The truth is that everyone is at risk of breast cancer—but some of us are at a higher risk than others. Understanding our risk helps us take better care of our breast health.
There’s a lot researchers still don’t know about what causes breast cancer. Things we know affect risk are called risk factors. (Some risk factors increase risk and some decrease it.) There are many risk factors we can’t control—for example, being born female and getting older are the two most common risk factors for breast cancer. There are also some risk factors we can control, but no one of them alone can cause or prevent breast cancer.
So why think about risk? It’s all about what we do with that knowledge. When we know our risk factors, we can get on a regular screening schedule with our doctors and take other actions to reduce our risk.
While some tumors in the breast are aggressive and grow quickly, most grow slowly. In some cases a tumor may have been growing for as long as 10 years before it creates a lump large enough to feel. That means that even if you know what’s normal for your breasts and notice when something changes, you may not feel anything until the cancer’s been growing for a while.
Screening tests can find breast cancer early, when the chances of survival are highest. They can find breast cancer in a person who doesn’t have any early signs or symptoms. For people at a higher risk, more frequent screening can mean that if they do develop cancer, they can find it and treat it sooner.
The following risk factors (listed alphabetically) have the strongest evidence behind them and are recognized as clearly affecting breast cancer risk, for better or worse.
- Age. Getting older is one of the most important factors increasing the risk of breast cancer. That said, younger women are at risk too. Even women in their 20s can get breast cancer–and black women are more likely to get it at an earlier age compared to white women.
- Age at first period. Women who started having periods before age 12 have a higher risk of breast cancer than those whose periods started after age 14.
- Age at menopause. Women who go through menopause after age 55 have a higher risk of breast cancer than women who go through menopause by age 45.
- Alcohol use. Women who have 2-3 alcoholic drinks per day have a 20 percent higher risk of breast cancer compared to women who don’t drink alcohol.
- Ashkenazi Jewish heritage. Women with Eastern European Jewish ancestry are more likely to have BRCA gene mutations, which put them at a higher risk of breast cancer.
- Biological sex. One of the biggest risk factors for breast cancer is being born female. People born male can get breast cancer, but it’s about 100 times more common in females.
- Breast density on a mammogram. Women who have dense breasts (roughly half of us!) are 4-5 times more likely to get breast cancer. This isn’t about how dense your breasts feel–it’s about how they look on a mammogram. Your doctor can help you figure out your breast density and what screening methods and schedule are best for you.
- Breastfeeding. Women who breastfeed at some point in their lives have a lower risk of breast cancer than those who don’t. The risk is even lower for women who haven’t started menopause and for those who breastfeed for a total of more than 2 years.
- Current or recent use of birth control pills. Using birth control pills slightly increases the risk of breast cancer, but the risk begins to drop when you stop taking the pills and over time returns to that of someone who never took the pill. Susan G. Komen® has more information about birth control and breast cancer risk.
- Current or recent use of menopausal hormones. Menopausal hormone therapy (MHT) used to be common to treat the symptoms of menopause. Today, researchers know that MHT increases the risk of breast cancer, so it’s only recommended in very low doses for short periods of time.
- Exercise. Doing physical activity on a regular basis can lower the risk of breast cancer. It doesn’t have to be intense exercise–even walking and taking the stairs when possible can make a difference. The American Cancer Society recommends 2.5 hours of physical activity a week to lower overall cancer risk.
- Family history of breast, ovarian, or prostate cancer. Women with one or more members of their family (on their mother’s or father’s side) with breast, ovarian or prostate cancer are at a higher risk of breast cancer.
- Having children. Breast cancer risk is slightly lower for women who gave birth to a child by age 35 compared to women who never had children or had their first child after 35.
- Having had a breast condition in the past. Conditions like hyperplasia and lobular carcinoma in situ (LCIS) increase the risk of breast cancer. These conditions would likely be found with a biopsy.
- Having had cancer before. If you’ve ever had cancer, your risk of getting breast cancer is higher. This is true if you’ve had non-invasive cancer (ductal carcinoma in situ, or DCIS), invasive cancer or certain other types of cancer.
- Inherited gene mutations (like BRCA1 or BRCA2). BRCA1/2 mutations greatly increase the risk of breast cancer. How greatly? In a group of 100 women without a mutation, about 7 will get breast cancer by age 70. In a group of 100 women with a BRCA1/2 mutation, 45-65 of them will get breast cancer. Still, BRCA1/2 mutations are rare–about 1 in 400 people in the U.S. have one.
- Radiation exposure at a young age. Women who’ve been exposed to large amounts of radiation, for example through radiation therapy for another type of cancer, are at a higher risk of breast cancer. In general, the more radiation a person is exposed to and the younger they are when they’re exposed, the greater their risk.
- Weight (or weight gain) after menopause. The relationship of weight and breast cancer risk isn’t simple. The most important thing to know about it is that for women who’ve been through menopause, being overweight or obese means a higher risk of breast cancer. Gaining weight over the course of adulthood also increases breast cancer risk.
To see more risk factors, including possible risk factors that are currently under study, visit Susan G. Komen’s website. There are also lots of things that are rumored to increase breast cancer risk but have been shown by research not to. Susan G. Komen has a list of those factors too.
Figuring out your breast cancer risk isn’t simple, so it’s important to work with your doctor to do it. Doctors often use The Breast Cancer Risk Assessment Tool (the Gail model) to estimate risk, but this model may not be the most accurate tool for black women. There are other risk assessment tools out there, so talk to your doctor about which might work best for you.
If you and your doctor determine that you’re at a higher risk of breast cancer, you can decide together on next steps. Routine breast cancer screening is important for all women, but even more so for those at higher risk, so your doctor may suggest you get screened earlier and more often than other women.
You can also talk to your doctor about options for reducing your risk. Depending on your unique situation, your doctor may recommend either of the following:
- Risk-lowering drugs. Tamoxifen and raloxifene are the only drugs FDA-approved for breast cancer risk reduction in women at higher risk. Both are taken in pill form.
- Preventive surgery. For people with certain gene mutations, having surgery to remove their breasts may dramatically reduce their risk of breast cancer. Surgical removal of the ovaries can also reduce the risk of ovarian and possibly breast cancer for certain people.
Everyone’s situation is different, so the most important thing you can do is learn about your risk, then make a plan with your doctor. Bright Pink has more information about partnering with your doctor to reduce your risk.
Knowing your risk of breast cancer is a crucial part of breast health–but it’s not enough on its own. Here’s everything you should know to take charge of your breast health.