An assessment of the mucous component in carcinoma of the colon and rectum.

It has been said that the prognosis of mucinous carcinoma of the colon and rectum is unfavorable. To determine the clinicopathologic significance of carcinomatous lesions with marked mucous production, the ratio of the area where there was significant mucous production (mucous component [MC]) to the area of the whole tumor on a tissue slice (area ratio) was determine by measurement with a digitizer in 281 patients with carcinoma of the colon and rectum. The MC was observed in the largest cross-section of the tumor in 85 patients (30.2%). Of these 85 patients the MC area ratio was less than 10% in 42. In the 43 patients with an area ratio of 10% or more, no particular relationship was observed between the area ratio and the frequency of cases. If no MC was observed in the largest cross section of the tumor, the MC ratio in other regions of the tumor was almost 0. In the patients in whom the MC area ratio in the largest cross-section was less than 10%, the MC area ratios in other sites of the tumor showed only a small variance, but in the patients with an MC area ratio of 10% or more, a large variance was observed according to the site. The prognosis for patients with an area ratio of 10% or more was less favorable than that for patients with no MC and with an MC area ratio of less than 10% (P less than 0.05). These results suggest that it is reasonable to handle the patients with an MC area ratio of 10% or more as a group.