Women who carry mutated forms of breast cancer genes called BRCA 1 and 2 account for at least 5% of breast cancer cases in the U.S. They are also at greater risk of developing ovarian cancer.
A survey suggests the risk in young women may be reduced by reversing symptoms related to the condition called insulin resistance, which is often an underlying cause of PCOS.
An international team of scientists found that women between 18 and 30 who carry BRCA 1 and 2 can significantly reduce their risk of developing breast cancer by losing weight. Research showed that women who lost at least 10 lbs between those ages reduced their risk of cancer by up to 65%. But the survey also produced evidence that gaining 10 lbs in the same age group increased the women’s risk of developing cancer before the age of 40.
Being overweight after the menopause was already known to increase the risk of women of developing the disease. But authors of the new study say it is the first to link the weight of women of reproductive age with cancer.
Researchers from the U.S., Canada and Poland, looked at more than 2,000 women carrying faulty or mutated BRCA1 or 2 breast cancer genes. BRCA 1 and 2 are tumor suppressor genes that, when functioning normally, help repair damage to DNA in a process that also prevents tumor development.
In 1994, researchers discovered that women who carry BRCA 1 or 2 mutations are at higher risk of developing both breast and ovarian cancer than women who do not have these genetic mutations.
The women in the new study were tested for BRCA1 and 2 genes and questioned about their weight at ages 18, 30 and 40. It was found that women carrying the BRCA 1 gene who lost weight saw the greatest benefit. At 18, they had an average weight of 142.5 lbs. By the age of 30, these women had lost a minimum of 10 lbs and an average of 18.6 lbs and experienced a reduction in risk of up to 65%. Weight loss also reduced the risk of cancer for women with the defective breast cancer gene BRCA 2 but not to a significant degree.
On the other hand, gaining weight substantially heightened the risk of breast cancer for BRCA 1 mutation carriers who had borne at least two children. These women increased their risk of being diagnosed with cancer before the age of 40 by 44% if they gained 10 lbs between the ages of 18 and 30.
The study suggests that carrying extra fat around the center of the body could affect ovarian hormones and glucose metabolism, increasing the likelihood of the onset of insulin resistance. This latter condition causes a reduction in insulin receptor sites on cell walls. The lack of sites means that insulin cannot perform its normal role of allowing sufficient blood glucose to pass through those walls to be used as energy. As a result, glucose and insulin levels become unbalanced – often an underlying cause of PCOS.
Excess glucose in the bloodstream ends up being stored as fat, which can result in obesity. The symptoms of insulin resistance can be reversed by weight loss via a balanced, nutritious diet and regular exercise.
But, if left unchecked, these symptoms may also lead to the cluster of cardiovascular diseases called metabolic syndrome or syndrome x. In addition, unbalanced levels of insulin can result in pre-diabetes, a reversible condition which, if neglected, may lead to full-blown type 2 diabetes.
Lead researcher Dr. Steven Narod of the University of Toronto, Canada, wrote: “The results from this study suggest that weight loss in early adult life protects against early-onset BRCA-associated breast cancers.
“Weight gain should also be avoided, particularly among BRCA 1 mutation carriers, who elect to have at least two pregnancies.”