Know Your Breast Cancer Risk
Everyone has some risk of developing breast cancer. An individual’s risk may be higher or lower, depending on specific risk factors.
It’s a good idea to find out your personal risk of breast cancer as early as possible so that you and your doctor can develop a breast cancer screening strategy that makes sense for your individual situation.
The American College of Radiology recommends that all women, but especially Black women and women of Ashkenazi Jewish descent, be evaluated by a doctor to find out if they’re at higher-than-average risk for breast cancer no later than age 25.
Determining your breast cancer risk
Medical guidelines categorize breast cancer risk levels based on your lifetime risk of developing breast cancer.
Average risk is less than 15%.
Intermediate risk is 15% to 19%.
High risk is 20% or greater.
The best, and often easiest, way to find out whether you’re at average, intermediate, or high risk for breast cancer is to ask your primary care doctor or gynecologist to do a risk assessment. Another option is getting a risk assessment at a breast clinic or genetics clinic.
Your healthcare provider may suggest that you get genetic testing if you haven’t done so already and you have certain risk factors such as a family history of breast cancer.
You might choose to use online breast cancer risk calculators to learn about your risk, but those aren’t a substitute for getting a comprehensive risk assessment by a healthcare provider. Also, you should always ask your provider to help you interpret your results from an online risk calculator.
Your breast cancer risk may be higher than average if:
you have mutations (changes) in certain genes that increase your lifetime risk of breast cancer, such as a BRCA1 or BRCA2 mutation
you have a first-degree relative (parent, sibling, or child) who was found to have a gene mutation linked to a higher risk of breast cancer, but you have not had genetic testing yet
you have a family history of breast cancer, meaning that one or more of your close relatives have had breast cancer. The risk is higher if a relative developed breast cancer before the age of 50
you had radiation therapy to your chest before the age of 30
you've been diagnosed with certain non-cancerous breast conditions that can increase the risk of breast cancer, such as lobular carcinoma in situ (LCIS), atypical lobular hyperplasia (ALH), or atypical ductal hyperplasia (ADH)
There are many other breast cancer risk factors — some of which raise your risk more than others, and some of which you have the power to change. Also, some of the risk factors for breast cancer have yet to be discovered.
Risk and breast cancer screening recommendations
Your healthcare provider should take into account your personal risk for breast cancer and medical history when making recommendations about when you should start getting mammograms or other types of breast imaging to screen for breast cancer and how often to get them.
Before talking with your provider about your screening plan, you might want to read up on the latest mammogram screening guidelines published by various medical organizations.
If a mammogram shows you have dense breast tissue, your provider may recommend you get a breast MRI or ultrasound in addition to routine mammograms. This is because dense breasts may make it harder for doctors to see breast cancer on mammograms. Also, having dense breast tissue slightly raises your risk of developing breast cancer. Adding other breast imaging (supplemental screening) to mammograms may lower the risk that cancer will be missed.
Lowering your risk
Some breast cancer risk factors can’t be changed, such as your genetics or family history. But there are lifestyle choices you can make, like quitting smoking and exercising regularly, that can potentially lower your risk of breast cancer.
People who have a much higher-than-average risk of breast cancer (for example, people with BRCA1 and BRCA2 gene mutations) can consider risk-reducing strategies. These strategies might include, for example, getting a prophylactic (preventive) mastectomy or taking hormonal therapy.
Talk with your provider about the steps you can take to keep your individual risk of breast cancer as low as possible.
Absolute risk and relative risk
When talking with your health care team or reading about breast cancer risk, you may come across the terms absolute risk and relative risk.
Absolute risk refers to a person’s risk of developing a disease, such as breast cancer, over a defined period of time. For example, the National Cancer Institute is referring to absolute risk when it reports that the average U.S. woman has about a 1 in 8 chance of developing breast cancer in her lifetime.
Relative risk compares risk in two different groups of people. Relative risk also shows how someone’s behavior can change their risk compared with their absolute risk.
For example, a 2017 study found that women who started smoking before age 17 had a 24% higher risk of developing breast cancer. This 24% increase in risk is relative risk. It doesn’t mean that women who start smoking before age 17 have a 24% risk of developing breast cancer in their lifetime. It means the risk is 24% higher than the average risk of 12.9%.
To figure out the increase in absolute risk, we have to do some math: 24% of 12.9% is 3% (.24 × .129 = .03). So a woman who starts smoking before age 17 has a 3% increase in absolute risk, which means her lifetime risk of developing breast cancer is 15.9% (12.9% + 3%).
Relative risk can be confusing because many people focus on the increase in risk and assume it’s an increase in absolute risk.
An increase of 24% sounds alarming. But it’s important to remember that this increase is relative to the average risk of developing breast cancer.
Breast cancer risk can also decrease.
For example, a 2019 study found that women who did at least 2.7 hours of moderate exercise a week, such as walking, or 1.5 hours a week of strenuous exercise, such as running, were 20% less likely to develop breast cancer than women who exercised less than those amounts. This 20% decrease in risk is relative risk. It means the risk of developing breast cancer is 20% lower than the average risk of 12.9%.
To figure out the decrease in absolute risk, we have to do math again: 20% of 12.9% is 2.6% (.2 × .129 = .026). So a woman who does 2.7 hours of moderate exercise a week or 1.5 hours of strenuous exercise a week has a 2.6% decrease in absolute risk, which means her lifetime risk of developing breast cancer is 10.3% (12.9% - 2.6%).
— Last updated on November 30, 2024 at 8:50 PM