New study shows multiple risk factors do not increase overall breast cancer risk.

Nearly 40 million US women die of breast cancer each year, making it the second cause of death among US women overall.  While there is no cure, scientists do know genetics, obesity, alcohol consumption and hormone replacement therapy are all risk factors for breast cancer.

Until today, researchers assumed there might be dangerous interactions if a woman was genetically prone to breast cancer and had one or more of the lifestyle related risk factors, such as hormone replacement therapy.  It was thought a woman with these combined factors would be at especially high risk for the disease.  Now, from Britain comes some good news that shows this thinking was wrong.

According to a study published June 2 in the British medical journal, Lancet, scientists found that found that although genetic mutations and lifestyle choices both contribute to cancer, they do so separately and do not mix for a more deadly effect.

Using a statistical analysis to examine the relationship between genetic and lifestyle factors, British researchers studied 7,610 women with breast cancer and 10,196 women without it.  Each woman provided a blood sample for genetic testing and information about other risk factors including obesity, alcohol consumption and hormone replacement therapy.

Researchers studied genetic mutations that are carried in up to 60 percent of women and known to increase a woman’s breast cancer risk from 10 to 20 percent.  Not studied were the rare BRCA genes which dramatically increase the risk of breast cancer.

“There’s a danger of feeling you’re at the fate of your genes,” said Ruth Travis of the Cancer Epidemiology Unit at the University of Oxford and the study’s lead author. “But whatever you’re born with, there are things you can do to modify your risk.” Britain’s Medical Research Council and Cancer Research UK paid for the study.