Chemotherapy alone versus chemotherapy plus targeted therapy as adjuvant therapy for initially unresectable colorectal cancer liver metastases: a multicenter cohort study.

[BACKGROUND] There is no consensus on the adjuvant treatment regimen for patients with colorectal cancer liver metastasis (CRLM) who have achieved successful conversion after surgery. This study aimed to compare the efficacy and safety of chemotherapy alone (CA) versus chemotherapy plus targeted therapy (CT) as adjuvant therapy for CRLM patients.

[METHODS] Initially unresectable CRLM patients who were converted to hepatectomy with no evidence of disease between June 2013 and June 2020 were retrospectively analysed. The baseline characteristics were balanced between the CA and CT cohorts by using 1:2 propensity score matching (PSM). After PSM, disease-free survival (DFS) and overall survival (OS) were evaluated. A comprehensive subgroup analysis compared the efficacy between the cohorts, with DFS and OS assessed by using a stratified log-rank test and summarized by using Kaplan-Meier and Cox proportional hazards methods.

[RESULTS] After PSM, 66 CA and 132 CT patients were included. DFS and OS were similar between the CA and CT cohorts (median DFS: 8.5 vs 10.8 months; median OS: 51.7 vs 56.5 months; both > 0.050). In the CT cohort, subgroup analysis indicated a favorable trend of DFS for patients with // mutations and receiving up to four cycles of conversion therapy (_interaction, 0.005 and 0.013, respectively). In the //-mutated cohort, CT significantly improved median DFS compared with CA (11.3 vs 7.4 months; hazard ratio, 0.42; 95% confidence interval, 0.26-0.69; < 0.001).

[CONCLUSION] CT, as adjuvant therapy, effectively reduced intrahepatic and extrahepatic recurrence in initially unresectable CRLM patients. The patients with // mutations or undergoing up to four cycles of conversion therapy benefited more from CT than from CA.