Resection of Liver Metastases From Colorectal Mucinous Adenocarcinoma

In Brief Objectives: To compare outcomes following liver resection of colorectal metastases (CRLM) from mucinous adenocarcinoma (Muc-CRLM) versus nonmucinous adenocarcinoma (non-Muc-CRLM). Background: Among colorectal adenocarcinomas, 10%–15% are mucinous and have worse prognoses than nonmucinous ones. Outcomes of liver resection for Muc-CRLM remain unknown. Methods: Among 701 patients undergoing liver resection for CRLM between 1998 and 2012, 102 (14.6%) had Muc-CRLM. Each was matched with a non-Muc-CRLM patient, based on tumor N status, disease-free interval (DFI) between primary tumor and metastases, CRLM number and diameter, extrahepatic disease, and preoperative chemotherapy. Results: Within the 2 groups, 69.6% of patients had N+ primary tumor, 72.5% had DFI of less than 12 months, 28.4% had 4 or more CRLM, and 22.5% had associated extrahepatic disease. 59.8% of patients received preoperative chemotherapy. Muc-CRLM patients had higher prevalences of right/transverse colon cancer (55.9% vs 29.4%; P < 0.0001) and K-ras mutation (67 patients tested, 61.8% vs 36.4%; P = 0.037), as well as lower response to preoperative chemotherapy (63.9% vs 85.2%; P = 0.006). Multivariate analysis showed Muc-CRLM to have lower rates of 5-year overall (33.2% vs 55.2%; P = 0.010) and disease-free survival (32.5% vs 49.3%; P = 0.037). Muc-CRLM recurrence was more often peritoneal (20.3% vs 6.5%; P = 0.024) and at multiple sites (47.5% vs 21.0%; P = 0.002), and had lower rates of re-resection (16.9% vs 43.5%; P = 0.002) and 3-year post-recurrence survival (11.7% vs 43.4%; P = 0.0003). Conclusions: Muc-CRLM patients strongly differed from non-Muc-CRLM patients, showing a lower chemotherapy response and higher K-ras mutation prevalence. Muc-CRLM appears to be a separate disease, which is associated with worse survival and aggressive rarely re-resectable recurrences. The present study shows that patients with liver metastases from mucinous colorectal adenocarcinoma strongly differ from those with nonmucinous tumors. Patients with mucinous histology showed lower responses to preoperative chemotherapy and higher prevalences of K-ras mutation. Liver resection in mucinous patients was associated with worse overall survival and aggressive recurrences that were rarely re-resectable.