Single Arm and Phase II Clinical Trial of a Sandwich Regimen as XELOX Regimen and Capecitabine Alternate Administration Combined With Preoperative Intensity Modulated Radiation Therapy for pMMR Locally Advanced Rectal Cancer

In the treatment of locally advanced rectal cancer, the short-term and long-term efficacy of the traditional sandwich regimen has not reached satisfactory efficacy. For this reason, the concept of reducing the dose of postoperative chemotherapy or directly moving forward the full amount of postoperative chemotherapy was proposed, which is called total neoadjuvant therapy (TNT). However, TNT also includes the high toxicity of oxaliplatin in the whole process and the long time interval between the end of radiotherapy and the operation, which leads to fibrosis of the surrounding tissue, which increases the difficulty of surgical resection and makes it difficult to ensure good surgical specimen quality. In addition to this, there are issues that may increase the risk of potential disease progression in patients with poor treatment withdrawal. Therefore, appropriately reducing the intensity of chemotherapy and controlling the total duration of preoperative neoadjuvant therapy during radiotherapy is expected to alleviate the side effects of neoadjuvant therapy. Here, the investigators synthesized the characteristics of TNT and sandwich regimens and proposed a XELOX regimen and capecitabine alternate administration combined with preoperative intensity modulated radiation therapy.