Breast cancer will likely affect one in eight women at some point during their lifetime, and the risks increase with age. However, the risk is not the same for all women in any given age group.
Genetic changes, including BRCA1 and BRCA2, are known to carry a higher risk, but now scientists say that even family members who test negative for the genetic differences are still at an increased risk of developing the disease.
The discovery of mutations on the BRCA genes has prompted many women to take drastic preventative measures, including Angelina Jolie and Sharon Osbourne, who sought double mastectomies when it was confirmed they had the breast cancer gene.
Now, a new study, published in Cancer Epidemiology, Biomarkers & Prevention, challenges the belief that a woman from a BRCA family who tests negative for her family-specific BRCA mutation has the same chances of contracting the disease as someone in the general population.
Lead author of the research Dr. Gareth R Evans, honorary professor at the Manchester Academic Health Centre at the University of Manchester, UK, explains:
"We found that women who test negative for family-specific BRCA2 mutations have more than four times the risk for developing breast cancer than the general population. We also found that any increased risk for breast cancer is largely limited to BRCA2 families with strong family history and other genetic factors."
He believes there are other genetic factors that may increase the risk of breast cancer.
"It is likely that these women inherit genetic factors other than BRCA-related genes that increase their breast cancer risk," Dr. Evans continues.
"About 77 single nucleotide polymorphisms [SNPs - genetic variations that can help track the inheritance of disease genes within families] are linked to breast cancer risk. Identification of additional SNPs is necessary to understand why some of the BRCA-negative women from BRCA families are at higher risk."
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