Table 2 Treatment strategy for patients who initially have resectable lung metastases

Middle and lower rectal cancer: T3–4 or N+

1. Preoperative systemic drug treatment/rectal neoadjuvant radiotherapy, resection of primary lesion/lung metastases, adjuvant chemotherapy

2. Preoperative systemic drug treatment/rectal neoadjuvant radiotherapy, resection of primary lesion, systemic drug treatment, resection of lung metastases, adjuvant chemotherapy

Middle and lower rectal cancer: T1-2N0;

Upper rectal cancer and colon cancer: T1–4N0–2

1. Preoperative systemic drug, resection of primary lesion, resection of lung metastases, adjuvant chemotherapy

2. Resection of primary lesion, systemic drug treatment, resection of lung metastases, adjuvant chemotherapy

3. Resection of primary lesion, resection of lung metastases, adjuvant chemotherapy