Combined Low Dose Rate Brachytherapy and External Beam Radiation Therapy for Intermediate-Risk Prostate Cancer.

Abstract

INTRODUCTION\nThis is a retrospective study conducted to report the tumor control and late toxicity outcomes of patients with intermediate-risk prostate cancer undergoing combination external beam radiation therapy and low dose rate brachytherapy (LDR-PB).\n\n\nMETHODS AND MATERIALS\nThirty-one patients received 45\xa0Gray (Gy) of external beam radiation therapy to the prostate and seminal vesicles, together with a brachytherapy boost via a transperineal prostate implant of I125 (108\xa0Gy). In addition, some patients received 6\xa0months of androgen deprivation therapy depending on physician preference. Biochemical failure was defined using the Phoenix consensus definition of the nadir PSA +2\xa0ng/mL. Toxicity was graded using the Common Terminology Criteria for Adverse Events version 4.0.\n\n\nRESULTS\nThe biochemical progression-free survival, metastases-free survival, and overall survival at 5\xa0years were 87.1%, 96.3%, and 92%, respectively. The incidence of late grade ≥1 and ≥2 genitourinary (GU) toxicities were 54.8% and 6.5%, respectively. The incidence of late grade 3 GU toxicity was 6.5% with urinary retention occurring in two patients requiring either a bladder neck incision or transurethral resection of the prostate. The incidence of late grade ≥1 and 2 gastrointestinal toxicities were 19.4% and 6.5%, respectively. No patients developed grade 3 gastrointestinal toxicity.\n\n\nCONCLUSION\nOur small series has shown a high biochemical progression-free survival consistent with the ASCENDE-RT and NRG Oncology/RTOG0232 LDR-PB boost arms. In addition, the risk of late grade 3 GU toxicity is far lower than that reported by the ASCENDE-RT study but comparable to other LDR-PB boost and LDR alone reports in the literature. Therefore, we are comfortable to continue offering LDR-PB boost to our patients with intermediate-risk prostate cancer.