Multiple colorectal cancers. A population based study]

Data from the Registry of Digestive Cancers in the C?te-d'Or (France) concerning 2,174 colorectal cancers diagnosed between January 1, 1976 and December 31, 1985, and followed through December 31, 1987 enabled us to study the risk of a second synchronous or metachronous intestinal cancer occurring in a given population. Several simultaneous cancers were seen in 59 patients i.e. 2.8 per cent of cases. Diagnosis was made during the initial diagnostic phase in only 32 per cent of cases. Simultaneous cancers occurred preferably on the same colonic segment (kappa = 0.4) and the distribution of the principal tumour did not differ from that of the cancers occurring alone. When polyps were associated with the cancer, the risk of discovering a second synchronous lesion was multiplied by 3.8. Survival in single or multiple synchronous lesions was identical for the same cancer stage. Twenty cases of second metachronous cancers occurred during follow-up of a first colorectal cancer, the relative risk (RR) compared to the C?te-d'Or population was 1.4 (NS). The risk was significantly high for Dukes' stage A tumours (RR = 2.9; P less than 0.01), with an exophytic appearance (RR = 2.1; P less than 0.05) or with adenomatous remnants (RR = 3.4; P less than 0.01). These data suggest that complete examination of the colon should be performed when the diagnostic of colorectal cancer is made to look for an associated cancer or polyps. Follow-up surveillance should address mainly patients with Dukes' stage A or Dukes' stage B carcinoma with an exophytic appearance or adenomatous remnants.