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

Objectives: To examine if there is a subset of men with grade group 2 prostate cancer who could be potential candidates for active surveillance.

Methods: 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.

Results: 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).

Conclusions: 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.