Modified Long-Course Radiotherapy Followed by Chemotherapy and PD-1 Inhibitor for MSS/pMMR High-risk Mid/Low LARC (MODIFI-RC-I)

"Long-course radiotherapy with selective CTV reduction (lower to S2/S3 level) + CAPOX + PD-1 inhibitor.~After treatment, patients will undergo TME surgery or a watch-and-wait approach, depending on response."

"Long-course radiotherapy with conventional CTV irradiation + CAPOX + PD-1 inhibitor.~After treatment, patients will undergo TME surgery or a watch-and-wait approach, depending on response."