[Preneoplasias of the large intestine].

The adenoma-carcinoma sequence was related to size, histology and macroscopic appearance in 6770 adenomas. In ulcerative colitis prophylactic proctocolectomy is indicated only when neoplastic dysplasia is documented by repeated biopsies. In adenomatosis coli ileo-rectostomy is followed by rectal cancer at a low rate of 4% only in cases with polypectomy at 6-12 months interval, without this follow-up the risk is increased to 25%. Colectomy, proctomucosectomy, ileoanal anastomosis with a pouch completely eliminates the malignant potency. It is the operation of choice in all cases with diffuse rectal involvement. In 25 cases, operated without mortality and a morbidity of 20%, our preliminary results are promising.