The Systemic Immune-inflammation Index (SII) Is an Independent Prognostic Factor for Patients With Recurrent Esophageal Cancer After Esophagectomy

Background/Aim: The systemic immune-inflammation index (SII) has been developed and reported to be a useful prognostic factor in various malignancies. The aim of the present study was to evaluate the clinical impact of the SII as a prognostic factor for esophageal cancer recurrence after esophagectomy. Patients and Methods: We retrospectively reviewed the medical records and collected data from consecutive patients with recurrent EC who received any treatment after recurrence at Yokohama City University from 2005 to 2022. Results: Ninety-four patients were included in this study. The median age was 69 years. The study included 83 men and 11 women. The median overall survival (OS) was 11.2 months. According to previous studies and 1- and 3-year OS rates, we set the cutoff value of the SII at 500 in the present study. Ninety-four patients were divided into an SSI-low group (n=36) and an SSI-high group (n=58). The 1- and 3-year OS rates were 84.9% and 44.7%, respectively, in the SSI-low group and 28.8% and 13.1%, respectively, in the SSI-high group. There were significant differences between the two groups (p<0.001). In the univariate and multivariate analyses, the SII was selected as an independent prognostic factor (hazard ratio=2.833, 95% confidence interval=1.555-5.161, p<0.001). The rate of first-line treatment introduction was 86.1% (31/36) in the SII-low group and 63.8% (37/58) in the SII-high group (p=0.019). In addition, the patients did not continue first-line chemotherapy because of disease progression, which was marginally significantly higher in the SII-high group than in the SII-low group. Conclusion: The SII was an independent prognostic factor. In addition, the SII affects the clinical course of treatment after recurrence. Therefore, physicians might have a chance to make better decisions for treatment and management of recurrent EC using the SII.