On Cancer: Diagnostic Radiologist Carol Lee Discusses What Women Should Know about Breast Density

By Media Staff  |  Wednesday, January 30, 2013
Pictured: Mammogram A new law requires radiologists to inform women if dense breast tissue is found on a mammogram.

To help improve breast cancer detection and prevention, New York Governor Andrew Cuomo recently signed legislation that requires radiologists to inform women if dense breast tissue is found on a mammogram. The law, which went into effect this month, is raising awareness among women about this topic.

In an interview, we discussed the concept of breast density with diagnostic radiologist Carol H. Lee. Dr. Lee suggests that if you find out you have dense breasts, you should discuss potential next steps with your doctor. Each individual woman’s risk for breast cancer is different, and many factors – such as family history and lifestyle – must be taken into account when determining whether additional forms of breast cancer screening are necessary.

What are dense breasts?

Breasts are made up of different types of tissue: fatty, fibrous, and glandular. Fibrous and glandular tissues appear as white on a mammogram and fatty tissue shows up as dark. If most of the tissue on a mammogram is fibrous and/or glandular, the breasts are considered to be dense.

Because cancer cells also appear as white on a mammogram, it may be harder to identify the disease on a mammogram in women with dense breasts.

How common are dense breasts?

Breast density is classified into one of four categories, ranging from almost entirely fatty (level 1) to extremely dense (level 4). Dense breasts are completely normal. About half of all women have breasts that fall into the dense category (levels 3 and 4). Dense breasts tend to be more common in younger women and in women with smaller breasts, but anyone – regardless of age or breast size – can have dense breasts.

How does a woman know she has dense breasts?

The only way to determine whether a woman has dense breasts is with a mammogram. A breast exam cannot reliably tell whether a breast is dense.

What does having dense breasts do to a woman’s risk for breast cancer?

If you compare the 10 percent of women who have extremely dense breasts with the 10 percent of women who have very little breast density, the risk for breast cancer is higher in those with very dense breasts.

However, most women fall somewhere in between in terms of breast density, so it’s nearly impossible to determine whether a particular woman’s breast density is a risk factor for the disease.

What should women who are told they have dense breasts do?

Women found to have dense breasts should talk to their doctors about their individual risk for breast cancer and together decide whether additional screening makes sense.

Tests such as ultrasound or MRI can pick up some cancers that may be missed on a mammogram, but these methods also have disadvantages. Because they are highly sensitive, they may give a false-positive reading, resulting in the need for additional testing or biopsy that turns out to be unnecessary. There is also no evidence to show that using screening tests other than mammography in women with dense breasts decreases the risk of death from breast cancer.

Ultimately, women who have dense breasts should weigh the pros and cons of additional screening with their doctor.

Should women who do not have dense breasts make any changes to their regular screenings?

Women who do not have dense breasts may still develop breast cancer, and should continue to receive regular mammograms. Regular mammography is the only screening method that has been shown to decrease deaths from breast cancer, and all women of appropriate age should have mammograms, regardless of their breast density.

Memorial Sloan Kettering provides comprehensive, individualized breast cancer screening services that include mammography, ultrasound, and MRI, through our Breast Screening Program, located in Manhattan.


Roselle, we are not able to answer individual medical questions on our blog. We recommend that you speak with your doctor about this. You might also find it useful to call the National Cancer Institute's Cancer Information Service at 800-4CANCER. Thank you for your comment.

My wife had her yearly mammogram and found she had dense tissue is on her breasts. Both her mother and her aunt have also had the same condition. She was sent for another mammogram and it was confirmed that she did have dense cells. She was told that the dense cells were off to the side and not under the nipple where she was told was normal. The recommendation is to remove the dense cell and put in a marker so that follow on xrays can identify where the dense tissue was removed. I did not see any recommendations when searching on-line for information that suggest removing dense tissue nor did I see anything about leaving a marker in her breast. Is this usual or should she ask for additional opinions?

Hi Rick, we are not able to provide individual medical advice on our blog. You might want to call the National Cancer Institute's Cancer Information Service at 800-4CANCER to ask more about this. If your wife would like to make an appointment for a second opinion at MSK, one of you can call 800-525-2225. Thank you for your comment.

I have been having pain in one breast for 2 months, area close to nipple. It's not getting worse or better. Went to my doctor who referred me for a diagnostic mammogram and possibly an ultrasound. They only did a mammogram. When I went back to my doctor for results he said it was normal, with moderate density in both breast. He said there was no need for anything else, just mammogram every 2 years and come back if anything changes. When reading about tissue density should I be concerned about "moderate "density, in combination with pain in only one breast that's not changing? I also had a hysterectomy 2 years ago for complex ovation cysts ( several, odd composition. Not malignant.

Dear Lynn, we are unable to answer personal medical questions on the blog. If you would like to make an appointment with one of our specialists for a second opinion, please call our Physician Referral Service at 800-525-2225. Thank you for reaching out to us.

Is it possible for breast cancer to metastasize to other areas such as bone around your ribs? And could this cause pain in those areas?

Faith, we are not able to provide medical advice or diagnoses on our blog, but in general, yes, it is possible for breast cancer to metastasize to the bone. If you would like to make an appointment to speak with a Memorial Sloan Kettering doctor, you can call 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment for more information. Thank you for your comment.

Would having breast implants make diagnosis of breast cancer in dense breasts more difficult?

Diane, we consulted with Dr. Lee on your question and she responds:

Depending on how much breast tissue is present and where the implants are placed (behind or in front of the chest muscle), the presence of implants can make a mammogram more difficult to read. All women with implants regardless of what type and where they are need at least two extra pictures of each breast in order to see as much breast tissue as possible.

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