.001), seminal vesicle invasion (P < 0.001) and higher risk of biochemical recurrence (hazard ratio = 1.76, P = 0.006). Using increasingly strict definitions of low-volume disease, at ≤2 positive cores there was no difference in adverse pathology between groups (all P > 0.2), except higher pathological grade group (P = 0.006). Biochemical recurrence was similar in men in grade group 1 and grade group 2 (hazard ratio = 1.24; P = 0.529). Among men with prostate-specific antigen ≤10 ng/mL and clinical stage T1c/T2a, those in grade group 2 with ≤2 total positive cores have similar rates of adverse pathology and biochemical recurrence as men with grade group 1.