Purpose: The role of adjuvant chemotherapy (ACT) in treating patients who have colorectal liver metastases (CLM) and undergo liver metastasectomy (LMS) is unclear in this patient population. We aimed to compare the mortality of patients receiving different ACT (i.e., oxaliplatin-based, irinotecan-based, and 5-fluorouracil-only (5FU)) and different treatment frequencies.
Methods: We included 2583 patients with CLM who underwent LMS (including synchronous LMS [SLMS] and metachronous LMS [MLMS]) in this retrospective cohort study. We used Cox proportional hazard model to obtain hazard ratios (HRs) for mortality. The reference group was 5FU-only ACT when comparing ACT type and the reference group was treatment for ≤ 3 times when comparing ACT frequency.
Results: In SLMS patients, oxaliplatin-based ACT (HR = 0.78) and receiving ACT for ≥ 4 times (4-6 times, HR = 0.61; 7-9 times, HR = 0.69; 10-12 times, HR = 0.66) were associated with lower risk of mortality. In MLMS patients, oxaliplatin-based ACT (HR = 0.52), irinotecan-based ACT (HR = 0.64), and receiving ACT for 10-12 times (HR = 0.65) were associated with lower risk of mortality.
Conclusions: In SLMS and MLMS patients, patients who received oxaliplatin-based ACT were more likely to survive than patients who received 5FU-only ACT. In MLMS patients, patients who received irinotecan-based ACT were also more likely to survive than those who received 5FU-only ACT. We recommend a course of at least four to six times of ACT after LMS in this patient population.
Keywords: Adjuvant chemotherapy; Colorectal cancer; Irinotecan; Liver metastasis; Oxaliplatin.