[Synchronous colorectal cancers].

The frequency of synchronous colorectal cancers ranges from 1.7 to 9.3% according to the series. The incidence of these cancers has been appreciated in various ways, according to variable diagnostic criteria, especially because some authors have included in situ carcinomas developing on degenerated polyps. A retrospective study of the synchronous cancers operated in our department from January, 1980 to August, 1990 allowed us to assess their frequency and location and to discuss the therapeutic choices. Two hundred and forty-nine patients with cancers of the colon or of the rectum have been operated during that period. Twelve (4.8%) presented with more than one colorectal cancer, all discovered simultaneously. The average age of the patients operated for synchronous cancer was higher that that of those operated of isolate cancer (68.8 years versus 63.3). Two thirds of the synchronous cancers were located in the sigmoid loop or the colon and, in one third of all cases, on non-adjacent segments of the colon. The frequent association of colic adenomatous polyps and of synchronous cancers--in one half of the patients in our series--must raise a discussion on the merits of systematic subtotal, or even total, colectomy in the treatment of synchronous colorectal cancers. This is also true for tumoral sites in 2 different segments of the colon. Segmental colectomy may be advocated in the other cases: cancers located on one segment, polyps located only on the resected segment of the colon, or polyps that can be resected via endoscopy.