Ordinary colorectal adenocarcinoma vs. primary colorectal signet-ring cell carcinoma: study matched for age, gender, grade, and stage.

PURPOSE: This study contributes to the characterization of primary colorectal signet-ring cell cancer in contrast to ordinary colorectal carcinoma. Primary colorectal signet-ring cell cancer is a rare but distinctive primary neoplasm of the large bowel with still-controversial clinicopathologic features.
METHODS: Clinicopathologic features and survival data are evaluated in comparison with those of the ordinary colorectal adenocarcinoma (non-signet colorectal carcinoma) in a retrospective study matched for age, gender, grade, and stage.
RESULTS: In a series of 1,600 consecutive colorectal cancer patients since 1979, 14 patients (0.88 percent) with a signet-ring cell cancer were identified. Gender ratio was balanced, and mean age was 67.5 years. The majority of patients had an advanced tumor stage at the time of diagnosis (57.1 percent Stage IV and 35.7 percent Stage III). Median survival time was only 16 months. In a study matched for age, gender, grade, and stage, a lower survival rate was found for patients with signet-ring cell cancer, but the difference did not reach statistical significance. In contrast to non-signet colorectal carcinoma, signet-ring cell cancer was characterized by a significantly higher incidence of peritoneal tumor spread (64.3 percent) and a lower incidence of hepatic metastases (14.3 percent).
CONCLUSIONS: Signet-ring cell cancer represents a rare but distinctive primary neoplasm of the large bowel. It is frequently diagnosed in an advanced tumor stage, thus showing an overall poorer prognosis than nonsignet colorectal carcinoma. Usually only palliative surgery is possible. A high incidence of peritoneal seeding and a low incidence of hepatic metastasis is characteristic of signet-ring cell cancer.