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Notes on Women's Health
Notes on Women's Health

Are You Dense? The Link between Breast Density and Breast Cancer

The Link between Breast Density and Breast CancerThere are several important breast cancer risk factors among women, such as age, family history of breast cancer and reproductive history, but breast density is one risk factor that has not received extensive attention from the media. In this article, I explain breast density, how to find out if you have dense breasts, and what breast density means for your health.

What Determines Breast Density?

There are three broad categories of soft tissue that make up the female breast: glandular tissue, fibrous tissue, and fatty tissue. Glandular tissue includes the cells that produce milk as well as the milk ducts. Fibrous tissue is connective tissue like ligaments, and fatty tissue is spongy material that fills the regions between glandular and fibrous structures.

Breasts that are called “dense” have more fibrous and glandular tissue than fatty tissue. Typically, younger women and women with small breasts have denser breasts than other women. Since overall breast size is largely determined by the amount of fatty tissue in the breasts and fatty tissue is not dense, women with large breasts are less likely to have dense breasts. However, there is no hard and fast rule for breast density – women of any age with breasts of any size can have dense breasts.

What is the Trouble with Dense Breasts?

Dense breasts can present a problem for breast cancer risk in two ways. First, breasts that are dense can make it difficult for tumor detection by a mammogram. On a mammogram or any x-ray for that matter, dense objects appear white. Tumors also appear white, so dense fibrous connective tissue and glandular tissue may obscure tumors on a mammogram. Conversely, breasts that are mostly fatty tissue do not have many of these obscuring features.

Secondly, dense breasts in and of themselves are a risk factor for breast cancer. However, the American College of Obstetricians and Gynecologists (ACOG) has stated that dense breasts alone are not a major breast cancer risk factor, and you and your OB-GYN should consider breast density as part of your overall breast health.

Your radiologist serves as your primary care provider when it comes to breast imaging approaches. They are the specialist who is best equipped to determine your breast density and make recommendations regarding the need for further imaging beyond mammograms and imaging frequency. Your OB-GYN should receive copies of your breast imaging reports from the radiologist and can help you understand your results if you have further questions. 

How Do You Know if You Have Dense Breasts?

When you begin mammogram screening at age 40 – or sooner in certain cases – the radiologist will provide a standardized report called BI-RADS. Part of this report will contain an assessment of your breast density. It is very likely that your breasts will be at least somewhat dense. Only about 10% of women in the US have breasts that are almost completely fatty. The radiologist will assign your breasts one of four density scores ranging from fatty to extremely dense. According to the American College of Radiology, the BI-RAD report defines four categories of breast composition:

  • Category A – Breasts are almost completely fatty with nothing to obscure possible malignancies.
  • Category B – There are scattered areas of fibroglandular density. These areas are not likely to hide malignancies, but it is possible.
  • Category C – Breasts are heterogeneously dense, which may obscure small masses.
  • Category D – Breasts are extremely dense, which reduces the mammogram’s sensitivity.

Additionally, BI-RADS reports have seven possible major categories for malignancy:

  • Category 0 – Incomplete information. Additional imaging or comparison to old reports are needed.
  • Category 1 – Negative findings, essentially no chance of malignancy
  • Category 2 – Benign findings, essentially no chance of malignancy
  • Category 3 – Probably benign, very little chance of malignancy. Your radiologist may recommend frequent follow-up or surveillance.
  • Category 4 – Suspicious for malignancy. Subcategories 4A through 4C delineate the chance of malignancy, with 4C being the greatest likelihood of malignancy.
  • Category 5 – Highly suggestive of malignancy. This category indicates at least a 95% chance of breast malignancy.
  • Category 6 – Previously known malignancy, proven by biopsy.

Your breast density may change as you age. Your mammogram reports will keep you updated on these changes and also provide a comparison to previous mammograms.

What Do You Need to Do if Your Breasts are Dense?

ACOG advises that dense breasts are not usually a cause for extra measures in women with otherwise average breast cancer risk. However, ultrasound imaging may be an option if you have dense breasts (category C or D above) along with other breast cancer risk factors. Even if you do not have other risk factors, your radiologist may recommend a breast ultrasound if your breast density obscures your mammogram imaging.

Talk with your OB-GYN. They can help you interpret your mammography report and advise you on your options in the event you do have dense breasts. These options may include more frequent screening or supplementary screening methods, like breast ultrasound, according to your specific situation. Click here to schedule an appointment with Dr. John Garofalo, OB-GYN.

What about Self-Exams?

ACOG advocates breast self-awareness regardless of breast density. This concept means knowing the feel and shape of your breasts and taking note of any changes. Whether your breasts are dense or not, they may change over time. Additionally, the presence of a lump or nodule does not necessarily mean you have breast cancer. Several benign conditions, like fibrocystic breasts, can cause these features.

However, you should bring any breast changes to the immediate attention of your OB-GYN. Examples of such changes include lumps, nodules, persistent tenderness, skin thickening or abnormal nipple discharge. Your OB-GYN will investigate the symptoms and determine if more tests are needed.

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About the Connecticut OBGYN Practice

Dr. John Garofalo, M.D., is a CT OBGYN based in Fairfield County, providing care for Norwalk, Darien, New Canaan, Weston, Rowayton and the surrounding areas. He has more than 20 years of practice and surgical experience covering many facets of obstetrics and gynecology.

Laury Berkwitt, APRN, is a nurse practitioner specializing in women’s health in Fairfield County, Connecticut. Women undergoing signs and symptoms of menopause can make an appointment with Laury for Hormone Replacement Therapy. Laury has a passion for providing quality women’s health care in a safe and comfortable manner by creating a trusting patient-practitioner relationship. She has been in practice for more than 10 years, caring for women of all ages.