Circulating Tumor DNA Guided Therapeutic Strategies for CRC Patients With Small Pulmonary Nodules

• Local treatment (Procedure): Radical surgical resection, local radiotherapy, radiofrequency ablation (RFA) or interventional therapy (absolute alcohol or cryotherapy). The equipment used for RFA of lung lesions consisted of the radiofrequency generator (CelonLab POWER), cold circulation pump (Celon Aquaflow Ⅲ), radiofrequency needle electrode (Celon proSurge: T20, T30 and T40 is an electrode length of 20, 30 and 40 mm respectively, and maximum output power of 20, 30 and 40 W; Olympus Surgical Technologies Europe, Hamburg, Germany).

Primary outcomes

• Progression-free survival (PFS) in advanced colorectal cancer patients with metastatic small pulmonary nodules under ctDNA guided therapeutic strategies [From date of treatment until the date of first documented progression or date of death from any cause, assessed up to 36 months.]

Secondary outcomes

• ctDNA positive rate in colorectal cancer patients with metastatic small pulmonary nodules [4 weeks]
• ctDNA positive prediction rate (Consistent with histopathological result as the standard for comparison) [8 weeks]
• The ctDNA clearance rate after local treatment [8 weeks]
• The ctDNA clearance rate after chemotherapy in patients achieving NED (Cohort 2) [12 weeks]

Sex: All, ages: 18 Years to 80 Years

Inclusion Criteria:

1. Age ≥ 18 and ≤80 years old, regardless of gender;
2. Pathologically confirmed as adenocarcinoma of advanced colorectal cancer;
3. Lung lesions only, which was considered as metastatic by imaging consultation, and clinically diagnosed as lung metastasis of colorectal cancer;
4. Multiple lung lesions are allowed, but the maximum lesion diameter should be less than or equal to 2 cm;
5. For lesions larger than 1 cm, local treatment is planned, such as radical surgical resection or local radiotherapy, radio frequency ablation or interventional therapy (absolute alcohol treatment or cryotherapy);
6. Eastern Cooperative Oncology Group (ECOG) score 1 \~ 2;
7. The subjects (or their legal representative / Guardian) must sign the informed consent form, indicating that they understand the purpose of the study, understand the necessary procedures of the study, and are willing to participate in the study;
8. Surgical specimens or puncture specimens containing tumor tissue are available;
9. 20 mL of peripheral blood are available (10 mL per tube, two tubes in total);
10. Agreed to follow up for at least 2 years.

Exclusion Criteria:

1. The pathology was not confirmed by enteroscopic biopsy or biopsy of metastatic lesions;
2. Patients with stage I-III colorectal cancer;
3. Primary lung cancer, GGO, tuberculosis and other non metastatic conditions were excluded after diagnosis by imaging consultation;
4. Presence of metastasis other than lung;
5. Insufficient organ function, such as severe abnormal hemogram, abnormal liver and kidney function;
6. Any signs of severe or uncontrolled systemic diseases that the researcher believes may have a significant patient risk/benefit balance, including uncontrolled hypertension, severe infection, hepatitis B, hepatitis C and human immunodeficiency virus;
7. History of alcoholism or drug abuse;
8. Pregnant or lactating patients.