Development and Validation of a Post-Radiotherapy Prediction Model for Bowel Dysfunction After Rectal Cancer Resection.

BACKGROUND & AIMS: The benefit of radiotherapy for rectal cancer is based largely on a balance between a decrease in local recurrence and an increase in bowel dysfunction. Predicting postoperative disability is helpful for recovery plans and early intervention. We aimed to develop and validate a risk model to improve the prediction of major bowel dysfunction after restorative rectal cancer resection with neoadjuvant radiotherapy using perioperative features. METHODS: Eligible patients more than 1 year after restorative resection following radiotherapy were invited to complete the low anterior resection syndrome (LARS) score at 3 national hospitals in China. Clinical characteristics and imaging parameters were assessed with machine learning algorithms. The post-radiotherapy LARS prediction model (PORTLARS) was constructed by means of logistic regression on the basis of key factors with proportional weighs. The accuracy of the model for major LARS prediction was internally and externally validated. RESULTS: A total of 868 patients reported a mean LARS score of 28.4 after an average time of 4.7 years since surgery. Key predictors for major LARS included the length of distal rectum, anastomotic leakage, proximal colon of neorectum, and pathologic nodal stage. PORTLARS had a favorable area under the curve for predicting major LARS in the internal dataset (0.835; 95% CI, 0.800-0.870, n = 521) and external dataset (0.884; 95% CI, 0.848-0.921, n = 347). The model achieved both sensitivity and specificity >0.83 in the external validation. In addition, PORTLARS outperformed the preoperative LARS score for prediction of major events. CONCLUSIONS: PORTLARS could predict major bowel dysfunction after rectal cancer resection following radiotherapy with high accuracy and robustness. It may serve as a useful tool to identify patients who need additional support for long-term dysfunction in the early stage. CLINICALTRIALS: gov, number NCT05129215.

Risk Factors of Delayed Recovery of Gastrointestinal Function After Ileostomy Reversal for Rectal Cancer Patients.

PURPOSE: The aim of this study was to identify the risk factors associated with delayed recovery of gastrointestinal function after ileostomy reversal for rectal cancer patients. METHODS: In this retrospective study, the data of rectal cancer patients who underwent ileostomy reversal from January 2018 to December 2019 at the Sixth Affiliated Hospital of Sun Yat-sen University were assessed to investigate potential risk factors of delayed flatus after ileostomy reversal. RESULTS: A total of 282 patients were eligible for this study. Postoperative first flatus time ranged from 1 to 9 days, of which 58.8% patients presented with delayed flatus that was longer than 3 days. Univariate analysis showed that delayed postoperative flatus was significantly associated with the length of postoperative hospital stay (P<0.001) and postoperative complications (P=0.037). Multivariate analysis showed that intravenous fluid infusion at postoperative day 1 (POD1) (OR=1.001, 95% CI: 1.001-1.002, P=0.001) and duration of stoma ≥6 months (OR=2.005, 95% CI:1.155-3.657, P=0.014) were independent risk factors for delayed flatus. CONCLUSION: Increased intravenous fluid infusion at POD1 and duration of stoma ≥6 months were related to delayed recovery of gastrointestinal function after ileostomy reversal for rectal cancer patients.