Overexpression of c-myc and loss of heterozygosity on 2p, 3p, 5q, 17p and 18q in sporadic colorectal carcinoma.

Aim: The aim of the present study is to evaluate the prognostic influence of loss of heterozygosity on 2p, 3p, 5q, 17p and 18q, and c-myc overexpression on surgically treated sporadic colorectal carcinoma.

Methods: Tumor and non-tumor tissue samples from 153 patients were analyzed. Fifty-one percent of patients were male, and mean age in the series was 67 years. Tumors were located in the proximal colon in 37 cases, in the distal bowel in 37, and in the rectum in 79 patients. c-myc overexpression was studied by means of Northern blot analysis, and loss of heterozygosity through microsatellite analysis.

Results: c-myc overexpression was detected in 25% of cases, and loss of heterozygosity in at least one of the studied regions in 48%. There was no association between clinical and pathologic features, and genetic alterations. The disease-free interval was significantly shorter for patients with both genetic alterations; the presence of both events was an independent prognostic factor for poor outcome in the multivariate analysis (RR: 4.34, p < 0.0001).

Conclusions: The presence of both loss of heterozygosity and overexpression of the c-myc oncogene separates a subset of colorectal carcinoma patients who have a shorter disease-free interval after curative-intent surgery.