[Multiple colorectal cancers: properties and long-term prognosis].

In our own patient population with primary colorectal cancer (n = 1352, 1971-1984) we analyzed the frequency, characteristics and prognosis of multiple carcinomas. The overall incidence was 7.3% (4.5% synchronous and 2.8% metachronous carcinomas). Compared to single cancer synchronous tumors had a worse and metachronous tumors had a better 5 year-prognosis (58%, 43% and 86% respectively). This suggests that synchronous and metachronous colorectal carcinomas may be two biologically separate entities. Conclusions from our observations are discussed in regard to diagnosis, therapy and follow-up.