The present study aims to identify predictive factors for urinary toxicity and self-reported symptoms after external beam radiotherapy (EBRT) for prostate cancer.

Two-hundred and eighty patients treated with EBRT for prostate cancer were included in the present study. Toxicity was scored following the grading system based on Radiation Therapy Oncology Group (RTOG) scale. International Prostatic Symptom Score (IPSS) and Consultation on Incontinence Questionnaires – Short Form (ICIQ-SF) were used to analyse self-reported symptoms. Acute and late urinary toxicities were correlated to clinical and treatment parameters, radiation dosimetry data, IPSS and ICIQ-SF.

Median patient age was 74 years (range, 64–83). Thirty-one percent experienced acute G1 urinary toxicity, 24% G2 and 3% G3. Fourteen percent experienced G1 late urinary toxicity and 3% G2. Bladder volume<200 cc was associated with acute urinary toxicity (P=0.014); use of MRI for treatment planning allowed a lower incidence of late toxicity (P=0.062) and use of IMRT allowed for reduced incidence in late toxicity (P=0.038). Maximum bladder dose correlated with late urinary toxicity (P=0.014). The analysis of self-reported symptoms showed a significant correlation between IPSS baseline values (P=0.009), presence of nocturia (P=0.002), bladder urgency (P=0.024) and incontinence (P=0.024) and development of acute urinary toxicity at univariate analysis. At multivariate logistic regression analysis, bladder filling, IPSS value, nocturia, and urinary incontinence retained significant correlation with acute toxicity (P=0.0003).

Significant independent predictors for acute urinary toxicity grade≥2 were bladder filling, IPSS value, nocturia, and urinary incontinence at baseline assessment.