Clinical Outcome of Signet Ring Cell Carcinoma and Mucinous Adenocarcinoma of the Colon

Background: The purpose of this study was to evaluate the clinicopathologic features andprognosis of signet ring cell carcinoma (SCC) and non-SCC mucinous adenocarcinoma(MC) and to compare them with those of nonmucinous adenocarcinoma(NMC) of the colon.Methods: From January 1995 to December 2003, 45 patients with SCC and 332 withMC were identified from prospectively collected medical records. The clinicaldata and outcomes were compared with those of 2984 consecutivepatients with NMC in the same period.Results: The mean age at onset of SCC was 54.3 years. This was significantly lowerthan those for MC (mean 59.5 years, p = 0.038) and NMC (62.4 years, MCvs. NMC, p < 0.01). The rate of spread of tumors in TNM stage IV viahematogenous routes (liver, lung, bone, and brain) was significantly lower inSCC patients (5/28, 17.9%) than in MC (40/104, 38.5%) and in NMCpatients (417/694, 60.1%). The rate of tumor spread via lymphatic drainage(systemic node) or seeding to the peritoneum was higher in SCC (23/28,82.1%) and MC patients (79/104, 76.0%), than in NMC patients (343/694,49.4%, p < 0.001). There was a higher proportion of poorly differ-entiatedtumors in SCC (32/42, 71.1%) than in MC (26/332, 7.8%) and NMC(203/2984, 6.8%). The 1-, 2-, and 5-year overall survival rates of patientswith SCC were 77.8%, 26.7%, and 11.9%, of those with MC, 81.6%, 65.9%,and 49.4% and of those with NMC, 84.1%, 73.3%, and 58.7%, respectively.Conclusion: The prognosis of SCC is poorer than that of MC and NMC. SCC patients hadmore locally advanced and almost no early-detected tumors, less hematogenicspread, and very poor surgical outcomes. The role of resection for latestage SCC should be carefully evaluated.