Radiation-Induced Pelvic Colorectal Obstruction After Neoadjuvant Chemoradiotherapy and Sphincter-Saving Surgery for Rectal Cancer: Is IMRT Better?

Abstract PurposeRadiation-induced pelvic colorectal obstruction (RIPCO) is a severe complication after neoadjuvant chemoradiotherapy (NCRT) and sphincter-saving surgery (SPS) with for rectal cancer. The incidence and risk factors remain unclear. This study aimed to evaluate the influences of anatomical and clinical parameters including radiation modalities on this complication.MethodsFrom 2010 to 2018, data from patients who received NCRT and SPS with a diverting stoma for rectal cancer were collected. Patients with clinical parameters and complete pelvimetric parameters associated with RIPCO were included for univariate and multivariate analyses. Receiver operating characteristic curves were used to calculate the best cutoff value.ResultsA total of 726 patients with rectal carcinoma received NCRT and SPS with diverting stoma, and 157 patients had complete pelvimetric data. Eighteen of the 726 (2.5%) patients developed RIPCO. Eleven patients only received recreation of a diverting stoma, and four were cured by intersphincteric resection with reconstruction of anastomosis and diverting stoma. In multivariate analysis, BMI (P =0.001), sacral depth (P=0.046), and Intensity-modulated radiotherapy (IMRT) (P<0.001) were independent predictors. The cutoff values of BMI and sacral depth were 21.1 kg/m2 and 4.1 cm, respectively. IMRT was independently associated with a lower incidence of RIPCO (P<0.001). The four-factor scoring system showed that the sensitivity was 88.9%, and the specificity was 85.6%. The AUC was 0.921.ConclusionRIPCO is a rare but severe complication after SPS following NCRT. A BMI more than 21.1 kg/m2, a sacral depth less than 4.1 cm, and IMRT may decrease the risk of RIPCO.