7.

Conversion chemotherapy for potentially resectable lesions^a,b,c

Stratification	Class I recommendation	Class II recommendation	Class III recommendation
a, For potentially resectable patients, 5-fluorouracil (5-FU)/leucovorin (LV) (or capecitabine) combined with oxaliplatin or irinotecan plus molecular targeted therapy should be selected. FOLFOXIRI ± bevacizumab can be used with caution in patients with a good performance status, who are young, and have a high tumor burden (3). For patients with successful conversion with R0 resection of primary and metastatic lesions, it is generally recommended to continue adjuvant chemotherapy after surgery to complete a total of six months of perioperative treatment. If the preoperative combination of targeted drugs is effective, whether to continue to use targeted drugs postoperatively is still controversial. b, It is recommended that imaging assessment be conducted every 6−8 weeks during conversion therapy. Surgery is recommended if the metastatic lesions are resectable. c, If the patient has a responsible or stable disease after 4−6 months of first-line treatment, maintenance therapy can be used or systemic therapy can be temporarily suspended. 5-FU/LV or capecitabine monotherapy ± bevacizumab is recommended for maintenance therapy due to low toxicity (4,5). The use of cetuximab in maintenance therapy has been poorly studied. d, Recently, many retrospective studies have shown that the prognosis of metastatic colon cancer with right-sided primary lesions (ileocecal junction to splenic flexure) is worse than that of left-sided primary lesions (splenic flexure to the rectum). Retrospective subgroup analysis data of randomized, controlled trials showed that the objective response rate and overall survival of cetuximab are both better than that of bevacizumab for patients with left-sided colorectal cancer. For patients with right-sided colon cancer, cetuximab shows minor advantages over bevacizumab in objective response rate but overall survival is worse than that of bevacizumab (6).
Suitable for intensive treatment (both RAS and BRAF wild-type)	FOLFOX/FOLFIRI ± cetuximabd (Level 2A evidence)	FOLFOX/CapeOx/FOLFIRI ± bevacizumab (Level 2A evidence); FOLFOXIRI ± bevacizumab (Level 2A evidence)	Hepatic arterial infusion chemotherapy or other local treatments (Level 2B evidence)
Suitable for intensive treatment (both RAS or BRAF mutations)	FOLFOX/CapeOx/FOLFIRI ± bevacizumab (Level 2A evidence)	FOLFOXIRI ± bevacizumab (Level 2A evidence)	Hepatic arterial infusion chemotherapy or other local treatments (Level 2B evidence)