Relationship of Th17/treg cells and radiation pneumonia in locally advanced esophageal carcinoma

Abstract

Background/Aim: Radiation pneumonia is a main side-effect that has limited the clinical usage of radiotherapy in locally advanced esophageal carcinoma. T helper cells 17 (Th 17) and T regulatory cells (Tregs) play an important role in inflammatory diseases. The balance between Treg and Th17 cells is a key factor in the progression of many inflammatory and autoimmune diseases. Whether Tregs and Th17 cells are predictive factors of radiation pneumonia has not yet been reported. In this study, we investigated the relationships of Treg/Th17 cells and radiation pneumonia in patients with locally advanced esophageal cancer who received radiotherapy. Patients and Methods: One hundred and forty-eight patients with locally advanced esophageal cancer who received radical and palliative radiotherapy were enrolled. The levels of Th17 and Treg cells in the blood of patients were detected using flow cytometry at the time point of pre-radiotherapy, 1st, 2nd, 3rd, 4th, 5th and 6th week from the start of radiation and 4 weeks after completion of radiotherapy. Radiation pneumonia was evaluated according to Radiation Therapy Oncology Group's acute radiation pneumonia standards, with the endpoint being grade 2 or above radiation pneumonia. Results: There were 24 cases of radiation pneumonia in 148 cases of locally advanced esophageal cancer patients who underwent radiotherapy. Th17 cells increased and, in contrast, Treg cells decreased in the radiation pneumonia group. The change in the ratio of Th17/Treg was more pronounced and the difference was statistically significant from the 5th week after irradiation compared to patients with no radiation pneumonia (p<0.05). There was no significant difference in dosimetric parameters, including V5, V20, V30 and mean lung dose (MLD) and clinical factors, such as gender, age, smoking history, history of surgery and chemotherapy. Conclusion: The ratio of Th17/Treg cells may be an effective predictive factor of radiation pneumonia.