Patient Reported Outcomes (PRO) in Those Receiving a High Dose Rate (HDR) Brachytherapy Prostate Boost Compared to Intensity Modulated Radiotherapy (IMRT) Alone

Abstract

Prospective data show improved biochemical control-at a cost of worse urinary and overall physical function scores-in patients receiving a low dose rate (LDR) prostate brachytherapy boost when compared to IMRT alone. An HDR prostate boost may cause less toxicity than LDR brachytherapy. We, therefore, compared patient status post an HDR prostate boost or IMRT alone to see if there were any differences in PRO data between groups.American Urologic Association (AUA) symptom score and Sexual Health Inventory for Men (SHIM) score were prospectively collected for men with intermediate/high risk prostate cancer at a single institution. Genitourinary (GU) and gastrointestinal (GI) toxicity were also obtained and graded using the Common Terminology Criteria for Adverse Events v3.0 (CTCAE). Patients had undergone either IMRT plus an HDR prostate boost (n = 53) or IMRT alone (n = 346). Patients were excluded if they had prior TURP, a history of irritable bowel disease (IBD), or a prostate size greater than 75 cc. PRO were compared at baseline and at 1-2 years. AUA and SHIM scores were compared using a two-sample Wilcoxon rank-sum test.We identified 346 patients treated between 2001 and 2018 with IMRT alone (80 Gy median EBRT dose) and 53 patients treated with HDR boost (46 Gy median EBRT dose). Patient characteristics and unadjusted PRO scores are reported below in the table. There was no grade 4 or 5 acute or late GU or GI events.Zero grade 3 late GI events occurred in the IMRT plus HDR group, while 1.7% of patients (n = 6) in the IMRT alone group experienced late grade 3 GI toxicity; this difference was not statistically significant. Patients receiving an HDR boost have greater change in AUA score at 1-2 years compared to the IMRT alone patients; this change does not appear clinically significant. SHIM scores are higher in the HDR group before and after treatment, suggesting patients selected for a prostate boost may have better erectile function at baseline. Lastly, clinicians seem more comfortable withholding ADT in patients receiving an HDR prostate boost, possibly due to the higher ablative dose provided by HDR brachytherapy.