comscoreRisk of Triple-Negative Breast Cancer Nearly Three Times Higher for Black Women Than for White Women

Risk of Triple-Negative Breast Cancer Nearly Three Times Higher for Black Women Than for White Women

Black women are 2.7 times more likely to be diagnosed with triple-negative breast cancer than white women, according to a study of risk factors in more than 198,000 women.
Oct 12, 2021.
 

Black women were 2.7 times more likely to be diagnosed with triple-negative breast cancer than white women, according to a study of risk factors in more than 198,000 women.

The research was published in the September 2021 issue of the journal Cancer Medicine. Read “Relationship of established risk factors with breast cancer subtypes.”

 

About triple-negative breast cancer

Triple-negative breast cancer is:

  • estrogen-receptor-negative

  • progesterone-receptor-negative

  • HER2-negative

Triple-negative breast cancers are usually more aggressive, harder to treat, and more likely to come back (recur) than cancers that are hormone-receptor-positive or HER2-positive. Triple-negative breast cancers don’t usually respond to hormonal therapy medicines or medicines that target the HER2 protein.

 

About the study

Hormone-receptor-positive HER2-negative breast cancer is the most common subtype of breast cancer, accounting for about 73% of all cases. Treatments that target the hormone receptors and HER2 receptors have improved outcomes, but there are still large differences in survival between the various subtypes of breast cancer. For example, the 5-year survival rate for hormone-receptor-positive HER2-negative breast cancer is near 95%, but is only about 75% for triple-negative breast cancer.

The researchers who did this study wanted to look at the relationship between the subtype of breast cancer diagnosed and certain breast cancer risk factors.

The study included information from 198,278 women aged 40 to 84 who had a screening mammogram at two hospitals in Massachusetts or through the University of Pennsylvania Health System between 2010 and 2015.

None of the women had been diagnosed with breast cancer when they had their screening mammograms.

Of the women in the study:

  • none had a known BRCA1 or BRCA2 mutation

  • 11% had a previous breast biopsy

  • 0.9% had been previously diagnosed with atypical hyperplasia, a benign breast condition that increases the risk of breast cancer in the future

  • 50.4% were 12 or 13 years old when they had their first period

  • about 40% were between age 20 and 30 when they gave birth to their first child, and 21.3% had never given birth

  • 87.3% had no family history of breast cancer

  • 73.7% were white

  • 15% were Black

  • 11% were Hispanic/Latina, Asian/Pacific Islander, or another race

  • 38.3% had a BMI of less than 25, considered to range from underweight to healthy

  • 24.9% had a BMI of 25 to 29.9, considered overweight

  • 25% had a BMI of more than 30, considered obese

  • 58.2% were postmenopausal

  • 82.5% had a BI-RADS breast density score of B or C; B means the breasts are mostly fatty tissue, but also have scattered dense areas, and C means there are many dense areas

  • 7.9% had a BI-RADS breast density score of D, meaning the breasts are extremely dense

Follow-up time ranged from 4.2 to 9 years.

During follow-up, 4,002 invasive breast cancers were diagnosed in the women in the study:

  • 77.6% were hormone-receptor-positive HER2-negative

  • 7.5% were triple-negative

  • 8.5% were hormone-receptor-positive HER2-positive

  • 3.2% were hormone-receptor-negative HER2-positive

The researchers didn’t have subtype information for about 4% of the breast cancers.

The researchers used statistical analysis to look at links between the risk factors and the subtype of cancer diagnosed.

As the researchers expected, a diagnosis of hormone-receptor-positive HER2-negative breast cancer was associated with well-documented risk factors:

  • older age

  • having a previous breast biopsy

  • having a previous diagnosis of atypical hyperplasia

  • having a family history of breast cancer

  • having a BMI of 25 or greater

  • having a BI-RADS score of B, C, or D

Only four risk factors were associated with a diagnosis of triple-negative breast cancer:

  • older age

  • being Black

  • having a BMI of 25 or greater

  • having a BI-RADS score of B, C, or D

The analysis showed that Black women were 2.7 times more likely to be diagnosed with triple-negative breast cancer than white women. Women with extremely dense breasts — a BI-RADS score of D — were 3.4 times more likely to be diagnosed with triple-negative breast cancer than women with a BI-RADS score of A, which means the breasts are mostly fatty and not dense.

