-->Myth: Breast cancer is largely genetic.
Fact: Just 5 to 10% of cases are due to faulty breast cancer genes BRCA1 and BRCA2.
Even in women who have a family history, many cases are due not to specific gene mutations, according to the American Cancer Society, but, rather, to a combination of shared lifestyle factors and genetic susceptibilities. The truth is that scientists still have no idea what causes breast cancer. But one of the best ways to find out is to compare women who've never had it with those who have or who face an increased risk—the type of research the Army of Women hopes to contribute to.
-->Myth: Small-chested women have a lower risk.
Fact: Your bra size doesn't play a role in whether or not you get breast cancer.
All breast cancers develop in the cells that line the ducts or lobules—the parts that make milk and carry it to the nipple—and all women have the same number of these, regardless of breast size. What makes breasts bigger or smaller is generally the amount of fat and stroma (fibrous tissue), which research shows have little impact on cancer odds. Bottom line: All women 40 and older need regular mammograms.
-->Myth: Deodorant and antiperspirants cause breast cancer.
Fact: Skipping these toiletries won't keep your breasts cancer free.
One email rumor claimed that antiperspirant prevents you from sweating out toxins, which can then accumulate in the lymph nodes and cause breast cancer. But in 2002, researchers at the Fred Hutchinson Cancer Research Center in Seattle conducted a study to address this rumor—and found no link between deodorant or antiperspirant and breast cancer. A second rumor speculated that certain chemicals in antiperspirants, such as aluminum and parabens, may cause breast cancer because there is a lower prevalence of the disease in developing countries where women don't use these products. However, toxins are not usually released through sweat, and in Europe, where antiperspirants are not widely used, the rate of breast cancer is higher than it is in the United States. Finally, although a 2004 study found parabens in the tissue of breast cancer tumors, so far no studies have shown that these or any other chemicals in deodorants and antiperspirants cause breast cancer.
-->Myth: Wearing a bra increases your cancer risk.
Fact: There is no good scientific or clinical basis to support the claim that plain or underwire bras cause breast cancer.
This rumor appears to have started after a book called Dressed to Kill suggested that bras obstruct toxin-laden lymph fluid from flowing out of the breast. However, this was speculation based on a survey and no scientific evidence. Since then, major medical institutions, such as the National Cancer Institute and the ACS, have refuted the claim. If nonbra wearers do get breast cancer less often, it's probably because they tend to be thinner; obesity is a known risk factor.
-->Myth: Drinking from a plastic water bottle left in a hot car can cause cancer.
Fact: This rumor falsely claims that dioxins—a group of toxic chemicals associated with an array of health problems, including breast cancer—leach from the heated plastic into the water.