UICC World Cancer Congress 2006

Objective:Breast cancer is the second most common cancer among Indian women, with a current CIR of 23.5 /100,000.Apart from the high-risk genes several low risk genes could also contribute to the development of breast cancer. These low susceptibility genes include those that are involved in carcinogen activation and inactivation, estrogen metabolism, growth factors and their receptors etc. Single nucleotide polymorphisms in these genes could contribute to changes in their functional efficiency and predispose to disease.

Methods:This is a case control study involving 250 consecutive cancer cases and 500 age-matched controls. Blood samples were collected from all the participants after an informed consent. DNA was extracted using DNAeasy kit and quantitated. PCR was done for the GSTM1 gene and PCR-CTPP for the p53R72P polymorphisms. The PCR products were run on agarose gels to check for products and their size. The p53 variants were sequenced to confirm the polymorphisms and these were included subsequently in all the runs as controls.

Results:GSTM1 was present in 74%of cases and in 78% of controls and was absent in 26% of cases and 22% of controls (Odds ratio=1.3;95%CI=0.86-1.8). The p53 genotype distribution in cases was 26.4% for Arg72 homozygous, 50% for heterozygous and 23.6% for Pro72 homozygous; in the controls it was 27%, 44.8% ,and 28.2% respectively (OR=0.79;95%CI=0.55-1.13).

Conclusion: This is the first study to give the genotype frequencies of the p53 R72P polymorphism in Indian breast cancer patients and controls. Although the null genotype for GSTM1 was associated with an increased risk, this did not reach statistical significance.