A randomised phase-III trial compared external beam radiotherapy (EBRT) alone with EBRT combined with high-dose-rate brachytherapy boost (HDR-BTb) in localised prostate adenocarcinoma. Previous analysis, at median follow up of 85 months, demonstrated improved relapse free survival (RFS) with EBRT+HDR-BTb. This data has now been updated with a median follow up of 131 months.
From December 1997 to August 2005, patients were assigned either to EBRT alone delivering 55 Gy in 20 fractions over 4 weeks or EBRT followed by a temporary high-dose-rate implant delivering 2 x 8·5 Gy over 24h. The primary endpoint was RFS defined by a PSA rise ≥ 2.0µg/l above nadir, clinical progression or death. Actuarial survival rates and Hazard Ratios (HRs) were calculated using the Kaplan-Meier method and Cox's Proportional Hazard Model, respectively. Secondary endpoints were overall survival (OS), urinary and bowel toxicity.
106 patients received EBRT alone and 110 EBRT+HDR-BTb. Median time to relapse was 137 months in the HDR-BTb arm compared to 82 months for EBRT alone (p = 0·01). A 29% risk of recurrence with EBRT alone was observed (p = 0·001), resulting in a 21% improvement in RFS at 12 years with EBRT + HDR-BTb. In multivariate analysis treatment arm, risk category and no androgen deprivation therapy were significant covariates for risk of relapse. Differences in overall survival were not significant.
At 12 years there remains a significant improvement in RFS after EBRT + HDR-BTb; both treatments were equitoxic for severe late urinary and bowel events and urethral strictures.
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 2020 Oct 01 [Epub ahead of print]
Peter J Hoskin, Ana M Rojas, Peter J Ostler, Linda Bryant, Gerry J Lowe
Cancer Centre, Mount Vernon Hospital, Northwood, Middlesex, UK; University of Manchester, Manchester, UK. Electronic address: ., Cancer Centre, Mount Vernon Hospital, Northwood, Middlesex, UK.