Multi-Factor Analysis and Prediction of Late Rectal Toxicity after Radiotherapy for Cervical Cancer

Abstract

<h3>Purpose/Objective(s)</h3> This study is to explore the role of clinical and dosimetric parameters in predicting grade 2-4 rectal toxicity after intensity modulated radiotherapy and three-dimensional image-guided brachytherapy for patients with locally advanced cervix cancer. <h3>Materials/Methods</h3> A total of 104 patients with cervical cancer who were treated with radiotherapy and experienced late rectal toxicity from January 2016 to October 2021 were collected. late toxicity was defined as toxicity occurring or lasting more than 3 months after initiation of treatment and graded according to Common Toxicity Criteria for Adverse Events (CTCAE version 5.0). Collect the general clinical characteristics (age, pathological type, clinical stage, history of Cardiovascular diseases, radiotherapy type(radical/adjuvant radiotherapy), the dose of External therapy and brachytherapy, cycles of concurrent or adjuvant chemotherapy, etc.),and dosimetric factors data of the rectum(V5-V50, Dmin, Dmean, Dmax, D0.1 cc, D1 cc, D2 cc, D5 cc, etc.) of patients after radiotherapy, and statistically analyze the relationship between clinical factors, dosimetric factors, and grade 2-4 rectal toxicity. the statistical methods we used include independent sample t test, chi-square test, non-parametric rank sum test, binary logistic regression analysis, etc. <h3>Results</h3> The ratio of grade 2-4 rectal toxicity in the whole group was 42.31%(44/104).Univariate analysis showed that the occurrence of grade 2-4 rectal toxicity was significantly correlated with radiotherapy type (radical/adjuvant radiotherapy),brachytherapy dose, rectum V45,D2cc and D5cc.Factors with statistical significance (P <0.05) from univariate analysis were included in the multivariate analysis to show that rectum V45,D2cc and D5cc were independent risk factors for late rectal toxicity of grade 2-4(P=0.04,0.032 and 0.014).The ROC curve analysis is used to evaluate the combined detection of rectum V45,D2cc and D5cc,the area under the ROC curve for the dose, rectum occurrence of grade 2-4 rectal toxicity was 0.727 (95 %CI: 0.630-0.823,P<0.001),the best cut-off value was 0.355, the sensitivity was 0.707, and the specificity was 0.650. <h3>Conclusion</h3> In this study, V45, D2cc and D5cc were independent risk factors for late grade 2-4 rectal toxicity. A prediction mode was created on multivariable analysis, with three dose-volume parameters predictive of late grade 2-4 rectal toxicity.