Implication of primary tumor location for the indication of preoperative chemotherapy in patients with colorectal liver metastases

Background: The benefit of preoperative chemotherapy for colorectal liver metastases (CRLM) remains uncertain. The aim was to clarify the effect of preoperative chemotherapy on CRLM according to the primary tumor location. Methods: Among a total cohort of 163 patients who underwent curative hepatectomy for CRLM, 36 patients had a right-sided and 127 had a left-sided primary tumor. According to the performance of preoperative chemotherapy, survival analysis was conducted and prognostic factors were identified. Results: Preoperative chemotherapy was administered to 17 patients (47.2%) with a right-sided and 74 (58.3%) with a left-sided primary tumor (P = 0.24). Among the patients who received preoperative chemotherapy, overall survival (OS) and disease-free survival (DFS) were similar between patients with right- and left-sided primary tumors (P = 0.36 and P = 0.44, respectively). Among the patients who underwent upfront hepatectomy, the OS and DFS of patients with a right-sided primary tumor were worse than those with a left-sided primary tumor (P = 0.02 and P = 0.025, respectively). Among the patients who underwent upfront surgery, the right-sided primary tumor was identified as an independent poor prognostic factor for OS (hazard ratio 3.44, P = 0.021). Conclusion: The existence of a right-sided primary tumor may be an indication of preoperative chemotherapy for patients with CRLM.