Evaluating Risk Factors Associating With Late Recurrence After Low-Dose-Rate Brachytherapy for Prostate Cancer Using...

Area of Science:

• Oncology
• Radiotherapy
• Biostatistics

Background:

• The Phoenix definition is standard for biochemical recurrence (BCR) after prostate cancer radiation, but a clear definition of cure is lacking.
• Late BCR, defined as occurring ≥5 years post-treatment, requires further investigation for patients treated with low-dose-rate brachytherapy (LDR-BT).

Purpose of the Study:

• To identify predictors of late BCR (≥5 years) in prostate cancer patients treated with LDR-BT who were recurrence-free at 5 years.
• To utilize machine-learning methods to analyze factors associated with late BCR after LDR-BT.

Main Methods:

• Retrospective analysis of 1419 patients undergoing LDR-BT (2004-2019).
• Focus on 1123 patients recurrence-free at 5 years to analyze late BCR.
• Application of Random Survival Forest (RSF) and survival decision-tree analyses to identify predictive factors.

Main Results:

• The 10-year BCR-free survival rate was 94.8%.
• Key predictors for late BCR identified by RSF include 5-year PSA value, 5-year PSA doubling time (PSA-DT), primary Gleason pattern, and NCCN risk classification.
• Lower PSA levels (≤0.93 ng/mL) and longer PSA-DT (≥5.3 years) at 5 years significantly correlated with higher 10-year recurrence-free rates.

Conclusions:

• Prostate-specific antigen (PSA) level and PSA doubling time (PSA-DT) at 5 years post-LDR-BT are robust predictors of late BCR.
• Findings suggest potential for safely extending follow-up intervals for low-risk prostate cancer patients, reducing healthcare costs and patient burden.