Comparison of Pathological and Oncologic Outcomes of Favorable Risk Gleason Score 3 + 4 and Low Risk Gleason Score 6 Prostate Cancer: Considerations for Active Surveillance

Abstract

Purpose: Recent NCCN^® (National Comprehensive Cancer Network®) Guidelines® show that patients with biopsy Gleason score 3 + 4/Grade Group 2 but otherwise favorable features are active surveillance candidates. However, little is known about the long-term outcomes compared to that in men in the low risk Gleason score 6/Grade Group 1 group. We sought to clarify the risk of adverse features and oncologic outcomes in surgically treated, favorable Grade Group 2 vs 1 cases.

Materials and methods: We queried our prospectively maintained radical prostatectomy database for all 8,095 patients with biopsy Grade Group 1 or 2 prostate cancer who otherwise fulfilled the NCCN low risk definition of prostate specific antigen less than 10 ng/ml and cT2a or less, and who underwent radical prostatectomy from 1987 to 2014. Multivariable logistic regression and Kaplan-Meier methods were used to compare pathological and oncologic outcomes.

Results: Organ confined disease was present in 93.9% and 82.6% of Grade Group 1 and favorable intermediate risk Grade Group 2 cases while seminal vesicle invasion was noted in 1.7% and 4.7%, and nodal disease was noted in 0.3% and 1.8%, respectively (all p <0.0001). On multivariable logistic regression biopsy proven Grade Group 2 disease was associated with a threefold greater risk of nonorgan confined disease (OR 3.1, 95% CI 1.7-5.7, p <0.001). The incidence of late treatment (more than 90 days from surgery) in Grade Group 1 vs 2 was 3.1% vs 8.5% for hormonal therapy and 6.0% vs 12.2% for radiation (p <0.001). In the Grade Group 1 vs 2 cohorts the 10-year biochemical recurrence-free survival rate was 88.9% vs 81.2% and the 10-year systemic progression-free survival rate was 99% vs 96.5% (each p <0.001).

Conclusions: Men at favorable risk with Grade Group 2 disease who are considering active surveillance should be informed of the risks of harboring adverse pathological features which impact secondary therapies and an increased risk of cancer progression.

Keywords: neoplasm grading; prostatectomy; prostatic neoplasms; risk factors; watchful waiting.