New combo therapy aims to save rectums from surgery

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Diagnosis: Histologically confirmed rectal adenocarcinoma. Preoperative Staging: Clinical stages cT2-4aN0-2. Tumor Location: Tumor's lower edge within 8cm from the anus, potentially affecting anal preservation or function. Metastasis Screening: Preoperative chest, abdomen, and pelvis CT to rule out distant metastasis. Biomarkers: Positive expression of pMMR (MSH1/MSH2/MSH6/PMS2) on tumor biopsy immunohistochemistry. Staging Methods: Combination of thoracic and abdominal pelvic CT, pelvic MRI, and endoscopic or transrectal ultrasound. Patient Characteristics Age: 18 to 70 years. Performance Status: ECOG score of 0-1. Life Expectancy: At least 2 years. Blood Counts: WBC \>4000/mm\^3, PLT \>100,000/mm\^3, Hb \>10g/dL (chronic anemia with Hb \< 10.0g/dL subject to multidisciplinary team review). Liver Function: Serum total bilirubin ≤1.5×ULN (≤3×ULN for Gilbert syndrome); AST and ALT ≤2.5×ULN. Renal Function: Serum creatinine ≤1.5×ULN or creatinine clearance \>50 mL/min. Other Criteria: Non-pregnant, not nursing, no other malignancies (except non-melanoma skin cancer or cervical carcinoma in situ) within the past 5 years, capable of providing informed consent, no severe comorbidities affecting survival. Prior Treatment No prior surgery, chemotherapy, or radiotherapy for rectal cancer. No prior biological therapy. No restrictions on previous endocrine therapy. Exclusion Criteria: Informed Consent: Lack of signed informed consent. Genetic Markers: Tumor biopsy indicating dMMR or MSI-H detected. Advanced Tumor Stage: Preoperative assessment showing tumor invasion of surrounding tissues/organs (T4b). Obstruction: Unresolved colonic obstruction; presence of tumor perforation. Metastasis: Evidence of preoperative distant metastasis. Cardiac Conditions: Arrhythmia requiring antiarrhythmic therapy (excluding beta-blockers or digoxin), symptomatic coronary artery disease or recent myocardial ischemia (within 6 months), or congestive heart failure above NYHA Grade II. Hypertension: Severe, poorly controlled hypertension. Infections: HIV infection, active chronic hepatitis B or C, other serious infections; active tuberculosis or anti-TB therapy within the past year. Organ Function: Poor fluid quality, organ function decompensation. Previous Treatment: History of pelvic or abdominal radiotherapy; multiple primary colorectal cancers. Neurological Conditions: Seizures requiring management (e.g., steroids, antiepileptic therapy). Cancer History: Other malignant tumors within the past 5 years, excluding cured cervical carcinoma in situ or basal cell carcinoma of the skin. Substance Abuse: Substance abuse or medical, psychological, or social conditions affecting study participation or result evaluation. Allergies: Known or suspected allergy to study drugs or related medications. Stability: Any unstable condition that may compromise safety or compliance. Reproductive Status: Pregnant or lactating women, or fertile women not using effective contraception.