High-dose-rate brachytherapy as monotherapy for localized prostate cancer using three different doses - 14 years of single-centre experience.

Purpose To evaluate clinical outcomes in patients with localized prostate cancer (LPC) treated with 3D conformal high-dose-rate (HDR) brachytherapy (BT) as monotherapy. Material and methods From March 2004 to November 2017, 277 men with LPC underwent 3D conformal HDR-BT as monotherapy, with a temporary implant. The dose prescription was: 38 Gy in 4 fractions (149 patients), 27 Gy in 2 fractions (41 patients), and 19-20 Gy in a single fraction (87 patients). Biochemical progression-free survival (bPFS), progression-free survival (PFS), and cancer-specific survival (CSS) were calculated. Acute and late genitourinary (GU) and gastrointestinal (GI) toxicity assessment were performed using Common Terminology Criteria for Adverse Events v5.0. Results The mean age was 67 (range, 47-81) years. Overall, 145 patients were low-risk, 116 intermediate-risk, and 16 high-risk prostate cancer. After a median follow-up of six years (range, 6-160 months), bPFS, PFS, and CSS were 81%, 96%, and 97%, respectively. Dose prescription, initial prostate specific antigen (iPSA) ≥ 9,5 ng/ml, and high-risk disease resulted in prognostic factors regarding bPFS. Only G2-G3 acute or late GI and GU toxicities were observed. Conclusions HDR-BT as monotherapy is a valid and safe treatment modality for localized prostate cancer. After a long follow-up, patients receiving 19-20 Gy in a single fraction had a lower biochemical control rate compared to patients receiving 38 Gy in 4 fractions or 27 Gy in 2 fractions. Randomized prospective trials with a longer follow-up are necessary to confirm our results, and define total doses and dose per fraction for HDR-BT in patients with LPC.