BACKGROUNDPrevious studies have shown conflicting results on the relation between clinicopathologic features and prognosis of patients with colorectal mucinous, signet-ring cell, or non-mucinous adenocarcinoma; only few such studies have been performed in China. This retrospective study analyzed data from our department to investigate clinicopathologic characteristics, prognosis and possible correlations of three histologic types - colorectal mucinous, signet-ring cell, and non-mucinous adenocarcinoma, to clarify the bases for observed differences which may lead to development of targeted therapies.

METHODSOf 2079 patients diagnosed with colorectal cancer between 1994 and 2007, 144 had mucinous, 25 had signet-ring cell, and 1837 had non-mucinous adenocarcinoma. Their clinicopathologic parameters and survival were analyzed using established statistical methodologies.

RESULTSMucinous and signet-ring cell adenocarcinomas were common in younger patients (P < 0.001). Location, size and disease stage differed significantly among the three types. Signet-ring cell tumors were more commonly found in the rectum than mucinous and non-mucinous adenocarcinoma (P < 0.001). Mucinous and signet-ring cell tumors presented in a later stage in life more often than non-mucinous adenocarcinoma, with lymph node involvement, serosal infiltration, peritoneal dissemination, and adjacent organ invasion (P < 0.01). The rate of radical resection, hepatic metastasis and local recurrence did not differ among types (P > 0.05). Compared with patients with non-mucinous adenocarcinoma, patients with mucinous and signet-ring cell tumors who underwent potentially curative resections or stage II/III disease had poorer long-term overall survival. Survival did not differ by type for patients with either stage I or IV disease (P > 0.05).

CONCLUSIONSMucinous and signet-ring cell adenocarcinoma have unique carcinogenesis and similar biologic behavior. Our study confirms that both histologic types, especially signet-ring cell tumors, are independent, negative prognostic factors for patients with colorectal cancer. Type does not appear to have a significant effect on survival when disease is either stage I or IV at presentation.