Does the prognosis of colorectal mucinous carcinoma depend upon the primary tumour site? Results from two independent databases.

ABSTRACT

AIMS: Mucinous adenocarcinoma (MUC) is a commonly studied histological subtype of colorectal adenocarcinoma. However, the prognostic value of MUC remains unclear, particularly in patients stratified by the primary tumour site. We aimed to analyse the prognostic value of MUC in colorectal cancer. METHODS AND RESULTS: We utilized two independent data sets in this study (i) the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) data set, and (ii) the data set from a single Chinese institution (the Department of Surgical Oncology at the First Hospital of China Medical University). Patient survival was analysed using Kaplan-Meier survival curves, and comparisons were performed using the log-rank test. MUC occurred more frequently in patients who exhibited higher pT category, higher pN category, higher TNM stage, left-sided colon cancer and higher histological grade. Based on the SEER data set, MUC was an independent negative survival indicator in rectal cancer (HR 1.125, 1.056-1.199; P < 0.001). While there was no significant association in left-sided colon cancer (P > 1.000), MUC was an independent protective survival indicator in right-sided colon cancer (HR 0.925, 0.888-0.962; P < 0.001). CONCLUSIONS: MUC was associated independently with poorer outcome for rectal cancer and was an independent protective survival indicator in right-sided colon cancer. MUC exhibited a different outcome depending on tumour position for patients with colorectal cancer.