Purpose: Alteration and overexpression of HER2 proto-oncogene have been implicated in the carcinogenesis and prognosis of ovarian cancer. We evaluated this hypothesis among women with ovarian carcinoma patients from Tiruchirapalli, Tamil Nadu, India.
Methods: Genomic DNA was extracted from 72 case patients and 288 control subjects and was examined for I655V polymorphism by PCR-RFLP based assay. Immunohistochemistry analysis was carried out in order to study the overexpression of HER2 protein. The observed number of each genotype was compared with that expected for a population in the Hardy-Weinberg equilibrium. In analysing the relation between genotype and overexpression of HER2 protein, Cochran-Mantel-Haenszel statistics was used.
Results: We found that 20.8% of the case patients and 16.3% of the control subjects were heterozygous for the Val allele and 10 case patients (13.8%) and 3 control subjects (1.1%) were homozygous for this allele (P < 0.001). Compared with women with Ile/Ile genotype, women with Val/Val genotype had an elevated risk of ovarian cancer. The genotype distributions were consistent with the Hardy-Weinberg equilibrium. The risk increased with the number of Val allele and women homozygous for the Val allele had 15-fold (OR = 15.3; 95%CI = 4.09-57.31) increased risk of cancer. The patients homozygous for the Valine allele showed strong HER2 protein expression.
Conclusion: The results showed that the valine allele may be an indicator of genetic susceptibility to ovarian carcinoma in the study population.