Tumor-Associated Macrophages in Radiotherapy: Present Status and Future Prospects

Abstract

The tumor microenvironment (TME) is closely related to the effect of radiotherapy on tumor cells. The changes in the TME after radiotherapy affect tumor growth, invasion, and metastasis. Tumor-associated macrophages (TAMs) are the most abundant immune cells in the TME. Their aggregation, phenotype change, and various cytokines released by macrophages after radiation therapy significantly affect the response of tumor cells to radiation and are important targets for improving the therapeutic effect of radiation therapy in the future. However, the effect of radiation on TAMs and the specific mechanism by which TAMs affect sensitivity to radiotherapy are still unclear. In this review, we highlight recent advances in the effects of radiotherapy on the phenotype of TAMs, the mechanism by which radiotherapy recruits TAMs, and the effect of TAMs on the radiosensitivity of tumor cells. The possible use of TAMs as a potential therapeutic target in combination with radiotherapy with a focus on improving radioresistance and enhancing anti-tumor immune activity has also been discussed. This provides a theoretical basis for the combined use of radiotherapy and targeted TAMs therapy in the future to improve the efficacy of radiotherapy.