Primary signet-ring cell carcinoma of the colorectum

Background. Objective of the study was to investigate particular clinicopathological features of colorectal signet-ring cell carcinoma. Methods. The data of 34 patients with primary colorectal signet-ring cell carcinoma were compared with those of 4,458 consecutive patients with primary non-signet-ring cell colorectal adenocarcinoma between 1978 and 1999. For outcome analysis patients, after curative resection of signet-ring cell cancer, were matched for age, gender, tumour site and stage with patients suffering from poorly differentiated non-signet-ring cell colorectal adenocarcinoma. Results. Signet-ring cell carcinoma patients were significantly younger than patients with non-signet-ring cell colorectal adenocarcinoma (median age 60 years vs 64 years, P=0.033). The most common tumour sites were the rectum (47%) and the right hemicolon (29%). They presented with significantly more advanced tumour stages and a significantly higher frequency of distant metastases (44% vs 21%, P=0.002). The rate of curative resections was significantly lower (35% vs 79%, P<0.001). However, the prognosis after curative resection of signet-ring cell cancer was as poor as in poorly differentiated non-signet-ring cell colorectal adenocarcinoma of the same stage (5-year survival rate 46% vs 57%, p=0.935). Conclusions. Colorectal signet-ring cell carcinoma is characterized by diagnosis in more advanced tumour stages resulting in lower rates of curative resection. Prognosis is as poor as in non-signet-ring cell colorectal cancer of low differentiation in the same stage.