Long-term disease-free survival and health-related quality of life results of high-dose-rate brachytherapy as monotherapy for low and intermediate-risk prostate cancer treated in a community cancer center.

Purpose: To determine the long-term disease-free survival, long-term toxicity, and effect on health-related quality of life of a two-fraction regimen of high-dose-rate (HDR) prostate brachytherapy.

Methods and materials: Patients with low- or intermediate-risk prostate cancer were treated with CT-planned HDR brachytherapy as monotherapy in two implants of 13.5 Gy in one community cancer center. Prostate-specific antigen (PSA), International Prostate Symptom Score (IPSS) and Expanded Prostate Index Composite (EPIC) questionnaires were evaluated at each follow-up visit. Biochemical recurrence (Phoenix definition) was evaluated to determine disease-free survival at 5 and 7 years. Proportion of patients in each IPSS category (mild = 0-7, moderate = 8-18, severe = 19+) was evaluated at each follow-up interval.

Results: Thirty patients were accrued to the study between 2014 and 2016. Median prostate-specific antigen was 8,7 (range 4.1-17.5). T stages were T1c = 65%, T2a = 21%, and T2b = 14%. Twenty-seven percent of patients had a Gleason score of 6 and 73% had a Gleason score of 7. 13% were in low risk category and 87% in intermediate risk category. Median follow-up was 84 months. There were no deaths at 84 months after brachytherapy. Disease-free survival was 90% at 5 years and 86% at 7 years. Two patients experienced late Grade 3 GU toxicity (6.6%).

Conclusions: This study serves as proof of concept that HDR monotherapy can be performed successfully with excellent long-term outcomes in a community cancer center with adequate training and experience. The long-term disease-free survival rate and the health-related quality of life seem acceptable as compared to other treatment modalities. Further study is ongoing with regard to the optimal dosing regimen for HDR monotherapy.