Significance of signet-ring cells in patients with colorectal cancer

PURPOSE: We performed a retrospective study to determine the pattern of metastases and overall outcome of patients with tumors exhibiting a component of signet-ring cells comprising < 50 percent of the tumor mass. METHODS: Medical records of 753 patients with primary colorectal cancer were retrospectively studied. Patients who had tumors with < 50 percent signet-ring cells were classified as having a component of signet-ring cells. The outcome of patients with a component of signet-ring cells was compared to all patients with mucinous adenocarcinoma (defined as adenocarcinomas with ≤ 50 percent mucin) to all patients with adenocarcinomas with a component of mucin (defined as adenocarcinomas with < 50 percent mucin) and to 100 randomly selected patients with adenocarcinomas lacking mucin or signet-ring cells. RESULTS: Five percent of patients had a component of signet-ring cells, 3 percent had mucinous adenocarcinoma, 9 percent had a component of mucinous adenocarcinoma, and 83 percent had adenocarcinoma lacking mucinous or signet components. Patients with a component of signet-ring cells and mucinous adenocarcinomas metastasized predominantly to the peritoneum/ovaries (75 and 56 percent of metastatic cases, respectively) and rarely to liver/lungs. The pattern of metastases of patients with adenocarcinoma without mucinous or signet components predominantly involved the liver/lungs and rarely the peritoneum/ovaries (12.5 percent). The pattern of metastases for patients with a component of mucinous adenocarcinoma was intermediate between mucinous adenocarcinoma and adenocarcinoma without mucin or signet-ring component. No differences in survival in Stage IV patients were seen among the four subgroups. CONCLUSIONS: Patients with a component of signet-ring cells cancers, similar to mucinous adenocarcinoma, have a predisposition to metastasize to the peritoneum/ovaries.