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.