Hip toxicity after prostate RTHip-related toxicity after prostate radiotherapy: Treatment related or coincidental?

Background and purposeTo evaluate the incidence and predictors of hip toxicity postradiotherapy for localized prostate cancer.Methods and materials4067 prostate cancer patients were treated with external beam radiotherapy (EBRT; n = 2569; 63%) or brachytherapy with or without supplemental EBRT (n = 1508; 27%). 43% (n = 1738) were treated with neo-adjuvant and concurrent ADT and 57% (n = 2329) with radiotherapy alone. Hip toxicity was defined as moderate or severe pain upon ambulation with or without the need for hip-revision surgery. Median follow-up was 7 years (range, 3-21 years).ResultsOne hundred twenty-one (2.7%) patients developed moderate-to-severe hip pain after radiotherapy affecting ambulation. Of these, 73 (60%) required hip replacement secondary to persistent hip pain. Among patients with baseline degenerative joint disease (DJD) changes on scans, 10-year incidence of hip-related toxicity was 11% versus 3% for those without such changes (P < .001). The only variables on multivariate analysis associated with hip-related toxicity post-radiotherapy were baseline DJD on imaging (P < .0001) and prolonged ADT for salvage therapy (P < .0001).ConclusionsProstate EBRT or brachytherapy is associated with low incidence of long-term hip-related toxicity. The only variables identified associated with hip toxicity posttherapy was the presence of baseline DJD and prolonged salvage ADT posttreatment for patients developing recurrence.