Dose-volume relationships between enteritis and irradiated bowel volumes during 5-fluorouracil and oxaliplatin based chemoradiotherapy in locally advanced rectal cancer.

Purpose. Radiation enteritis is the main acute side-effect during pelvic irradiation. The aim of this study was to quantify the dose-volume relationship between irradiated bowel volumes and acute enteritis during combined chemoradiotherapy for rectal cancer.Material and methods. Twenty-eight patients with locally advanced rectal cancer received chemoradiotherapy. The radiation therapy was given with a traditional multi-field technique to a total dose of 50 Gy, with concurrent 5-Fluorouracil (5-FU) and oxaliplatin (OXA) based chemotherapy. All patients underwent three-dimensional CT-based treatment planning. Individual loops of small and large bowel as well as a volume defined as “whole abdomen” were systematically contoured on each CT slice, and dose-volume histograms were generated. Diarrhea during treatment was scored retrospectively according to the NCI Common Toxicity Criteria scale.Results. There was a strong correlation between the occurrence of grade 2+diarrhea and irradiated small bowel volume, mo...