[Is mucinous colorectal adenocarcinoma a distinct entity?]

Several publications have demonstrated that mucinous carcinomas of the colon and rectum are associated with certain clinicopathological and genetic peculiarities that distinguish them from non-mucinous carcinomas. The principal aim of this study was to evaluate whether the biological behavior of mucinous carcinomas differs from that of intestinal carcinomas in patients undergoing surgery for colorectal cancer.

Between January 1993 and December 2000, 215 patients. underwent surgery in our hospital for colorectal cancer. The patients were divided into two groups according to histological type: tumors were intestinal in 169 patients (82%) and mucinous in 36 (17.6%). Patients undergoing non-resective surgery and those with tumors of other histological types (n = 10) were excluded.

The percentage of patients aged less than 50 years in the group with mucinous carcinoma was 19% (7/36) compared with 4% (7/169) in the non-mucinous group (p = 0.001). Regarding presenting symptoms, anemia was more frequent in patients with mucinous carcinoma (18.2% [n = 6] vs 5.7% [n = 8]) and a change in bowel habits was less frequent (15% [n = 5] vs 34.3% [n = 48]; p < 0.05). A total of 63.9% of mucinous carcinomas (n = 23) were located in the proximal colon (cecum, ascending and transverse colon) compared with 21.3% (n = 36) of non-mucinous carcinomas (p < 0.001). Surgical intention was palliative in 41.7% (n = 23.7) of mucinous carcinomas and in 23.7% (n = 40) of non-mucinous carcinomas (p < 0.05). The mean tumoral size was 6.2 2.5 cm in mucinous carcinomas and 4.7 2 in non-mucinous carcinomas (p = 0.001). Patients with mucinous carcinoma presented a higher percentage of nodal and distant metastases and a lower percentage of early stage tumors (p < 0.05). However, no differences were found in survival between the two histological types.

Mucinous tumors were more frequently located in the right colon and in patients less than 50 years old and were more likely to be in more advanced stages than non-mucinous tumors but no differences were found in survival according to tumor type.