A Clinical Study Based on FAPI-PET/CT Technology to Predict Pathological Complete Response After Neoadjuvant Chemoradiotherapy for MSS Rectal Cancer

Inclusion Criteria: * With my consent and signed informed consent, willing and able to comply with the planned visit, research treatment, laboratory tests and other test procedures; * Age 18-75; * Patients with a pathologically or cytologically confirmed adenocarcinoma of the rectum, all other histological types excluded; * The distance between the lower margin of the rectal tumor lesion and the anal margin \<12cm; * The physical status score (ECOG) of the Eastern United States Cancer Cooperative Group was 0-1 ; * T3-4/N+ was evaluated by pelvic enhanced MRI; * Had not received systemic anti-tumor therapy for colon cancer, including cytotoxic drugs, immune checkpoint inhibitor therapy, molecular targeted therapy, endocrine therapy, etc.; * Appropriate organ function based on the following laboratory test values obtained during the screening period: White blood cell count ≥3×109/L, neutrophil count ≥1.5×109 /L, platelet count ≥75×109 /L, serum total bilirubin ≤ 1.5× upper limit of normal (UNL), AST (SGOT) or ALT (SGPT) ≤ 2.5×UNL, serum creatinine ≤ 1.5×UNL; * Female subjects of reproductive age must undergo a negative serum pregnancy test within 3 days prior to the start of the study drug and be willing to use a medically approved highly effective contraceptive method (such as an IUD, contraceptive pill, or condom) during the study period and within 3 months after the last study drug administration; Male subjects whose partners are women of reproductive age should be surgical…