A diagnosis of hormone-receptor-positive HER2-positive breast cancer was associated with three risk factors:

  • having a previous breast biopsy

  • having a previous diagnosis of atypical hyperplasia

  • having a BMI of more than 30

A family history of breast cancer was the only risk factor associated with a diagnosis of hormone-receptor-negative HER2-positive breast cancer.

The researchers then analyzed the interactions between certain risk factors.

The results showed that BMI was a stronger risk factor for certain breast cancer subtypes in postmenopausal women:

  • A BMI of 25 or greater was more strongly associated with a diagnosis of hormone-receptor-positive HER2-negative breast cancer in postmenopausal women than in premenopausal women.

  • A BMI of 25 to 29 was more strongly associated with a diagnosis of triple-negative breast cancer in postmenopausal women than in premenopausal women.

Breast density was a stronger risk factor for certain breast cancer subtypes in premenopausal women:

  • Dense breasts were more strongly associated with a diagnosis of hormone-receptor-positive HER2-negative in premenopausal women than in postmenopausal women.

  • Dense breasts were more strongly associated with a diagnosis of triple-negative breast cancer in premenopausal women than in postmenopausal women; premenopausal women with dense breasts were 2.8 times more likely to be diagnosed with triple-negative breast cancer than premenopausal women with non-dense breasts.

The researchers found that women who had more children had a lower risk of being diagnosed with hormone-receptor-positive HER2-negative breast cancer than women who had fewer children.

Finally, the researchers looked at how frequently certain breast cancer subtypes were found during routine mammograms versus those categorized as interval breast cancers. The National Cancer Institute defines interval breast cancer as a breast cancer that is found between a screening mammogram with normal results and the next screening mammogram. Interval breast cancers tend to be larger and grow and spread more quickly than breast cancers found by a routine mammogram.

Triple-negative breast cancers were 33% less likely to be found during a routine mammogram and more than 2 times more likely to be interval cancers than hormone-receptor-positive HER2-negative breast cancers.

“The risk prediction models available are about 60% accurate for predicting risk of breast cancer,” said lead author Anne Marie McCarthy, Ph.D., assistant professor of epidemiology at the University of Pennsylvania, in a statement. “In our studies, we see clear differences in risk factors across these types of breast cancers, and we need to do a better job of identifying how we can accurately predict risk for women, particularly for women of color.”

 

What this means for you

Every woman has some risk of developing breast cancer. In the United States, the average woman’s risk is about 12%. Still, as this study shows, a number of factors can increase that risk, including getting older, your race, your menopausal status, and your breast density. The study also reinforces the idea that interactions between risk factors, such as BMI and menopausal status, can affect how breast cancer risk is calculated.

If you need to, ask your doctor about risk factors and the best way to estimate your risk.

If you know that you have a higher-than-average risk of breast cancer, you and your doctor can develop a screening plan tailored to your unique situation. General recommended screening guidelines include a:

  • monthly breast self-exam

  • yearly breast exam by your doctor

  • digital mammogram every year starting at age 40

Your personal screening plan also may include a:

  • breast MRI

  • breast ultrasound

Talk to your doctor about developing a specialized program for early detection that meets your individual needs and gives you peace of mind.

It also makes good sense to do all you can to keep your risk of breast cancer as low as it can be. Some lifestyle choices you may want to consider are:

  • maintaining a healthy weight

  • exercising every day

  • limiting or avoiding alcohol

  • eating a healthy diet that’s low in processed foods, sugar, and trans fats

  • not smoking

To learn more, visit Risk and Risk Factors.



— Last updated on February 22, 2022, 9:58 PM

Reviewed by 1 medical adviser
 
Brian Wojciechowski, MD
Crozer Health System, Philadelphia area, PA
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