Dose-volume constraints for severe acute gastrointestinal toxicity in cervical cancer patients receiving extended-field intensity-modulated radiotherapy and concurrent chemotherapy.

Abstract

Extended-field intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy may lead to severe toxicity. This study aims to investigate the incidence and dosimetric predictors of acute gastrointestinal toxicity in cervical cancer patients. Dosimetric data of the duodenum and small bowel loop from 273 eligible patients were analyzed. Logistic regression and Pearson's pairwise correlation were used to identify the best predictors. Receiver operating characteristic curves were used to determine the optimal cutoff values. Logistic models were established to predict the normal tissue complication probability. Twenty-six patients experienced grades ≥ 3 (G3⁺) vomiting, while seven experienced G3⁺ diarrhea. Either the duodenal volume receiving ≥ 29 Gy (V₂₉; p = 0.002) or V₄₉ (p = 0.014) could predict the incidence of G3⁺ vomiting. The incidence was 1.3 % vs. 12.8 % in patients with V₂₉ ≤ 43.5 % vs. > 43.5 % (p = 0.008). For patients with V₄₉ ≤ 9.2 % vs. > 9.2 %, the incidence was 7.6 % vs. 16.1 % (p = 0.077). The plans for 22 patients had to be modified due to vomiting. It was found that duodenal V₂₉ (p = 0.012) was a predictor for replanning, with an incidence of 3.3 % vs. 17.6 % in patients with V₂₉ ≤ 51.3 % vs. > 51.3 % (p < 0.001). The V₂₂ of the small bowel was selected to predict the incidence of G3⁺ diarrhea, which were 0.6 % and 5.6 % in patients with V₂₂ ≤ 62.3 % and > 62.3 %, respectively (p = 0.031). Limiting V₂₉ and V₄₉ of the duodenum, as well as V₂₂ of the small bowel loop, may help reduce the risk of acute G3⁺ gastrointestinal toxicity when treating cervical cancer with extended-field concurrent IMRT.