Factors influencing disease progression of prostate cancer under active surveillance: a McGill University Health Center cohort

Abstract

Objective: To evaluate the clinical and pathological factors influencing the risk of disease progression in a cohort of patients with low-intermediate risk prostate cancer under active surveillance (AS).

Patients and methods: We studied 300 patients diagnosed between 1992 and 2012 with prostate adenocarcinoma with favourable parameters or who refused treatment and were managed with AS. Of those, 155 patients with at least one repeat biopsy and no progression criteria at the time of the diagnosis were included for statistical analyses. Patients were followed every 3-6 months for prostate-specific antigen (PSA) measurement and physical examination. Patients were offered repeat prostatic biopsy every year. Disease progression was defined as the presence of one or more of the following criteria: ≥ 3 positive cores, >50% of cancer in at least one core, and a predominant Gleason pattern of 4.

Results: For the 155 patients, the mean (sd) age at diagnosis was 67(7) years; the median (interquartile range) follow-up was 5.4(3.6-9.5) years. Of these, 67, 25, six, and two patients had two, three, four, and five repeat biopsies, respectively. At baseline, 11 (7%) patients had a Gleason score of 3+4, while the remaining 144 (93%) patients had a Gleason score of ≤ 6. In all, 50 (32.3%) patients had disease progression on repeat biopsies, with a median progression-free survival time of 7 years. The rate of disease progression decreased after the second repeat biopsy. The 5-year overall survival rate was 100%. Having a PSA density (PSAD) of >0.15 ng/mL/mL, >1 positive core, and Gleason score >6 at the time of the diagnosis was associated with a significantly higher rate of disease progression on univariate analysis (P < 0.05), while a maximum percentage of cancer in any core of >10% showed a trend toward significance for a higher progression rate (P = 0.054). On multivariate analysis, only the presence of a PSAD of >0.15 ng/mL/mL remained significant for a higher progression rate (P < 0.05). Of the 155 patients, five (3.2%) subsequently received radiotherapy, 13 (8.4%) received hormonal therapy, and 13 (8.4%) underwent radical prostatectomy.

Conclusion: AS is a suitable management option for patients with clinically low-risk prostate cancer. A PSAD of >0.15 ng/mL/mL is an important predictor for disease progression.

Keywords: PSAD; active surveillance; adenocarcinoma; biopsy; prostate cancer; risk factor.