A Study on the Accurate Evaluation of Pseudoprogression of Rectal Cancer Immunotherapy Based on Multitemporal and Multiparameter MRI

Inclusion Criteria9

• Rectal cancer confirmed by biopsy pathology;
• Clinical stage II-IV determined by imaging examinations;
• Decided by the MDT team to receive immunotherapy (monotherapy with PD-1/PD-L1 inhibitors or in combination with CTLA-4 inhibitors), without prior treatment of any other kind;
• Multiparametric MRI images of the rectum obtained within 2 weeks before immunotherapy, and at 6 and 12 weeks after treatment;
• Follow-up CT/MRI data available; evaluation conducted according to the iRECEST criteria, or surgical resection performed to obtain postoperative pathological results, which are necessary for assessing the efficacy of immunotherapy and diagnosing pseudoprogression versus true progression;
• Blood test parameters (IL-8, NLR, LDH, S100) and clinical indicators (KPS score, CEA level, T-stage) measured within 2 weeks before immunotherapy, and at 6 and 12 weeks after treatment;
• In cases where imaging suggests disease progression, pathological biopsy or surgical pathology results must be available.
• The overall survival period is more than 3 months, and the patient does not have any other uncontrollable diseases;
• The patient has been fully informed and has signed the informed consent form.