Megestrol Acetate in Improving Neoadjuvant Chemotherapy-Related Weight Loss in Locally Advanced CRC

Inclusion Criteria: * Adult males and females aged between 18 and 75 years old. * Histologically confirmed colorectal adenocarcinoma. * Immunohistochemistry showing pMMR or MSI status determined as MSS. * Clinical stage cTxN1-2M0, with or without MRF positivity, and with or without EMVI positivity. * ECOG performance status 0-1, with a life expectancy of ≥6 months. * Deemed suitable for preoperative mFOLFOX6 neoadjuvant chemotherapy following multidisciplinary team discussion. * Written informed consent has been obtained from the patients. Exclusion Criteria: * Patients with cardiac arrhythmias requiring anti-arrhythmic treatment (excluding β-blockers or digoxin), symptomatic coronary artery disease or myocardial ischemia (myocardial infarction within the past 6 months), or congestive heart failure greater than NYHA Class II. * Patients with poorly controlled severe hypertension. * Patients with a history of HIV infection or active chronic hepatitis B or C (with high-copy viral DNA). * Patients with active tuberculosis (TB) who are receiving anti-tuberculosis treatment or have received anti-tuberculosis treatment within 1 year prior to screening. * Patients with other active severe clinical infections (per NCI-CTC v.5.0). * Patients who have previously received chemotherapy. * Patients with a history of seizures requiring treatment (e.g., steroids or anti-epileptic therapy). * Patients with drug abuse or medical, psychological, or social conditions that may interfere with study participation or outcome assessment. * Patients with a known or suspected allergy to the study drug or any agents administered in relation to the trial. * Patients with any unstable condition that may jeopardize patient safety or compliance. * Pregnant or breastfeeding women, or fertile women not using adequate contraception. * Patients who refuse to sign the informed consent form.