Primary colorectal signet-ring cell carcinoma: clinicopathological features and postoperative survival.

PURPOSE: The objective of this study was to investigate the clinicopathological features and postoperative survival of primary colorectal signet-ring cell carcinoma. METHODS: Nineteen patients with primary colorectal signet-ring cell carcinoma were identified from a database of 5884 surgical patients with colorectal cancers treated surgically at Osaka University Hospital and affiliated hospitals between 1993 and 2007. The clinicopathological data of those patients were compared with those of 5792 patients with non-signet-ring cell colorectal carcinoma (5417 with well or moderately differentiated adenocarcinoma and 375 with poorly differentiated adenocarcinoma or mucinous carcinoma). RESULTS: All patients showed a tumor depth of over T3. Lymph node involvement occurred in 14 patients. Seven of 19 patients presented with distant metastasis at the time of diagnosis. The overall 5-year survival rate in primary signet-ring cell carcinoma was significantly lower at 24.1%, in comparison to 77.5% in well or moderately differentiated adenocarcinoma and 57.7% in poorly differentiated adenocarcinoma or mucinous carcinoma. Likewise, the postoperative survival in Stage III was also significantly worse. On the other hand, no significant difference was observed in Stage II or IV. CONCLUSION: The most important feature of primary colorectal signet-ring cell carcinoma is the advanced stage at the time of diagnosis. In addition, the postoperative survival is worse than for other types of colorectal cancer.