Colorectal carcinomas occuring following ulcerative colitis in Japanese patients discussed in the literature were analyzed in order to review their characteristics.
1) Of the 74 cases reported from 1962 to November 1989, 29 were males and 45 were females. The sex differences in Japanese ulcerative colitis were almost 1: 1, so females with colorectal carcinomas occured more often than males.
2) Male patients had a bimodal peak in their 30's and 40's, while female patients had the peak in their 40's and 50's. More colorectal carcinomas were found among younger people than in the general population.
3) Universal colitis was the most common type of colorectal cancer occuring following ulcerative colitis. 57 patients out of 74 were classified into this type.
4) The duration of the disease prior to the diagnosis of colorectal cancer was generally 10 years or longer.
5) The rectum was the commonest site of cancer, and was seen in 44 cases out of 74. Rectosigmoid colon carcinomas occurred in 61 of 74 cases.
6) Histologically, colonic malignancy associated with ulcerative colitis was an adenocarcinoma, displaying a wide spectrum of differentiation. Poorly differentiated (4 males and 6 females) and signet ring cell carcinoma (3 males and 5 females) were also reported.
7) The so‐called type 4 tumor occurred in 3 males and 6 females out of a total of 74 cases. This type of tumor is usually rare in colorectal cancer.
8) Most of the patients with early carcinomas had suffered from ulcerative colitis for more than 15 years and the characteristics of their macroscopic appearance were protruded lesions.
9) Foci of dysplasia accompanied carcinoma in as many as 80% of the Japanese cases reported. (56 out of 74 cases)
Based on these, we should take consideration that:
1) Patients with pancolitis lasting more than 10 years whose forms are chronically active or intermittently active should be recognized as a high‐risk group. 2) Full colonoscopy every one or two years may be sufficient to find dysplasia as well as carcinoma even if the condition of disease is stable. 3) Protruded lesions should be biopsied to detect early cancer as well as dysplasia on colonoscopy. 4) A change in the disease condition, i. e. rectal bleeding, weight loss and a change of bowel habits should not be mistaken for an exacerbation of colitis and should be investigated without fail.
