Abstract:
Objective To establish the establishment of a predictive model for pathological complete response after neoadjuvant radiotherapy for locally advanced rectal cancer (LARC) and to validate the model.
Methods 241 patients with LARC treated with neoadjuvant radiotherapy at The Fifth People's Hospital of Chengdu from January 2022 to March 2024 were selected for retrospective analysis. Relevant factors that may affect the efficacy of the patients were collected, and the patients were divided into pathological complete response group and non-pathological complete response group according to the results of efficacy evaluation, comparing the clinicopathological characteristics, imaging indexes and laboratory indexes of the 2 groups, and the multifactorial Logistic regression was performed to establish a model after screening the potential variables by least absolute shrinkage and selection operator (LASSO) regression, and the results were visualized by Nomogram, and the model was verified.
Results Of the 241 LARC patients included in this study, 60 (24.90%) had complete pathological response. Multifactorial logistic regression analysis based on LASSO regression showed that pathological type, treatment regimen, extra-mural vascular invasion, rate of change of peak systolic velocity (PSV), neutrophil to lymphocyte ratio (NLR), and carcinoembryonic antigen (CEA) were the independent correlates of complete pathological response after neoadjuvant radiotherapy for LARC (P<0.05). The results of model validation showed that the area under the ROC curve was 0.836 with a 95% confidence interval (CI) of (0.773~0.899); the model curve was basically fitted to the ideal model curve as a diagonal. The results of clinical validity analysis showed the highest net benefit of predicting pathological complete response after neoadjuvant radiotherapy for LARC using the model of this study when the predictive probability threshold was 0.18~0.85.
Conclusion Pathological complete response after neoadjuvant radiotherapy in patients with LARC is influenced by the type of pathology, treatment regimen, and extra-mural vascular invasion, etc. The Nomogram model based on the influencing factors is used to predict pathological complete response after neoadjuvant radiotherapy in patients with LARC with a high degree of accuracy and discrimination.