A Clinicopathological Study of Multiple Colorectal Cancers

In 24 (6.7%) of 358 patients with primary colorectal cancer, multiple primary colorectal cancers were found. The male/female ratio was 16:8. The mean age was 56.8 years, and was 4.4 years younger than that of control group. In synchronous cases, 16 (70%) of 23 second lesions were less than 10cm from the first lesion, and almost all lesions that were more than 10cm from the first lesion was advanced cancers. The most frequent combination of lesions was advanced cancer-early cancer; however, in metachronous cases, all second lesions were advanced cancers. Patients with multiple primary colorectal cancers tended to have a family history of cancer and multiple cancers associated with other organs more frequently than patients without multiple primary colorectal cancers. The frequency of complication of benign neoplastic polyp of the colorectum in multiple colorectal cancers group was 83.3%, which was significantly higher than in the control group. In synchronous cases, multiple lesions could be diagnosed in 77.8% preoperatively and correctly, and the main reason why multiple lesions could not be diagnosed preoperatively was that the anal side lesion prevented the oral side lesion from being examined. At present, it is difficult to predict multiple primary colorectal cancers. Therefore, when colorectal cancer is found, careful preoperative examination, including other organs, and postoperative follow up are very important, bearing multiple primary cancers in mind.