Prostate-specific Antigen Levels Following Brachytherapy Impact Late Biochemical Recurrence in Japanese Patients With Localized Prostate Cancer

Abstract

Background/aim: Evaluation of long-term outcomes is essential for the successful treatment of localized prostate cancer; however, the risk of late recurrence following brachytherapy is still not clear. This study aimed to evaluate the long-term outcomes of low-dose-rate brachytherapy (LDR-BT) for localized prostate cancer in Japanese patients and identify factors associated with late recurrence after treatment.

Patients and methods: This single-center, cohort study included patients who underwent LDR-BT at the Tokushima University Hospital in Japan between July 2004 and January 2015; 418 patients, who were followed-up at least 7 years after LDR-BT, were included in the study. Biochemical progression free survival (bPFS) was defined according to the Phoenix definition (nadir PSA+2 ng/ml) and bPFS and cancer specific survival (CSS) were calculated using Kaplan-Meier survival curves. Univariate and multivariate analyses were performed using Cox proportional hazard regression models.

Results: Approximately half of the patients with PSA >0.5 ng/ml at 5 years after LDR-BT had a recurrence within the next 2 years. However, only 1.4% of the patients with a PSA ≤0.2 ng/ml at 5 years post-treatment showed tumor recurrence, including those at high risk of treatment failure according to the D'Amico classification. In multivariate analysis, PSA level at 5 years post-treatment was the only predictor of late recurrence after 7 years of treatment.

Conclusion: PSA levels at 5 years post-treatment were associated with long-term recurrence of localized prostate cancer, which can help alleviate patient anxiety concerning prostate cancer recurrence if PSA levels remain low at 5 years after LDR-BT.

Keywords: Prostate cancer; brachytherapy; long-term outcomes.