Conditional survival of patients with low-risk prostate cancer: Temporal changes in active surveillance permanence over time.

PURPOSE: To determine risk categories for patients with prostate cancer (PCa) in active surveillance (AS) and to test the conditional survival (CS) that examined the effect of event-free survival since AS-entrance.

MATERIALS AND METHODS: From January 2012 to December 2020 we analyzed 606 patients with PCa enrolled in our AS program. Kaplan-Meier (KM) plots depicted AS-exit rate. Multivariable Cox regression models (MCRMs) tested for AS-exit rate independent predictors to determine risk categories. CS estimates were used to calculate overall AS-exit rate after event-free survival intervals of 1, 2, 3, and 5 years, and after stratification according to risk categories.

RESULTS: At MCRMs PSAd ≥ 0.15 (HR: 1.43; P-value 0.04), PI-RADS 4-5 (HR: 2.56; P-value <0.001) and number of biopsy positive cores ≥ 2 (HR: 1.75; P-value <0.001) were independent predictors of AS-exit. These variables were used to determine risk categories: low-, intermediate- and high-risk. Overall, according to CS-analyses, 5-year AS-exit free rate increased from 59.7% at baseline, to 67.3%, 74.7%, and 89.4% in patients who remained in AS respectively ≥1, ≥2, ≥3 and ≥5 years. After stratification according to risk categories, in those patients who remained in AS ≥ 5 years, 5-year AS-exit free rates increased from 76.3% to 100% in patients with a low-risk, from 62.7% to 83.7% in patients with an intermediate-risk and from 42.3% to 87.5% in patients with a high-risk.

CONCLUSIONS: CS models showed a direct relationship between event-free survival duration and subsequent AS permanence in overall PCa patients and after stratification according to risk categories.