Primary mucinous adenocarcinomas and signet-ring cell carcinomas of colon and rectum.

Of 352 patients with colorectal carcinoma followed for a minimum of 5 years after surgery, 39 cases (11.1%; median age 60 years) had mucinous adenocarcinoma, and 4 (1.1%; median age 62 years) had signet-ring cell carcinoma. Mucinous carcinomas were most frequently located in the rectum (61.5%) and in the sigmoid colon (15.3%) and presented with stage C and D disease in 41 and 15% of the cases, respectively. Disease recurrence was more frequently observed in patients with mucinous (51.7%) or signet-ring lesions (100%) as compared with adenocarcinomas. Five-year survival was 45 (median 48 months), 28 (median 27), and 0% (median 15 months) in patients with adenocarcinomas, mucinous adenocarcinomas, and signet-ring cell carcinomas, respectively (p < 0.05). Mucinous carcinomas of the rectum had had a significantly worse prognosis (5-year survival 17%, median 33 months) as compared with adenocarcinomas of the same site (5-year survival 34%, median 25 months; p < 0.05).