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Genotyping at multifactorial loci modified breast cancer risk
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2009 ASCO Breast Cancer Symposium
A three-locus genotype, when added to family history, changed the predicted 10-year risk for developing breast cancer in nearly one-third of women participating in a study conducted in the United Kingdom.
When presenting the results at the 2009 Breast Cancer Symposium in San Francisco, Amy Martin, a medical student at the University of Dundee, Scotland, said the single nucleotide polymorphisms FGFR2, TNRC9 and MAPKKK1 together increased risk for breast cancer.
“Combining SNP genotypes has shown the potential for clinically important change in status for patients,” she said. “SNP testing merits further investigation, so we feel that we need larger studies and further investigation into using SNPs to estimate individual breast cancer risk.”
The researchers calculated genotype RR for combined genotypes using data collected from 160 women attending Tayside Breast Cancer Family Clinic for a family history of breast cancer. Martin et al then determined the 10-year and lifetime risks for breast cancer for those women.
Using the three-locus genotype along with family history, the researchers said 29% of women would be reclassified for risk compared with classification using family history alone. Twelve percent were assigned a higher risk category; 17% moved to a lower risk category.
When the researchers compared their findings to results from a meta-analysis published by Pharoh et al last year, they found a total change of 14%, with 9% of women having increased risk and 5% having decreased risk.
When determining the 10-year risk for breast cancer, women in the United Kingdom are stratified into population-, moderate- and high-risk categories. Women are considered high risk if they have a 10-year risk greater than 8% and are likely to carry a mutation in a high penetrance gene. – by Jason Harris
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The application of genome-wide association findings to clinical populations and models is an important first step to risk-enhanced risk assessment and clinical utility. However, replication in other populations is necessary.
– Jeffrey N. Weitzel, MD
Chief of Clinical Cancer Genetics, City of Hope, Duarte, Calif.
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