Timing of High-Dose-Rate Brachytherapy With External Beam Radiation Therapy in Patients With Intermediate- and High-Risk Localized Prostate Cancer and Its Effects on Toxicity and Quality of Life: A Randomized Controlled Trial (THEPCA)

Abstract

BackgroundHDR brachytherapy(HDR-BT) and external beam radiotherapy(EBRT) are effective treatments for prostate cancer(PC) but cause genitourinary(GU) and gastrointestinal(GI) toxicities. There is no consensus on the timing of HDR-BT in relation to EBRT and the effect of sequencing on patients. ObjectiveThe primary objective was to assess differences, if any, in the incidence of Grade 3 or higher GU toxicities from treatment. We also aimed to explore the incidence of G1-4 GI toxicities, quality of life and patient satisfaction. Suppression of PSA and signals for survival differences were also analysed. MethodologyA single-centre randomised trial in intermediate and high-risk localised PC patients to receive HDR-BT before (Arm A) or after (Arm B) EBRT. Toxicities were graded using CTCAE. IIEF and FACT-P were used to assess erectile dysfunction and QOL at 0, 3, 9 and 12 months. Results50 patients were recruited to each arm, with 48 and 46 patients completing treatment and follow up in each arm. 81.5% had high-risk disease. There were no G3 or G4 GU or GI toxicities. G1 urinary frequency was the most common adverse event experienced in both arms, peaking in incidence 3 months after commencing treatment (45.7 and 42.2% in Arm A and B, respectively). Up to 11 % of patients reported G1 urinary frequency at 12 months. Other G1 GU toxicities experienced by >10% of patients were urinary tract obstruction, tract pain and urgency. These symptoms also peaked in incidence at 3 months. G2 GU toxicities were uncommon and experienced in a maximum of 2 patients within each arm at any time point.Over 30% of patients had G1 flatulence at baseline and this remained the most frequently occurring G1 GI toxicity throughout the study, peaking at 12months (21.4% and 25.6% in Arm A and Arm B, respectively). Other GI toxicities experienced by more than 10% of patients were GI pain, proctitis and rectal mucositis, most of which demonstrated a peak incidence at 3 or 9 months. G2 GI toxicities were uncommon, except G2 flatulence.No significant difference was found in CTCAE, IPSS, IIEF, FACT-P and QOL scores between the arms.Median PSA follow-up was 5 years. 7 patients had treatment failure in each arm. DFRS was 93.3% and 90.7% at 5 years in Arm A and B respectively, with median failure time of 60 and 48 months in Arm A and B respectively. There were no statistically significant difference between arms. ConclusionsThe sequencing of HDR-BT and EBRT did not impact the incidence of G3 or G4 toxicities and no significant differences were seen in other patient reported outcomes. Treatment was well tolerated with maintained QOL scores. Treatment failure was low in both arms in a high-risk cohort, however a larger study with longer follow up is underway to establish whether the difference in median time to failure between the two arms is a signal of superiority.