HIGH-DOSE-RATE AND LOW-DOSE-RATE BRACHYTHERAPY AS MONOTHERAPY FOR CLINICALLY LOCALIZED PROSTATE CANCER

Abstract

PURPOSE:To compare the outcome of high-dose-rate interstitial brachytherapy (HDR-BT) and low-dose-ratebrachytherapy (LDR-BT) as monotherapy for localized prostate cancer of low and intermediate risks progression.

METHODS AND MATERIALS: The study included 165 patients with localized prostate cancer in low and intermediate progression risk groups. We compared 65 patients treated with HDR-BT and 100 patients with LDR-BT as monotherapy. LDR-BT treated advanced disease with more hormonal therapy than HDR-BT. All patients were in low and intermediate risk groups for prostate cancer progression. HDR-BT as monotherapy was delivered in 2 fractions of 15 Gy, two weeks apart. LDR-BT was performed in a standard mode of 145 Gy. The median observation was 32 months. All patients gave written informed consent.

RESULTS: Overall biochemical free survival rate (BFSR) is 95,8%. There are 7 people having a growing prostatic specific antigen (PSA) while the case follow-up (in the group HDR-BT - 2 patients, LDR - 5 patients). Two recurrence cases with metastases in lymph nodes and bones were brought out as a result of ⁶⁸Ga-PSMA PET examination in the group of HDR-BT. In 4 cases out of 5 LDR-BT, a local recurrence was detected (p=0,085). All cases of relapse were found in patients at intermediate risk (p = 0,041). LDR-BT showed a higher incidence of genitourinary (GU) toxicity grade >2 than that of HDR-BT in the acute phase and grade 1 toxicity in late phase. Accumulated incidence of late grade >2 GU and GU toxicity was equivalent between HDR-BT and LDR-BT.

CONCLUSION: HDR-BT monotherapy showed an equivalent outcome to that of LDR-BT for low and intermediate risk patients. LDR-BT showed equivalent incidence of grade >2 late GU toxicities and higher grade >2 acute GU toxicity as that of HDR-BT as a monotherapy.