In this study, the Quintuple method was applied for early intervention of prehepatic CTC-positive bowel cancer patients without dominant liver metastasis, aiming to explore the blocking effect of the Quintuple method on the metachronous liver metastases of colorectal cancer. A one-arm randomized clinical trial was conducted, and the patients were grouped according to their treatment methods. The patients with metachronous liver metastases were used as the end point of the experiment to evaluate the blocking effect of quintuple therapy.

Patients diagnosed with colorectal cancer, clinical stage I to III, underwent radical surgery, and prehepatic CTC≥1 were enrolled. Patients were randomly divided into Conventional treatment group and Quintuple method treatment group. Patients in the Conventional treatment group received conventional treatment according to the NCCN Guidelines for Colorectal Cancer 2023 edition. For patients in the Quintuple method treatment group, Quintuple method intervention was adopted, that is, combined with SOX regimen chemotherapy, low-dose cetuximab targeted therapy and three-drug regimen of folic acid, vitamin A and metronidazole. Specific drug dosages were as follows: SOX regimen was administered every three weeks, d1 was given oxaliplatin intravenously, the dosage was 130mg/ m2 * patient's body surface area, d2-d15 was taken orally by Digio, 20mg three times a day each time. Cetuximab combined with chemotherapy was administered intravenously, once every three weeks, before oxaliplatin, and the dosage was 250mg/ m2 * patient's body surface area. Metronidazole 0.4g/ time, once a day; Vitamin A 25,000 units/time, once a day; Folic acid 0.4mg/ time, once a day. The last three drugs were continued until the end of all chemotherapy cycles. The above regimen lasted for 6 to 8 sessions, and enrolled patients were reviewed every 3 months for colorectal cancer-related tumor markers, including MRI and CT imaging. The primary endpoint was radiographically confirmed metachronous liver metastases, and the secondary endpoint was death, observed for 3 years.

Inclusion Criteria:

1. Ages 18-80 at the time of signing the informed consent;
2. Histologically or cytologically confirmed adenocarcinoma of the colon or rectum;
3. Radical surgery has been performed;
4. Imaging examination showed no liver metastasis;
5. Prehepatic CTC number ≥1;
6. The ECOG performance status is 0-1.
7. No combination of other life-threatening diseases;
8. Willingness and ability to follow scheduled visits, treatment plans, laboratory tests and other research procedures.

Exclusion Criteria:

1. Patients with non-primary colorectal cancer;
2. Patients with liver metastasis or other organ metastasis;
3. Patients without prehepatic CTC or whose prehepatic CTC were negative;
4. People who are severely allergic to one or more of the drugs required in the test;
5. Patients with severe underlying diseases of respiratory, circulatory, urinary and hematopoietic systems.