Dosimetry and Gastrointestinal Toxicity Relationships in a Phase II Trial of Pelvic Lymph Node Radiotherapy in Advanced Localised Prostate Cancer

摘要: Abstract Aims Pelvic lymph node (PLN) radiotherapy for high-risk prostate cancer is limited by late gastrointestinal toxicity. Application of rectal and bowel constraints may reduce risks side-effects. We evaluated associations between intensity-modulated (IMRT) dose-volume data long-term Materials methods Data from a single-centre dose-escalation trial PLN-IMRT were analysed, including conventionally fractionated (CFRT) hypofractionated (HFRT) schedules. Associations volumes rectum receiving specified doses clinician- patient-reported toxicity outcomes investigated independently. A metric, δ median (δM), was defined as the difference in medians volume groups with without at dose used to test statistically significant differences. Results Constraints respected most patients and, when exceeded, led higher rates Biologically relevant dose-points more numerous both mild moderate thresholds, but statistical significance after correction false discovery rate. Rectal V50Gy associated grade 2+ bleeding; V43Gy V47 (HFRT/4 days/week schedule) loose stools diarrhoea, respectively. Further investigation showed that CFRT bleeding had mean above treatment planning constraint. Conclusions When parameters are kept below tight constraints, low. Residual dosimetry loses much its predictive power setting cancer. have benchmarked safely delivering using or HFRT.