c-myc mRNA overexpression is associated with lymph node metastasis in colorectal cancer

To elucidate the relationship between oncogene overexpression and malignant potential of colorectal cancer, the expression of three genes, c-myc, c-fos and c-Ki-ras was examined. Northern blot hybridisation was performed on fresh tissues excised from 35 patients with primary colorectal cancer. Overexpression of c-myc mRNA was evident in 25 of the patients (71%). Tumours with c-myc overexpression had a significantly higher frequency of lymph node metastasis than did those without (68 versus 20%, P < 0.05). The survival rate tended to be poorer (P = 0.06) in patients with c-myc overexpression (79% for 3 years) than in those without it (100%). We found no significant relationship between overexpression of the other two genes and pathological features. These findings suggest that c-myc overexpression is one parameter which can be used to determine the malignant potential of colorectal cancer.