Understanding Breast Cancer Risk

Despite being one of the most common types of cancers, the scientific explanation for why breast cancer occurs more often than other types of cancers is unknown in the medical community. 

What researchers do know is which factors heighten – or lower – the risk of developing breast cancer. As breast cancer prevalence grows (women have a 13 percent lifetime risk, meaning 1 in 8 women will be diagnosed), having a basic understanding of what puts you at risk can help you prepare for the future. 

In this blog, we speak with Nicole Sharp Cottrell, M.D., FACS, a fellowship-trained breast surgical oncologist at INTEGRIS Health, who encourages patients to understand their risk assessment.

“I encourage patients to visit us at INTEGRIS Health’s High-Risk Breast Clinic, located within our INTEGRIS Health Breast Surgery Clinic, where they will receive counseling on risk-reducing medical and surgical treatments as well as potentially qualify for supplemental breast imaging, like breast MRIs, that may detect breast cancer at an earlier, more treatable stage.”

Breast cancer risk factors

Age and gender are the most significant risk factors in developing breast cancer, but there are other controllable and uncontrollable components that play a role.

Controllable risk factors

• Lack of physical activity: The exact reasons aren’t known, but women who sit for long periods of time and don't exercise are at a higher risk.
• Overweight/obesity: In general, overweight or obese women are at a higher risk for hormone positive breast cancer, but this is also more prevalent among menopausal women. Excess fat tissue produces more estrogen, which can help provide fuel for cancerous cells.
• Hormone therapy: During menopause, some women receive hormone replacement therapy (HRT) to boost estrogen and progesterone levels. While there are some proven benefits from hormone therapy, there is an increased risk of hormone positive breast cancer the longer the therapy is taken.
• Reproductive history: Certain factors such as not having children and having children later in life (after 30) or not breastfeeding can increase breast cancer risk. Having children and breastfeeding lowers estrogen levels, so the idea is women who have children late or don’t have them at all are exposed to higher levels of estrogen for a longer period.
• Alcohol consumption: Consuming just one drink a day increases your risk by up to 10 percent, while two to three drinks a day can increase your breast cancer risk by 20 percent.
• Environmental exposure: People who work in industries that are exposed to toxic chemicals such as benzenes, pesticides and formaldehyde have an increased risk of cancer.

Uncontrollable risk factors

• Age: Most women with breast cancer are diagnosed after the age of 50.
• Gender: Breast cancer is about 100 times more common in women than men.
• Genetics: Genetic changes, such as alterations to the BRCA1 and BRCA2 genes, carry a higher risk of breast cancer.
• Menstrual history: Women who have an early menstrual cycle (before 12) or who develop menopause later (after 55) are more at risk. This is due to longer exposure to hormones, including estrogen.
• Breast tissue composition: Some women have dense breast tissue, meaning they have more connective tissue than fatty tissue. Women with dense breasts are four to five times more likely to develop breast cancer. Dense breast tissue also makes it harder to detect cancer on an X-ray of the breast called a mammogram.
• History of breast cancer or other breast diseases: Women with a previous breast cancer diagnosis are more likely to develop it in the future. Certain benign breast diseases, such as atypia of the breast and lobular carcinoma in situ (LCIS), also carry an increased risk.
• Family history: Women with a family history of breast cancer are two to three times more likely to also have breast cancer. Family history, i.e., male and female relatives that are first degree (parents, siblings, children) or second degree (aunts, uncles, grandparents, half siblings, nieces and nephews) are important to estimate cancer risk.
• Radiation therapy: Radiation before the age of 30 to treat cancer in the head, neck, chest or breasts will also increase your risk. For example, people with Hodgkin’s lymphoma who receive radiation between the ages of 10 and 30 are more at risk of developing breast cancer later in life.

Is breast cancer genetic?

Yes, some breast cancers are found to have a genetic factor. In fact, family history and inherited genetic changes categorically put women at a high risk for breast cancer. Greater than 60 percent of women with mutations to the BRCA1 or BRCA2 genes will develop breast cancer by the age of 70. 

Normally, the BRCA genes – BRCA 1 is located on chromosome 17 and BRCA2 is located on chromosome 13 – help suppress tumors by repairing damaged DNA. But some people are born with variations to these genes, which takes away their ability to repair cells and can allow cancerous cells to form.

However, it’s important to know that having a genetic mutation doesn’t mean you’ll have breast cancer at some point. Instead, it simply increases your risk of developing breast cancer. For example, only 5 to 10 percent of breast cancer diagnoses come from genetic mutations.

The following is a list of the most common gene mutations that can lead to breast cancer:

• BRCA1
• BRCA2
• p53
• CHEK2
• ATM
• PALB2

In addition, current high-risk gene panels run at INTEGRIS Health also include the following genes: 

• TP53
• PTEN
• STK11
• CDH1
• RAD51C
• RAD51D
• NTHL1
• BARD 1

How to lower breast cancer risk

The Tyrer-Cuzick Risk Assessment, also known as the IBIS tool, is a model used to estimate the risk of developing breast cancer. It takes into account a comprehensive set of variables, including personal and family medical history, genetic factors and other risk factors like age and reproductive history. This tool helps identify people at higher risk, allowing for more personalized screening and prevention strategies.

If you fall into a high-risk category, your doctor may suggest medications or surgery to reduce your risk. 

In general, though, changing controllable behaviors is also encouraged as an additional method to lower the chance of developing breast cancer.

Limit alcohol and tobacco: If you consume two or three alcoholic beverages a night, reducing your intake to a nightly drink or only once or twice a week can lower your risk. Tobacco cessation can also significantly lower your risk, which also includes vaping.

Medications: There are two types of medication classifications used to reduce the risk – selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs). SERMs bind to estrogen receptors and prevent breast cancer cells from multiplying, while AIs work by blocking the enzyme aromatase that is responsible for converting other hormones into estrogen. Hormone positive cancer cells need hormones to grow, so reducing estrogen slows or stops the growth. Tamoxifen and raloxifene (both SERMs) are two of the most common types of preventive medications used to lower breast cancer risk. They’re taken daily for five years. It’s important to note these medications don’t decrease the risk of triple negative breast cancer.

Surgery: Some women may undergo a prophylactic mastectomy (surgery to remove one or both breasts) or a prophylactic salpingo-oophorectomy (surgery to remove the ovaries and tubes). These surgeries do not completely eliminate the risk of developing the disease so they should be considered risk reducing. These surgeries can lower the risk by more than 90 percent. This risk reduction is seen in men and in women who have contralateral mastectomies in the absence of a gene mutation. 

INTEGRIS Health strives to make it easy for patients to understand their breast cancer risk. According to Cottrell, “INTEGRIS Health Comprehensive Breast Center publishes each patient's risk calculations on the bottom of their mammogram, so that this information is readily available to patients and their providers.” 

The earlier breast cancer is found, the better the prognosis. Contact your doctor if you have a family history of breast cancer and think you should receive genetic testing. You should also ask your doctor how often you should receive an X-ray of the breast, also called a mammogram. To schedule your mammogram, call 1-855-MY-MAMMO (1-855-696-2666).