Prognostic implication of mucinous histology in resected colorectal cancer liver metastases

Background. Colorectal mucinous adenocarcinoma (MAC) is a subtype of colorectal adenocarcinoma with prominent mucin production associated with proximal location of tumor, advanced stage at diagnosis, microsatellite instability, and BRAF mutation. The prognostic implication of MAC in colorectal cancer liver metastases (CRCLM) is unknown. The purpose of our study was to determine the frequency and elucidate the prognostic implication of mucinous histology in CRCLM. Methods. The medical records of 118 patients who underwent CRCLM resection between 2000 and 2010 were reviewed. Clinicopathologic variables and outcome parameters were examined. Resected specimens were submitted to routine histologic evaluation. Patients were grouped according to the metastasis mucinous content: >50%, MAC;.<50%, adenocarcinoma with intermediated mucinous component (AIM); and without any mucinous component, non-MAC (NMA). Results. Mean follow-up after resection was 37 months. Tumor recurrence was, observed in 75% of patients. Overall survival and disease-free survival rates after hepatectomy were 61%, 56%, and 26%, 24% at 3 and 5 years, respectively. Tumors with mucinous component (AIM and MAC) were related to proximal location of the primary tumor and were more frequently observed in females. Multivariate analysis revealed that MAC was an independent negative prognostic factor (hazard ratio, 3.13; 95% CI, 1.30-6.68; P = .011) compared with non-MAC (NMA and AIM). Conclusion. MAC has an adverse prognostic impact compared with NMA, which may influence therapeutic strategy raising an important subject for discussion and future investigation.