Breast specialist Marisa Weiss, M.D., founder of breastcancer.org, shares the truth about 10 commonly held myths about breast cancer.

What is your risk of breast cancer? What about antiperspirants and breast cancer? What you don't know can hurt you. Misinformation can keep you from recognizing and minimizing your own risk of breast cancer or getting the very best possible care. 

Arm yourself with the facts. Here are 10 common myths about breast cancer:

Breast cancer only affects older women.
No. While it's true that the risk of breast cancer increases as we grow older, breast cancer can occur at any age. From birth to age 39, 1 woman in 231 will get breast cancer (<0.5% risk); from age 40 to 59, the risk is 1 in 25 (4% risk); from age 60 to 79, the risk is 1 in 15 (nearly 7%). Assuming you live to age 90, the risk of getting breast cancer over the course of an entire lifetime is 1 in 7, with an overall lifetime risk of 14.3%.

If you have a risk factor for breast cancer, you're likely to get the disease.
No. Getting breast cancer is not a certainty, even if you have one of the stronger risk factors, like a breast-cancer-gene abnormality. Of women with a BRCA1 or BRCA2 inherited genetic abnormality, 40 to 80% will develop breast cancer over their lifetime; 20 to 60% won't. All other risk factors are associated with a much lower probability of being diagnosed with breast cancer.

If breast cancer doesn't run in your family, you won't get it.
No. Every woman has some risk of breast cancer. About 80% of women who get breast cancer have no known family history of the disease. Increasing age -- just the wear and tear of living -- is the biggest single risk factor for breast cancer. For those women who do have a family history of breast cancer, your risk may be elevated a little, a lot, or not at all. If you are concerned, discuss your family history with your physician or a genetic counselor. You may be worrying needlessly.

Only your mother's family history of breast cancer can affect your risk.
No. A history of breast cancer in your mother's or your father's family will influence your risk equally. That's because half of your genes come from your mother, half from your father. But a man with a breast cancer gene abnormality is less likely to develop breast cancer than a woman with a similar gene. So, if you want to learn more about your father's family history, you have to look mainly at the women on your father's side, not just the men.