Mucinous histology of colon cancer predicts poor outcomes with FOLFOX regimen in metastatic colon cancer.

Mucinous adenocarcinoma (MA) of colorectal cancer seems associated with reduced responsiveness to chemotherapy. The overexpression of markers of resistance to fluorouracil and oxaliplatin has recently been demonstrated. We revised the outcomes of metastatic MA of the colon treated with FOLFOX. From January 2002 to December 2009, we treated 198 patients with metastatic colon cancer, of which 21 (10.6%) had diagnosis of MA and were compared with 42 control patients with non-mucinous adenocarcinoma (NMA). In MA group, three patients [14%; inhibitory concentration 95: ± 7.5%] reached partial response, and in NMA group, two patients obtained complete response and 16 obtained partial response with an overall response rate of 43% (inhibitory concentration 95: ± 7.6%) with a significant statistical difference (P = 0.027). Median progression-free survival for MA group was 4 months with respect to 8 months for NMA (P = 0.0001); regarding overall survival, we registered a median of 8 months with respect to 18 months for MA and NMA (P = 0.001). In multivariate analysis, MA histology, Eastern Cooperative Oncology Group performance status 2, more than two metastatic sites, and peritoneal metastatic involvement resulted in negative independent prognostic factors. Also in our study, MA is connected to poor prognosis and reduced activity of chemotherapy. In the absence of randomised studies, it may be convenient to analyse this subgroup of patients within the large trials carried out on colorectal cancer.