Drug Sensitivity Detection of Micro Tumor (PTC) to Guide Postoperative Adjuvant Treatment Strategy of Colorectal Cancer

This study is testing whether using a lab test — growing a miniature version of a patient's tumor in the lab (called a patient-derived tumor culture or PTC) and exposing it to different drugs — can help doctors choose the most effective chemotherapy for colorectal cancer patients after surgery. **You may be eligible if:** - You are between 18 and 75 years old - You have colorectal cancer confirmed by biopsy - You have had surgery to remove your cancer and need chemotherapy afterward - You have not received chemotherapy before surgery (no neoadjuvant therapy) - Your overall health score is adequate (ECOG ≤2) **You may NOT be eligible if:** - Your cancer has already spread to other organs (metastatic) - A tumor sample cannot be obtained - You are pregnant or breastfeeding - You have severe heart or brain complications - You have another active cancer - You have serious mental health conditions Talk to your doctor to see if this trial is right for you.