[Multiple primary colo-rectal carcinoma--an analysis of 28 cases].

Of 226 cases with colo-rectal carcinoma treated, 21 (7.89%) had synchronous and 7 (2.63%) had metachronous multiple primary lesions. In these 28 cases, 13 (46.43%) were complicated by adenomatous polyp, in which 7 cases (53.85%) became malignant. The tumor in 9 cases (18.75%) of synchronous carcinoma was less than 1 cm in diameter and could not be palpated during operation. The early metachronous carcinoma could be detected by fiberendoscopy during follow-up. Its diagnostic accuracy can be improved by fiberendoscopy before operation and during follow-up.