Chemoradiotherapy in Cancer Treatment: Rationale and Clinical Applications.

Chemoradiotherapy (CRT) refers to the combined administration of both chemotherapy and radiotherapy as an anticancer treatment. Over the years, CRT has become an established treatment for a diverse range of locally advanced solid tumours. The rationale for CRT is based on the two concepts of spatial cooperation and in-field cooperation, whereby the end goal is to achieve synergistic antitumour effects from the combination of both treatment modalities. CRT offers notable patient survival benefits and local disease control without significant long-term toxicities. Although the enhancement of cytotoxic effects inevitably increases damage to normal tissues as well as tumour cells, if the damage to normal tissue is lesser than that to tumour cells, CRT is still deemed beneficial. Thus, the search to optimise dose, timings and fractionation of CRT is of particular interest. Considering the recent success achieved with anticancer immunotherapies including immune checkpoint inhibitors, the combination of CRT and immunotherapy has emerged as an exciting field of research with the potential for significant clinical benefit. This report outlines the rationale underlying CRT and discusses its advantages through clinical examples focusing on anal, cervical, non-small-cell lung cancer and bladder cancer.