Patient-reported urinary incontinence after radiotherapy for prostate cancer: Quantifying the dose–effect

Publication date: Available online 18 August 2017
Source:Radiotherapy and Oncology
Author(s): Cesare Cozzarini, Tiziana Rancati, Federica Palorini, Barbara Avuzzi, Elisabetta Garibaldi, Damiano Balestrini, Domenico Cante, Fernando Munoz, Pierfrancesco Franco, Giuseppe Girelli, Carla Sini, Vittorio Vavassori, Riccardo Valdagni, Claudio Fiorino
Background and purposeUrinary incontinence following radiotherapy (RT) for prostate cancer (PCa) has a relevant impact on patient's quality of life. The aim of the study was to assess the unknown dose–effect relationship for late patient-reported urinary incontinence (LPRUI).Methods and materialsPatients were enrolled within the multi-centric study DUE01. Clinical and dosimetry data including the prescribed 2Gy equivalent dose (EQD2) were prospectively collected. LPRUI was evaluated through the ICIQ-SF questionnaire filled in by the patients at RT start/end and therefore every 6months. Patients were treated with conventional (74–80Gy, 1.8–2Gy/fr) or moderately hypo-fractionated RT (65–75.2Gy, 2.2–2.7Gy/fr) in 5 fractions/week with intensity-modulated radiotherapy. Six different end-points of 3-year LPRUI, including or not patient's perception (respectively, subjective and objective end-points), were considered. Multivariable logistic models were developed for each end-point.ResultsData of 298 patients were analyzed. The incidence of the most severe end-point (ICIQ-SF>12) was 5.1%. EQD2 calculated with alpha–beta=0.8Gy showed the best performance in fitting data: the risk of LPRUI markedly increased for EQD2>80Gy. Previous abdominal/pelvic surgery and previous TURP were the clinical factors more significantly predictive of LPRUI. Models showed excellent performances in terms of goodness-of-fit and calibration, confirmed by bootstrap-based internal validation. When included in the analyses, baseline symptoms were a major predictor for 5 out of six end-points.ConclusionsLPRUI after RT for PCa dramatically depends on EQD2 and few clinical factors. Results are consistent with a larger than expected impact of moderate hypo-fractionation on the risk of LPRUI. As expected, baseline symptoms, as captured by ICIQ-SF, are associated to an increased risk of LPRUI.



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