ASSOCIATION BETWEEN H-RAS MINISATELLITE AND COLORECTAL-CANCER RISK

Background: The H-ras locus has been suggested to play an important ro le in susceptibility to cancer. However, the results remain controvers ial. Methods: In order to elucidate the potential role of the H-ras lo cus in colorectal carcinogenesis, 142 colorectal tumors with matched n ormal samples were studied for genomic instability and loss of heteroz ygosity (LOH) and 143 healthy samples of white blood cell DNA were exa mined by PCR, for H-ras allelic polymorphism. Results: Nine percent of colorectal cancer patients constitutionally presented at least one ra re allele versus 1.4% of healthy individuals (P = 0.0034). The risk of developing colorectal cancer increased significantly with the presenc e of rare H-ras alleles (odds ratio = 7.10 and 95% confidence interval = 1.92-26.35). The genotype associating one common allele and one rar e allele was overrepresented in cancer patients (P < 0.01). No associa tions were observed between the rare alleles and tumor site or with th e aggressiveness of cancer. Low frequencies of LOH (5%) and genetic in stability (0.7%) at the H-ras locus were found in our colorectal cance r set. Conclusions: Consequently, the presence of uncommon alleles at the H-ras locus appeared to be an informative genetic marker.