Short-course neoadjuvant radiotherapy of 5Gy × 5 fractions is recommended to be a standard treatment for the patients with ressectable stage II/III rectal cancer. While the effect of radiotherapy of 5Gy × 5f on the tumor microenvironment is still unclear. The purpose of this study was to evaluate the interactions between radiotherapy of 5Gy × 5f and the tumor immune microenvironment.
The changes in the number of immune cells, the changes of P-STAT1, P-STAT3, MICA, KIR, PD-L1 and Gal-1 in tumor before and after radiotherapy were assessed in mouse CT26 rectal cancer model. The effects of radiotherapy of 5Gy × 3f and 5Gy × 5f on HCT116, RKO, SW480,174T, DLD-1 cell lines were also investigated. Furthermore, clinical samples of patients with rectal cancer were analyzed. The changes of T lymphocytes in blood and T lymphocytes and NK cells in tumor before and after radiotherapy were tested. The infiltration of CD8 + T lymphocyte in tumor was studied as well.
In CT26 models, the radiotherapy of 5Gy × 5f promoted CD4 + and CD8 + T lymphocyte infiltration (P
Radiotherapy of 5Gy × 5f could promote the infiltration of CD4 + and CD8 + T lymphocyte in local tumor, and enhance the anti-tumor effect of NK cells and T lymphocytes. Short-course neoadjuvant radiotherapy of 5Gy × 5f have immune stimulatory effects for rectal cancer.
Clinical trial identification
Legal entity responsible for the study
Chinese National Natural Science Foundation (NSFC 8120175).
All authors have declared no conflicts of interest.