Myths and misinformation are rampant when it comes to risk factors and causes of breast cancer. Here’s what you need to be concerned about and what you don’t.

TRUE OR FALSE ?

Wearing antiperspirants and underwire bras can lead to breast cancer.

False. Several studies have found no link, said Dr. Victoria Seewaldt, director of the breast cancer prevention program at Duke University.

One theory was that using antiperspirants or wearing certain types of bras would impede lymphatic flow through the breast, causing cancer-causing toxins to build up, but that’s simply not true, said Dr. Virginia Kaklamani, assistant professor of oncology at Northwestern Memorial Hospital in Chicago.

Having more than one drink daily increases your risk.

True. Women who have two to five drinks daily increase their breast cancer risk 25 percent compared to those who abstain from alcohol, according to the American Cancer Society. The theory is that the way alcohol is metabolized leads to higher estrogen levels in the bloodstream, which ups your odds of developing the disease.

“Women should have less than a drink a day,” Seewaldt said. One drink is a 10-ounce beer, a 4-ounce glass of wine or one shot of hard liquor.

You’re destined to get the disease if you have a family history of it.

False. “Most people who have a mother who developed breast cancer after menopause only have a modest increase in risk compared to the general population,” said Dr. Claudine Isaacs, clinical director of the breast cancer program at the Georgetown University Medical Center.

Plus, there’s a difference between having a family history of the disease and having a genetic predisposition. If a close relative gets the disease (including on your father’s side), you have a family history. Carrying a mutation in one of the so-called breast cancer genes BRCA I or II indicates a genetic predisposition, which raises your lifetime risk 40 percent to 80 percent, Isaacs said.

That might sound high, but it still doesn’t mean you will definitely get breast cancer, Isaacs said. “There are many lifestyle factors that come into play, including whether you exercise and are at a healthy weight, that can mitigate your risk,” she said.

Plus, if you have a BRCA I or II mutation, you can take measures to lower your odds. For example, removing the ovaries before menopause reduces breast cancer risk by 50 percent. That’s why it’s important to discuss your family history — and your options — with your doctor.

Weight is a big factor.

True. If you’re obese or overweight, you have “an increased risk for developing breast cancer in postmenopausal years,” said Dr. Anne McTiernan, director of the prevention center at the Fred Hutchinson Cancer Research Center in Seattle. “We think it’s because these women have high levels of estrogens, testosterone and inflammatory markers such as C-reactive protein and insulin — all of which can cause breast cells to grow excessively.”

Who is at the most risk for developing breast cancer?

Since age is the primary factor after gender, women older than 50 are the key group. They account for 77 percent of cases.

What are some other factors?

Æ Menstrual periods beginning before age 12.

Æ Never having children.

Æ Having children after age 30.

Æ Radiation treatment for other cancers.

Æ Long-term use of hormone replacement drugs.

Æ High-fat diet low in fruits and vegetables.

Æ Exposure to pesticides.

Exactly what impact does a family history of breast cancer have? If your mother or a sister was found to have it before age 50, your risk is higher. But most women with breast cancer don’t have close relatives with the disease, studies have found, and most women who have a family history won’t develop it themselves.

What can be done to reduce the risks? Lifestyle changes can make a big difference:

Æ Stop smoking.

Æ If you drink alcohol, don’t have more than two drinks a week.

Æ Limit your consumption of red meat and other sources of animal fat (including dairy fat in cheese, milk and ice cream) because they might contain stored hormones or harmful pesticides.

Things you should do in your . . .

20s:

Æ Limit your radiation exposure. Ask if you can get an MRI or ultrasound instead of an X-ray or CT scan, an X-ray technique that uses particularly high levels of radiation.

Æ Watch your diet, particularly because younger women think they can get away with eating more and eating unhealthy foods. Eating three or more servings of red meat a week has been linked to an increased risk of breast cancer.

30s:

Æ Be sure to breastfeed. You’re not producing as much estrogen, which reduces your risk, said Dr. Carolyn Runowicz, director of the Comprehensive Cancer Center at the University of Connecticut.

Æ Lose the baby weight. Women who gain more than 36 pounds while pregnant and don’t lose it are 60 percent more likely to develop breast cancer after menopause, say researchers at Georgetown University.

40s:

Æ Go digital. Starting at 40, all women need a mammogram yearly. If you’re younger than 50 or have dense breasts, get a digital mammogram (it’s slightly more accurate than traditional X-rays).

Æ Keep moving. Studies show that women who keep exercising as they age suppress excess estrogen, which can fuel tumor growth.

50s AND 60s:

Æ Above all else, keep getting mammograms and try to take walks daily. Even though age is the No. 1 factor, research shows that women get less vigilant about checkups as they reach typical grandmother age.

Æ Skip hormone therapy if you’re 60 or older. Though research suggests that brief stints on hormone therapy to relieve menopausal symptoms are OK in younger women, it’s best to avoid it once you reach this age.