Women looking to reduce their risk of developing breast cancer should avoid radiation from abdominal CT scans, certain hormone replacement drugs, and weight gain after menopause, the Institute of Medicine reported on Wednesday. Things not to worry about include hair dye and cell phones.
A comprehensive review of environmental factors reveals that no one factor makes a huge difference, said the influential, independent Institute.
A panel of experts appointed by the institute reviewed all the available evidence on how factors outside of genetics influence a woman’s chance of developing breast cancer, the second biggest cancer killer of U.S. women after lung cancer. Over the course of her lifetime, a woman born today has about a one-in-eight chance of developing breast cancer.
Many of the findings sound like common sense for healthy living: Don’t smoke, and do exercise and avoid excessive weight gain. Each of those steps also has the advantage of reducing risk for heart disease and other cancers. Avoiding alcohol can reduce the risk of breast cancer, it found, but may increase the risk of heart disease.
However, the report , commissioned by Susan G. Komen For the Cure, also identified a few potentially harmful medical interventions. It cautioned women to limit their exposure to ionizing radiation, particularly abdominal CT scans that involve big radiation doses and have been on the rise in recent years. (Mammograms, which deliver much smaller doses of radiation are worth getting, the authors note.) The report also recommended that postmenopausal women avoid hormone replacement drugs containing estrogen and progestin, unless medically necessary.
Now for the good news: None of the risk factors on its own has a huge impact. None even doubles the risk of developing cancer. An average white 50-year-old woman has a 2.4 percent chance of being diagnosed with breast cancer within 10 years. A woman with twice the risk has a 5 percent chance.
The study also reviewed possible risk factors that women shouldn’t worry about. The kind of radiation that comes from microwave ovens and cell phones doesn’t cause breast cancer, its evidence review found. Neither does hair dye.
The jury is still out on a few chemicals found in consumer products and industrial settings. The report found that there was no epidemiology showing that bisphenol A, a plastic used in cans, water bottles, and other plastic food packaging, increased cancer risk. But the expert panel said that laboratory research suggested it could, because it can resemble the hormone estrogen.
“BPA is one of those compounds that, in fact, does have estrogenic activity,” said Irva Herz-Picciotta, the chairwoman of the panel and the chief of environmental and occupational health at the University of California (Davis). “Individual women can make choices.”
The study, released at a meeting in San Antonio sponsored by the American Association for Cancer Research, also identified some areas for research. One big one: a more comprehensive look at whether risk factors matter more at different stages of life.
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