If you’re a woman, you have a 1 in 8 chance of developing breast cancer during your lifetime. While there’s no way to know for sure who will get breast cancer, there are reasons you may be at greater risk to get the disease. We hope that this information can empower you to take steps to reduce your risks, such as staying on top of breast cancer screenings.

Below, we list the top risk factors and answer the most common questions about the causes of breast cancer.

What are breast cancer risk factors?

“A lot of times, women think family history is the biggest risk factor for breast cancer,” says Dr. Rae Ann Williams, who leads the Internal Medicine Department at HealthPartners. “But the data tells us that most women who are diagnosed with breast cancer don’t have any family history of the disease.”

In fact, more than 80% of breast cancer is found in women without a family history of the disease. So, even if your mother and sister are free from breast cancer, it’s still important to get regular screenings.

Here are the top risk factors for breast cancer:

  • Being an older woman – Most of the time, breast cancer is found in women who are over age 50.
  • Certain genome changes – Certain genetic mutations like BRCA1 or BRCA2 make breast cancer more likely. These mutations can cause hereditary breast cancer and can be passed down from your parents.
  • Weight – Being overweight or not getting enough exercise can increase your chances of breast cancer.
  • Menstrual and reproductive history – Your risk is higher if you got your period before age 12 or didn’t start menopause until after 55. Having your first child at an older age or never giving birth can also increase your chance.
  • Race and ethnicity – Breast cancer is more common in white women. However, African American and Hispanic women are more likely to have advanced breast cancer that spreads to other parts of their bodies.
  • Family history of breast cancer or ovarian cancer – Though family history is a small risk factor, you are more likely to get breast cancer if you have a mother or a sister with the disease.
  • Breast density – Having dense breast tissue (a greater proportion of glandular tissue compared to fatty tissue) is normal. But having dense breast tissue does increase your risk of breast cancer. And because tumors are harder to spot among dense tissue during a screening, there’s a chance that cancer won’t be found until it’s in a later stage.
  • Previous high-risk breast biopsy – If you’ve had a breast biopsy that showed abnormal cells, you have a higher chance of getting breast cancer.
  • Personal history of breast disease – If you’ve had breast cancer, you’re more likely to get it again.
  • Use of radiation or specific drugs – If you’ve received radiation to the chest before age 30 or took the drug diethylstilbestrol (DES) to prevent miscarriage, you may be considered higher risk.

Common questions about breast cancer causes

Does progesterone cause breast cancer?

Taking hormonal replacement therapy (HRT) medications that combine progesterone and estrogen for menopause symptoms increases your chance of breast cancer by about 75% while you’re on the medication. But once you stop taking the medication, your risks go down.

It’s safest not to use progesterone for menopause. But if you need relief from your symptoms, there are ways to reduce the risks of breast cancer from HRT. These options may include using estrogen-only therapy or reducing how long you take medicines that include progesterone.

If you are going through menopause, talk to your doctor about how you can manage your symptoms while limiting your risks of breast cancer.

Does birth control cause breast cancer?

Taking birth control pills increases your risk by about 20-30% while you take them. This risk continues for about 10 years after you stop. But your chance of getting breast cancer is lower during your reproductive years, so the benefits of birth control likely outweigh the risk.

Does hair dye cause breast cancer?

A large study called the Sister Study found that women who regularly use permanent hair dye or hair straightener are more likely to develop cancer.

Using permanent hair dye increases breast cancer risk by 45% for African American women and 7% in white women. But the use of temporary hair color did not appear to increase risk of breast cancer.

Women who straightened their hair within 12 months of the study had an 18% higher chance of getting breast cancer. A woman’s chance of getting breast cancer also increased based on the frequency of hair straightening. For example, women who straightened their hair every 5-8 weeks had an increased risk of 31%.

So, does this mean you should quit dying and straightening your hair? Should you switch to a temporary dye? It’s really up to you, but if you have more questions or concerns, talk to your doctor.

Can smoking cause breast cancer?

Tobacco use is the single largest preventable cause of cancer in the world. By quitting smoking (or never starting) you reduce your risks of numerous types of cancer, including lung, larynx, mouth, esophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum.

It’s also likely that quitting tobacco will also reduce your risk of breast cancer. Some studies show that people who smoke for more than 10 years have a slightly increased risk of getting breast cancer, especially if they started before having their first child. It’s also possible that heavy secondhand smoke exposure increases breast cancer risk in postmenopausal women

Does drinking alcohol cause breast cancer?

