[Current status, controversy and challenge in the neoadjuvant immunotherapy of colorectal cancer]

Neoadjuvant therapy for colorectal cancer is widely used in rectal cancer, locally advanced colon cancer, and resectable metastatic and recurrent colorectal cancer. Mismatch repair deficient(dMMR) and microsatellite instablity-high (MSI-H) colorectal cancer patients who benefit from the efficacy of immune checkpoint inhibitors are expected to further improve the efficacy of traditional neoadjuvant therapy based on radiotherapy and chemotherapy. In this paper, the current status of immunotherapy (with emphasis on immune checkpoint inhibitors) is elucidated, and the opportunities of its application in neoadjuvant therapy are analyzed, including poor sensitivity of dMMR tumors to traditional therapy, good immune response of early tumors, predictable, manageable and controllable toxicity of immune checkpoint inhibitors. Colorectal cancer patients have growing and diverse needs to be met. Current controversies and challenges are analyzed, and the future directions are pointed out, including active screening of benefit groups, exploration of efficacy prediction markers, optimization of neoadjuvant immunotherapy models, attention to efficacy evaluation and new therapeutic endpoints. Neoadjuvant therapy should be effective, moderate and accurate based on the treatment target. It is the prerequisite and basis to guarantee medical safety and improve therapeutic effect to attach importance to the standardization and safety of clinical research and to pay attention to patients' interests and legal and ethical demands.