Impact of Radiation Dose to Circulating Immune Cells on Tumor Control and Survival in Esophageal Cancer

The immune system is well known to exert tumor immunosurveillance effects, and that immune cells circulating in the peripheral blood affect tumor prognosis. The study investigated the effect of estimated dose of radiation on circulating immune cells (EDRIC) and tumor control for esophageal cancer patients treated with concurrent chemo-radiotherapy. A total of 146 esophageal cancer patients treated with radiotherapy between January 2016 and June 2020 were retrospectively identified. We determined EDRIC, known prognostic factors, and the association of these factors with progression-free survival (PFS) and overall survival (OS). The median follow-up was 17.9 months (2.7-60.4 months). The 3-year OS was 39.2%. Severe post-treatment lymphopenia was observed in 84.2% of patients. A negative correlation between EDRIC and absolute lymphocyte count was found ( = -0.679;