Key Takeaways

  • Breast cancer is linked to genetic mutations, with the BRCA1 and BRCA2 genes being the most common culprits, but lifestyle and environmental factors also play a significant role.
  • Lifestyle choices like limiting alcohol, avoiding nicotine, maintaining a healthy weight, and adopting a well-balanced diet may help reduce your risk.
  • Early detection through regular screenings and awareness of potential symptoms like lumps, nipple discharge, or changes in breast shape are crucial for better outcomes.

Breast cancer is caused by gene mutations to the DNA in breast cells. Exactly what triggers this change is unknown.

What is known is that there are risk factors that may increase your chances of getting breast cancer. Some of them, like age, family history, and dense breasts, can’t be changedTrusted Source. Others are determined by lifestyle factorsTrusted Source that can often be controlled.

In the United States, it’s estimated that around 30%Trusted Source of new cancer diagnoses in women will be breast cancer, according to the American Cancer Society (ACS). This makes early detection — and possible prevention — very important.

Breast cancer originates in breast tissue and is caused by changes, or mutations, in breast cell DNA. These mutations cause cells to grow abnormally and divide quicker than healthy cells do. The abnormal cells accumulate, forming a malignant (cancerous) breast mass, also known as a lump.

Your immune system may be able to successfully fight some abnormal cells. But the ones that continue to grow may spread or metastasize throughout the breast to the lymph nodes or other parts of the body.

When breast cancer spreads, the malignant tumors it causes in other places are still referred to as breast cancer.

What exactly triggers DNA changes in breast cells isn’t clear. Two people can have the same or similar risk factors, but only one might develop breast cancer.

The ACS estimates that there’s a 13% chanceTrusted Source a woman develops breast cancer during her lifetime. But there’s a 7 in 8 chance she never will.

Age is the most significant risk factor for breast cancer. Most breast cancer cases are diagnosed in people at a median age of 62 years oldTrusted Source.

But your genetics and external factors, like smoking, also have an impact. Genetic risk factors can’t be changed, but lifestyle choices that put you at higher risk can be altered.

It’s also likely that genetic and environmental risk factors impact many people when several are present.

Genetic risk factors

Sex

People assigned female at birth are at a significantly higher risk of getting breast cancer than those not.

According to the Centers for Disease Control and Prevention (CDC), only about 1 in every 100Trusted Source cases of breast cancer diagnosed in the United States is in a man.

Heredity

You can inherit a gene mutation that puts you at higher risk for breast cancer from either biological parent. About 5% to 10%Trusted Source of all breast cancer cases are caused by hereditary gene mutations. The most common type is a mutation in the BRCA1 or BRCA2 gene.

Your risk for breast cancer increases to 60%Trusted Source if you have a harmful BRCA1 or BRCA2 gene mutation. Your risk for ovarian cancer is also increasedTrusted Source.

Other inherited gene mutations can increase your risk as well, including:

  • PALB2
  • PTEN (causes Cowdensyndrome)
  • TP53 (causes Li-Fraumeni syndrome)
  • ATM
  • CDH1
  • STK11
  • CHEK2 (causes Peutz-Jeghers syndrome)

Family history

If you have several close relatives with breast cancer, you may be more likely to develop it. This is especially true if you have one or more first-degree relatives with breast cancer. A first-degree relative is a parent, sibling, or child.

Having just one first-degree relative with breast cancer doubles your chancesTrusted Source of getting it. Having two first-degree relatives triples your chances of getting it.

Having a family history of breast cancer may mean you share the same genetic mutation. But there are other potential explanations here that have nothing to do with genetics.

Menstruation and menopause

You may be more likely to develop estrogen receptor (ER)-positive breast cancer if you began menstruating at a younger ageTrusted Source, especially before you turned 12, or started menopause later than usual, especially after age 55.

This is because there’s a longer period of time when breast cells are affected by estrogen and, possibly, progesterone.

Research from 2020 found an inverse relationship between your age at your first period and breast cancer risk. This means your risk for breast cancer goes up as the age you were when you started menstruating goes down.

Never having given birth or being older during your first pregnancy also increases your lifetime exposure to estrogen.

If you have given birth, every 12 months that you nurse your child reduces your chance of getting breast cancer by about 4.3%Trusted Source. And having given birth at all reduces your chance by 7%.

Lifestyle risk factors

Smoking

Smoking cigarettes and using nicotine products modestly increasesTrusted Source the risk of breast cancer. Starting smoking at a younger age puts you at greater risk.

Smoking also increases your risk to a greater degree if you have a family history of the disease.

Smokeless tobacco, which includes vaping, is also a risk factor based on some preliminary datasets.

Alcohol consumption

Alcohol is a known carcinogenTrusted Source that’s causally related to breast cancer risk.

The greater your alcohol intake, the higher your risk may be. Even one drink per day increases the risk of ER-positive breast cancers in both premenopausal and postmenopausal women.

More research from 2020 also shows a linear relationship between alcohol and breast cancer starting at any drink per day. This means your risk increases as you drink more alcohol.

Environmental exposure to toxins

Toxins and chemicals can be found in:

  • soil
  • water
  • dust
  • air
  • personal care products
  • household products
  • packaged foods

Some toxins are known as endocrine disruptors or endocrine-disrupting compounds. These toxins can mimic the effects of estrogen in the body and may increase breast cancerTrusted Source risk as they are known carcinogens. Endocrine disruptors include:

  • BPA (bisphenol A)
  • DDT
  • heavy metals, including arsenic, lead, and mercury
  • phthalates
  • atrazine

Diet

Certain foods may increase your risk of breast cancer, according to research. Foods to limit or avoid include:

Obesity

Because fat cells produce estrogen, being overweight or obese can be a significant risk factor — as is having a sedentary lifestyle, which may contribute to increased weight.

Women who’ve previously had breast cancer or are postmenopausal have an even higher risk if they’re overweight or are living with obesity.

A 2021 reviewTrusted Source found that obesity is linked with the development of breast cancer in women, specifically ER-positive breast cancer in postmenopausal women.

Hormone-based medications

Hormonal birth control, including the pill, ring, and IUD, may slightly increaseTrusted Source your breast cancer risk. If you have a family history of breast cancer, your risk may be higher.

Hormone replacement therapy (HRT) poses a much greater risk. HRT isn’t recommended for symptom relief of menopause in people who have other risk factors for breast cancer.

Know the symptoms

There are symptoms and warning signs of breast cancer that you may notice, especially if you do a monthly self-exam at home.

But many of these signs could be related to natural changes in your body or benign (harmless) conditions. This is why it’s important to talk about any changes in your breasts with a healthcare professional.

Signs and symptoms to look for include:

  • lump on the breast, collarbone, or under the arm that doesn’t go away on its own after your period
  • breast pain that doesn’t stop after your period
  • nipple discharge
  • nipple or breast dimpling
  • inverted nipple
  • changes to the skin of your breast that include discoloration, a rash, or being warm to the touch
  • change in breast or nipple shape

Early detection won’t stop you from getting breast cancer, but it can help to ensure a better outcome. Talk with a doctor about how often you should get a mammogram. If you have dense breasts, getting regular ultrasounds may also be beneficial.

Adjustments to your lifestyle may also help. These include:

If you’ve already had breast cancer

The following tips may aid with recovery and with avoiding breast cancer recurrence:

Breast cancer is caused by mutations in breast tissue cells. The underlying risk factors for breast cancer include genetics, environmental toxins, and lifestyle factors, but a definite cause hasn’t been identified.

Make proactive choices to reduce your risk of breast cancer. These include cutting down on smoking and alcohol use, as well as maintaining a healthy weight.