Utilizing CT imaging for evaluating late gastrointestinal tract side effects of radiotherapy in uterine cervical cancer: a risk regression analysis.

Background: Radiotherapy (RT) is effective for cervical cancer but causes late side effects (SE) to nearby organs. These late SE occur more than 3 months after RT and are rated by clinical findings to determine their severity. While imaging studies describe late gastrointestinal (GI) SE, none demonstrate the correlation between the findings and the toxicity grading. In this study, we demonstrated the late GI toxicity prevalence, CT findings, and their correlation.

Methods: We retrospectively studied uterine cervical cancer patients treated with RT between 2015 and 2018. Patient characteristics and treatment(s) were obtained from the hospital's databases. Late RTOG/EORTC GI SE and CT images were obtained during the follow-up. Post-RT GI changes were reviewed from CT images using pre-defined criteria. Risk ratios (RR) were calculated for CT findings, and multivariable log binomial regression determined adjusted RRs.

Results: This study included 153 patients, with a median age of 57 years (IQR 49-65). The prevalence of ≥ grade 2 RTOG/EORTC late GI SE was 33 (27.5%). CT findings showed 91 patients (59.48%) with enhanced bowel wall (BW) thickening, 3 (1.96%) with bowel obstruction, 7 (4.58%) with bowel perforation, 6 (3.92%) with fistula, 0 (0%) with bowel ischemia, and 0 (0%) with GI bleeding. Adjusted RRs showed that enhanced BW thickening (RR 9.77, 95% CI 2.64-36.07, p = 0.001), bowel obstruction (RR 5.05, 95% CI 2.30-11.09, p < 0.001), and bowel perforation (RR 3.82, 95% CI 1.96-7.44, p < 0.001) associated with higher late GI toxicity grades.

Conclusions: Our study shows CT findings correlate with grade 2-4 late GI toxicity. Future research should validate and refine these findings with different imaging and toxicity grading systems to assess their potential predictive value.