Active Surveillance for Intermediate Risk Prostate Cancer: Survival Outcomes in the Sunnybrook Experience

To assess the applicability of active surveillance in patients with intermediate risk prostate cancer, we compared the survival outcomes of patients with low risk and intermediate risk disease.

Active surveillance was offered to all patients with low risk (cT1-T2b and Gleason score 6 and prostate specific antigen 10 ng/ml or less) and select intermediate risk disease (age greater than 70 years with cT2c or prostate specific antigen 15 ng/ml or less, or Gleason score 3+4 or less). Data from November 1995 to May 2013 were extracted from a prospectively collected database. The primary outcome was metastasis-free survival, and secondary outcomes were overall survival, cause specific survival and treatment-free survival.

A total of 213 intermediate risk and 732 low risk cases were identified. Median age was 72 years (IQR 67.3, 76.8) in the intermediate risk cohort and 67 years (IQR 60.6, 71.9) in the low risk group. Median followup was comparable (6.7 years for intermediate risk vs 6.5 years for low risk). Gleason 7 disease comprised 60% of the intermediate risk cohort. The 15-year metastasis-free, overall, cause specific and treatment-free survival rates were inferior in the intermediate risk group (metastasis-free survival HR 3.14, 95% CI 1.51-6.53, p=0.001, 82% for intermediate risk vs 95% for low risk). On further evaluation the estimated 15-year metastasis-free survival for cases of Gleason 6 or less with prostate specific antigen less than 10 ng/ml was 94%, Gleason 6 or less with prostate specific antigen 10 to 20 ng/ml was 94%, Gleason 3+4 with prostate specific antigen 20 ng/ml or less was 84% and Gleason 4+3 with prostate specific antigen 20 ng/ml or less was 63%.

These data support the use of active surveillance in low risk and intermediate risk cases of Gleason 6 but not Gleason 7 prostate cancer. Multiparametric magnetic resonance imaging and novel biomarkers might be vital in detecting favorable Gleason 7 disease.