Background: The purpose of this study was to evaluate the clinicopathologic features and prognosis 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 with MC were identified from prospectively collected medical records. The clinical data and outcomes were compared with those of 2984 consecutive patients with NMC in the same period.
Results: The mean age at onset of SCC was 54.3 years. This was significantly lower than those for MC (mean 59.5 years, p = 0.038) and NMC (62.4 years, MC vs. NMC, p < 0.01). The rate of spread of tumors in TNM stage IV via hematogenous routes (liver, lung, bone, and brain) was significantly lower in SCC patients (5/28, 17.9%) than in MC (40/104, 38.5%) and in NMC patients (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-entiated tumors 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 patients with 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 had more locally advanced and almost no early-detected tumors, less hematogenic spread, and very poor surgical outcomes. The role of resection for late stage SCC should be carefully evaluated.