Background Preoperative chemotherapy (PC) for colorectal liver metastasis (CRLM) is widely used to improve prognosis, but its clinical benefit has not been fully established. This study aimed to assess the effectiveness of PC for synchronous CRLMs, and to analyze the correlation between histological response to PC and survival. Methods We retrospectively analyzed the clinicopathological factors and outcomes of 69 patients who underwent initial hepatectomy for synchronous CRLM between 2004 and

more »

... 18 after receiving PC (PC group: n = 43) or who underwent upfront hepatectomy without PC (Non-PC group: n = 26). In the PC group, the patients were divided into two groups, Grade 1 (n = 27) and Grade 2/3 (n = 16) groups according to their histological responses to PC. Results The median survival and 5-year overall survival (OS) rates were 80.9 months and 61.5%, respectively, in the PC group and 71.7 months and 61.5%, respectively, in the Non-PC group (P = 0.867). Regarding recurrence-free survival (RFS) and remnant liver-RFS, there were no significant differences between the two groups (P = 0.087 and 0.291). However, in a subgroup analysis according to the histological response to PC, the median 5-year OS, RFS, and remnant liver-RFS in the Grade 2/3 group were significantly longer than in the Grade 1 group (OS: 66 vs. 53 months; P = 0.008, RFS: 15 vs. 6.7 months; P = 0.002, remnant liver-RFS: 62 vs. 8.3 months; P < 0.001). Surgical margin positive status (< 1 mm) was associated with a high remnant liver recurrence rate (hazard ratio 2.597, P = 0.008). Conclusion PC should not be routinely administered to all patients with synchronous CRLMs. However, some patients benefit from PC, and the histological response to PC had prognostic significance for patients with synchronous CRLM.