Chemotharapy plus targeted therapy regimen, as an adjuvant therapy, can effectively reduce the rate of both intrahepatic and extrahepatic recurrence in initially unresectable CRLM patients. Those with KRAS/NRAS/BRAF mutated tumors or cycle of conversion therapy ≤ 4 can benefit more from chemotharapy plus targeted therapyrather than from chemotharapy alone, with a tolerable toxicity profile.

This multi-center study enrolled consecutive patients with initially unresectable CRLM who underwent conversion therapy or radiofrequency ablation (RFA) and achieved no NED status between June 1, 2013, and June 30, 2020, from Zhongshan Hospital of Shanghai, Zhongshan Hospital of Xiamen, Cancer Hospital of Beijing. The inclusion criteria were as follows: (1) with histologically confirmed CRC; (2) with initially unresectable synchronous liver metastases (LMs); (3) accepted conversion therapy and successfully converted into resectable status; (4) underwent R0 intestinal and hepatic resection; (5) accepted adjuvant therapy. The exclusion criteria were as follows: (1) R1/R2 resection; (2) extrahepatic metastases; (3) accepted postoperative monotherapy; (4) lack of follow-up data. According to the adjuvant therapy regimen (with or without targeted therapy), the cohorts were divided into CA cohort and CT cohort. The study was approved by the ethics committee of three medical centers and was adhered to Good Clinical Practice guidelines and the Declaration of Helsinki. Written informed consent was obtained from all participants.

Inclusion Criteria:

1. Age ≥ 18 and ≤ 75 years;
2. Histologically confirmed CRC;
3. Initially unresectable synchronous liver metastases (LMs);
4. Accepted conversion therapy and successfully converted into resectable status;
5. Underwent R0 intestinal and hepatic resection;
6. Accepted adjuvant therapy.

Exclusion Criteria:

1. R1/R2 resection;
2. Extrahepatic metastases;
3. Accepted postoperative monotherapy;
4. Lack of follow-up data.

Initially unresectable CRLM patients who were successfully converted and achieved no evidence of disease status from June 2013 to June 2020 were retrospectively collected. 1:2 propensity score matching (PSM) was performed to balance the baseline characteristics between CA and CT cohorts. After PSM, 196 patients werethe disease-free survival (DFS) and overall survival (OS) were evaluated between two cohorts （CA:N=66, CT:N=132）.