This is an open-label, prospective, multicenter phase II clinical trial to evaluate modified short-course radiation (Radiation targeting the tumor bed without irradiating surrounding tumor-draining lymph nodes) combined with CAPOX and PD-1 Inhibitor (Tislelizumab) for patients with MSS middle and low rectal cancer. A total of 32 patients will be enrolled in this trial. The primary endpoint is the rate of pathological complete response (pCR). The organ preservation rate, tumor regression grade, long-term prognosis, and adverse effects will also be analyzed.
Patients who have a strong willingness to preserve the anus and are willing to receive neoadjuvant therapy.
Male or Female aged 18-75.
Patients diagnosed with low rectal cancer within 10 cm from the lower edge of the tumor to the anal verge by pelvic MRI and anorectoscopy, the clinical stage is cT2N+M0/cT3-4aN0/+M0, the lymph nodes are limited to the mesorectum, the circumferential resection margin is negative.
Histologically confirmed rectal adenocarcinoma; Genetic testing suggests MSI-L or MSS, or tumor biopsy immunohistochemistry reveals pMMR, that is, MSH1, MSH2, MSH6, and PMS2 are all positive.
Patients with a previous history of malignant tumors besides rectal cancer.
Patients with distant metastases before enrollment.
Patients with positive internal or external iliac lymph nodes are assessed by MRI or CT.
Patients with obstruction, perforation, or bleeding that require emergency surgery.
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China