In this study, patients diagnosed with advanced gastrointestinal cancer including locally advanced gastric cancer, locally advanced colorectal cancer and colorectal cancer with liver metastasis. Tumor sample will be collected by endoscopy biopsy, needle biopsy or surgery, which will used for PTC drug screening.~Patients will be randomized to two groups. Patients in experiment group will receive neoadjuvant therapy based on PTC drug screening, and patients in control group will receive neoadjuvant therapy based on clinical experience. 2-4 cycles of neoadjuvant therapy will be administered. Patients appropriate for surgery will receive radical surgery after neoadjuvant therapy. Pathological response will be compared primarily between these two groups.~This is a randomized controlled, open-label and sequential designed clinical trial. All neoadjuvant therapy used in this study or for PTC drug screening comply with NCCN (National comprehensive cancer network) or CSCO (Chinese Society of Clinical Oncology) guidelines.
To explore the value of PTC drug screening technique in selecting neoadjuvant therapy for advanced gastrointestinal cancer.