Drinking alcohol has also been shown to increase the risk of breast cancer – as well as other cancers throughout your body. And the more you drink, the more the risk increases. It’s best not to drink at all, but limit yourself to one alcoholic beverage a day if you do drink.

Do certain foods cause breast cancer?

People sometimes ask about certain foods – such as lunch meat, cheese, sugar and fat. While it’s good to be concerned about nutrition, the truth is that specific foods aren’t generally a primary cause of breast cancer.

Still, there are studies that suggest that these foods might increase your risks:

  • Dairy products. It’s unclear if eating dairy products can increase your chance of breast cancer. Some studies show increased breast cancer risk from drinking milk that includes traces of growth hormones or eating high-fat dairy products like cheese. But other studies show that the calcium and vitamin D in milk products lower cancer risk.
  • Processed meats. Some studies show that eating a lot of processed meats like sausage, bacon and ham increases the relative risks of getting breast cancer.

Of course, eating an occasional cheese and bologna sandwich probably won’t increase your risks too much – assuming that your diet is generally healthy.

If you’re not eating a balanced diet, it’s important to take time to improve your nutrition. Unhealthy eating can increase your chance of breast cancer in another way – being overweight is one of the top risk factors for breast cancer.

Can stress cause breast cancer?

No. There is no evidence that high stress levels increase your chance of breast cancer. Still, managing stress is good for your overall health. So, take time for activities such as deep breathing, guided imagery and exercise.

Do underwire bras cause breast cancer?

No, wearing a bra during the day or at night does not cause breast cancer. There have been some suggestions that a bra underwire can cause cancer by drainage of lymph fluid from the lower part of the breast, but there’s no clinical proof to support this.

Does deodorant cause breast cancer?

You many have heard that deodorants and antiperspirants containing aluminum can cause breast cancer. However, there’s no strong evidence showing this to be true.

So why do some people believe this? It has to do with how deodorants work. When aluminum is used as the active ingredient in an antiperspirant or deodorant, it forms a temporary plug in the sweat duct to prevent sweat from coming to your skin’s surface. The theory is that if the aluminum builds up in your body, it can cause estrogen-like hormonal changes that lead to breast cancer.

So, does aluminum in deodorants cause breast cancer? There hasn’t been a lot of research to prove or disprove a relationship between deodorant and breast cancer. If you’re concerned, talk to your doctor or look for a deodorant that’s aluminum-free.

Recalls of spray deodorants with benzene contaminants

While the active ingredients in deodorant are generally considered safe, some spray antiperspirants could include benzene, which is not a normal ingredient in aerosol antiperspirant – it’s a contaminant that has been found in the propellant that allows you to spray the deodorant out of the can.

There’s no proof that benzene causes breast cancer, but high levels of benzene exposure can lead to other cancers such as leukemia and blood cancer of the bone marrow.

If you’ve been using a contaminated spray deodorant for a little while, it’s unlikely you’ve been exposed to enough benzene to affect your health. But it’s a good idea to visit the U.S. Food & Drug Administration website to ensure your product hasn’t been recalled. Spray deodorants are still safe, but if you have any concerns, you could switch to a stick deodorant.

Do breast implants cause cancer?

Breast implants can cause an exceptionally rare cancer called breast implant-associated anaplastic large-cell lymphoma (BIA-ALCL). This type of cancer affects the immune system rather than the breast.

It’s estimated that fewer than 10 people a year get BIA-ALCL. Still, if you have breast implants and notice swelling, fluid around the implant, pain, lumps, redness or changes in the size or shape of the breast, contact your doctor right away.

Do mammograms increase your risk of breast cancer?

Like other imaging tests such as X-rays, mammograms do expose people to very small amounts of radiation. But best practices say that the benefits of getting a mammogram far exceeds the risk of having one. If you have questions or concerns, it’s always a good idea to talk with your doctor about what’s best for you.

Reducing your breast cancer risks

The best ways to reduce your breast cancer risks are to get regular exercise, watch your weight, limit drinking and quit smoking. Most importantly, get regular mammograms, even if you don’t have any signs or symptoms of breast cancer. Often there are no visible signs in the early stages of breast cancer.

If you have questions or notice anything unusual about your breasts, make an appointment with your primary care doctor. And if you haven’t yet had a mammogram for breast cancer screening, talk to your doctor about when you should get your first mammogram – most women should start around age 40.

We offer mammograms at more than 30 locations across the Twin Cities and in western Wisconsin.