Synchronous and metachronous tumours of colon cancer. A review of five years of experience (1999-2004).

The authors report on 30 synchronous cancer (19%) and 9 metachronous cancer (5.7%) observed in 5 years (1999-2004) in 158 patient operated for colon cancer, defining metachronous cancer a tumor arisen at least 6 months after the first one or further then 5 cm from the anastomosis of the first colon resection. International case records report an incidence of 0.6-14% for synchronous cancer and 1-8% for metachronous cancer. The incidence of synchronous cancer is increasing for the presence of more oncogenic factors in the environment, for the improvement in radiology and endoscopy, for the raise of medium life. In accord with other authors, they show that the main risk factor for the developing of metachronous cancer is the coexistence of colon adenomas at the moment of the diagnosis of the tumor. The various incidence percentages can be explained by different way of diagnosis and classification