Impact of dosimetric and clinical parameters on clinical side effects in cervix cancer patients treated with 3D pulse-dose-rate intracavitary brachytherapy

Abstract Background and purpose To assess the association between dosimetric/clinical parameters and gastrointestinal/urinary grade 2–4 side effects in cervix cancer patients treated with 3D pulse dose rate brachytherapy. Materials and methods Three hundred and fifty-two patients received brachytherapy associated with external-beam radiotherapy (EBRT) for 266 of them; 236 patients underwent surgery. The doses for the most exposed 2, and 0.1cm 3 ( D 2cc and D 0.1cc ) volumes of the rectum and bladder as well as bladder ICRU point dose ( D ICRU ) were converted into isoeffective doses in 2-Gy fractions. The clinical parameters analyzed were: age, smoking habits, arteritis, diabetes, previous pelvic surgery, FIGO stage, nodal status, pathology, pelvic surgery, EBRT and chemotherapy. Side effects were prospectively assessed using the CTCAEv3.0. Cutoff dose levels were defined separately for patients treated with EBRT and brachytherapy (Group 1) and with preoperative brachytherapy (Group 2). Results The median follow-up was 23.4months. In Group 1 a significant predictive value of rectum D 0.1cc and D 2cc , bladder D 0.1cc and D ICRU for gastrointestinal and urinary toxicity was found using as cutoff 83, 68, 109 and 68Gy α / β 3 . In Group 2 a significant predictive value of bladder D 0.1cc , D 2cc and D ICRU for urinary toxicity was found using as cutoff 141, 91 and 67Gy α / β 3 , but not for the rectum D 0.1cc and D 2cc ; smoking had a significant predictive value on urinary toxicity. Conclusions For patients treated with brachytherapy and EBRT, rectum D 0.1cc and D 2cc and bladder D 0.1cc and D ICRU had a predictive value for toxicity. For patients treated with preoperative brachytherapy, bladder D 0.1cc , D 2cc and D ICRU and smoking had a predictive value for urinary toxicity.