Nomogram based on SIS predicting the survival of non-surgical thoracic esophageal squamous cell carcinoma treated by IMRT

Background: Several inflammatory markers have been reported to be associated with clinical outcomes in patients with esophageal squamous cell carcinoma (ESCC). This study was to evaluate several pre-radiotherapy serum inflammatory indicators, including the neutrophil / lymphocytes ratio (NLR), platelet / lymphocyte (PLR), systemic immune-inflammatory index (SII), systemic inflammation score(SIS), and compare which one has the highest predicted survival value. Finally, combining inflammatory markers with traditional prognostic factors, a new Nomogram model was developed to predict overall survival (OS) and progression-free survival (PFS) for ESCC patients receiving radiotherapy (RT) or chemoradiotherapy (CRT). Methods: This study retrospectively reviewed the data of 245 patients with thoracic esophageal squamous cell carcinoma (ESCC) underwent RT or CRT in the Fourth Hospital of Hebei Medical University from January 2013 to December 2015. The survival differences of these indexes were compared by the Kaplan-Meier method, and the univariate and the multivariate analyses were performed to determine these prognostic factors of overall survival (OS) and progression-free survival (PFS). Multivariate Cox proportional hazards regression models were used to create nomogram for OS and PFS.Results: 239 patients met the eligibility criteria. The estimated 1-, 3-, and 5-year OS and PFS rates were 74.6%, 36.8%, 26.5% and 58.4%, 31.3%, 20.5%, respectively, for the whole group. The difference in survival between OS and PFS was significant when univariate analysis were applied based on these inflammation-based measures. Multivariate analysis showed that tumor length, T stage, TNM stage, chemotherapy, SIS were predictive variables for OS and PFS in the multivariate model. The nomogram model established based on multivariate models of training data set had good predictive ability, the unadjusted C-index was 0.701 (95% CI, 0.662– 0.740) and 0.695 (95% CI, 0.656 - 0.734) for OS and PFS. Conclusions: This study show that SIS, as a comprehensive indicator of inflammation and nutrition, had the strongest predictive power for evaluating prognosis. Moreover, our nomogram can accurately predict OS and PFS after treatment and may provide guidance regarding adjuvant therapy and surveillance.