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

• Published in: Radiotherapy and oncology Vol. 125; no. 1; pp. 101 - 106
• Main Authors: Cozzarini, Cesare, Rancati, Tiziana, Palorini, Federica, Avuzzi, Barbara, Garibaldi, Elisabetta, Balestrini, Damiano, Cante, Domenico, Munoz, Fernando, Franco, Pierfrancesco, Girelli, Giuseppe, Sini, Carla, Vavassori, Vittorio, Valdagni, Riccardo, Fiorino, Claudio
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.10.2017
• Subjects: Aged; Dose Fractionation; Dose-Response Relationship, Radiation; Humans; Incontinence; Male; Middle Aged; Predictive models; Prostate cancer; Prostatic Neoplasms - radiotherapy; Quality of Life; Radiation Injuries - etiology; Radiotherapy; Radiotherapy, Intensity-Modulated - adverse effects; Risk Factors; Self Report; Surveys and Questionnaires; Urinary Incontinence - etiology; Predictive models; Incontinence; Radiotherapy; Prostate cancer
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2017.07.029

Urinary 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). Patients 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. Data 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. LPRUI 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.