Construction and validation of a predictive model for recurrence after synchronous radiotherapy for locally advanced squamous esophageal cancer

Objective To discuss the risk factors affecting recurrence within 3 years after synchronous radiotherapy for locally advanced esophageal squamous carcinoma, and construct and validate a recurrence prediction risk model. Methods A total of 156 patients with locally advanced esophageal squamous carcinoma who were admitted to Department of Radiotherapy, the Affiliated Hospital of Xuzhou Medical University from June 2017 to June 2019, were enrolled and their clinical data were retrospectively analyzed. Then, 156 patients were randomly divided into two groups: a training cohort (n=109) and a testing cohort (n=47) in the ratio of 7∶3. The risk factors for recurrence within 3 years in the training cohort were analyzed. A nomogram was constructed, and the predictive efficacy of the model was validated by calibration curves and clinical decision curves in the training and testing cohorts. Results Among the 156 patients, 87 patients were histologically or imaging confirmed with recurrence within 3 years, with a recurrence rate of 55.77%. According to univariate and multifactorial analyses, systemic immune inflammation index (SII)≥643.8, prognostic nutritional index (PNI)<48.05, lymph node metastasis, and poor differentiation were independent risk factors for recurrence within 3 years for locally advanced squamous esophageal cancer after synchronous radiotherapy (P<0.05), and these risk factors were included in the prediction model. The calibration curve showed a good fit between prediction and reality, and the clinical decision curve suggested that most patients were clinically benefited. Conclusions SII and PNI are the predictive factor for recurrence within 3 years after simultaneous radiotherapy for esophageal cancer. The nomogram model can provide evidence for clinicians to comprehensively assess disease and develop individualized follow-up monitoring programs.