Knowing your risk level dictates how often you’re screened or even treated for breast cancer.

As of now, there is no guaranteed way to prevent breast cancer. Certain lifestyle habits can lower your breast cancer risk, but most of the time, there’s no clear reason why breast cancer develops. (Even genetic causes of breast cancer occur in fewer  than 10 percent of cases, according to the American Cancer Society.)

That said, doctors do classify women into different risk groups (average, moderate, and high) to help determine how often they should be screened for breast cancer with mammograms or other imaging tests.

Factors for Average Breast Cancer Risk

You may fall into an average-risk level of breast cancer if you fit the following criteria:

• Have no family history of breast cancer

• Have no personal history of breast cancer

• Are not a gene carrier

• Have not previously had radiation to the chest

In many cases, women who have an average risk of breast cancer should begin screening between ages 40 and 49—although that’s ultimately a decision between you and your doctor. “Health care professionals will usually speak with women about the pros and cons of screening at that age,” says Brenda Panzera, MD, an oncologist at Lenox Hill and Mount Sinai Hospitals in New York City.  

For women ages 50 to 74, doctors recommend screening for breast cancer with mammograms every one to two years. That’s because most breast cancer diagnoses occur in women over age 50, according to the Centers for Disease Control and Prevention. 

“After the age of 75, the recommendations for screening depend on that individual’s life expectancy,” says Dr. Panzera.

Factors for Moderate Breast Cancer Risk

You may have a moderate risk of breast cancer if you fit the following criteria:

• Have not previously had breast cancer

• Have a family member with breast cancer (especially a first-degree family member) but do not carry breast cancer genes

“The recommendations for screening for a moderate-risk individual are the same as an average-risk individual,” says Dr. Panzera, “and that needs to be very carefully individualized for each person.”

Factors for a High Breast Cancer Risk

You are considered to be at high risk of breast cancer if you fit the following criteria:

• Have previously had breast cancer

• Have a first-degree relative with breast cancer who carries breast cancer genes

• Are personally a gene carrier

• Have had chest radiation between the ages of 10 and 30 (such as for Hodgkin’s disease)

“Breast cancer screening for high-risk individuals should [begin] with mammograms annually,” says Dr. Panzera. Additionally, doctors may also use ultrasounds and MRIs.

The age that those annual screenings should begin depends on the individual’s specific risk factors. “For individuals who have a family member who was a gene carrier, we will often start screening at least 10 years prior to the diagnosis of the individual who had previously been diagnosed,” explains Dr. Panzera.

Should You Start Screening for Breast Cancer?

If you’re unsure, ask your doctor about the right age and frequency to start breast cancer screening. Even though doctors have general guidelines for when screening should begin, these decisions are always individualized depending on your personal situation.