Reduction of toxicity in brachytherapy using a new technique.

Abstract

PURPOSE\nThe purpose of the study was to elucidate the usefulness of a dose evaluation method for reducing late genitourinary (GU) toxicity in high-dose-rate brachytherapy (HDR-BT) of prostate cancer.\n\n\nMETHODS AND MATERIALS\nGU toxicity was scored in accordance with the Common Terminology Criteria for Adverse Events version 4.0. The prostatic urethra was divided into three segments (base\xa0=\xa0B, midgland\xa0=\xa0M, apex\xa0=\xa0A), which were subclassified into seven subgroups (B, M, A, BM, BA, MA, BMA) using a D10% color map of the urethra. Significance testing was conducted on urethral D0.1% and D10% among the seven subgroups. Grade < 2 GU toxicity was also implemented.\n\n\nRESULTS\nData of 174 patients with localized prostate cancer treated with HDR-BT combined with external beam radiotherapy between November 2011 and July 2014 were analyzed retrospectively. Median age was 74 (53-84) years, and median followup period was 44 (6-69) months. The number of Grade < 2 and Grade ≥ 2 toxicity was significantly different in the M subgroup than in the other subgroups (p\xa0<\xa00.05), suggesting increased radioresistance in the midgland urethra.\n\n\nCONCLUSIONS\nA high-dose-area evaluation method using a urethral D10% color map may be helpful in reducing late GU toxicity in HDR-BT for prostate cancer.