Comparison of genitourinary and gastrointestinal toxicity among four radiotherapy modalities for prostate cancer: Conventional radiotherapy, intensity-modulated radiotherapy, and permanent iodine-125 implantation with or without external beam radiotherapy
Menée sur 1 084 patients atteints d'un cancer de la prostate (durée médiane de suivi : 43 mois), cette étude compare les toxicités génito-urinaires et gastro-intestinales de quatre modalités de radiothérapie (conventionnelle, avec modulation d'intensité, curiethérapie seule ou en combinaison avec une radiothérapie externe)
Purpose : To compare late genitourinary (GU) and gastrointestinal (GI) toxicity following different prostate cancer treatment modalities. Materials and methods : This study included 1084 consecutive prostate cancer patients treated with conventional radiotherapy, intensity-modulated radiotherapy (IMRT), permanent iodine-125 implantation (PI) alone, and PI combined with external beam radiotherapy (PI + EBRT). The effects of treatment- and patient-related factors on late grade ⩾ 2 (G2+) GU/GI toxicity risk were assessed. Results : The median follow-up was 43 months (range, 12–97 months). Compared to the PI + EBRT, there was significantly less G2+ GU toxicity in the conventional radiotherapy (hazard ratio [HR] = 0.39; 95% CI, 0.20–0.77) and the IMRT (HR = 0.45, 95% CI, 0.27–0.73). Compared to the PI + EBRT, there was significantly more G2+ GI toxicity in the IMRT (HR = 2.38; 95% CI, 1.16–4.87). In PI-related groups, prostate equivalent dose in 2 Gy fractions was a significant predictor of G2+ GU toxicity (p = 0.001), and the rectal volume receiving more than 100% of the prescribed dose was a significant predictor of G2+ GI toxicity (p = 0.001). Conclusion : The differences in the late G2+ GU/GI risk cannot be explained by the differences in treatment modalities themselves, but by the total radiation dose to the GU/GI tract, which had a causal role in the development of late G2+ GU/GI toxicity across all treatment modality groups.