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

A patient receives a mammogram, which can determine if she has dense breast tissue

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 signed legislation in 2013 that requires radiologists to inform women if dense breast tissue is found on a mammogram. The law is raising awareness among women about this topic.

In an interview, diagnostic radiologist Carol H. Lee discussed the concept of breast density. 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.

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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.

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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.

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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.

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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.

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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, at our Evelyn H. Lauder Breast Center.

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I have recently had mammo, ultra sound, and then MRI and MRI w/contrast. Found several dilated ducts...several benign tumors.....fluid from nipples. And VERY dense breast. They then sent me to have the BRAC test done. It came back negative. I have very large breast 36DD and I will be 35 this May. I am still very worried about breast cancer. If I have a reduction will that decrease my risk?

Tianna, thank you for reaching out. We recommend that you speak with your physician about your concerns as every person’s risk for breast cancer is affected by a large number of factors.

I had my yearly mammogram and it was the same as the year before but my doctor requested I get an ultrasound because of my age and it showed a lymph node in my right axillary and one in my left. One is 12 x 14 x 18 mm and the other is smaller. I actually went and had another ultrasound 2 months later and it is still the same with no changes on the breast or lymph nodes. I do have breast density rated at a #2 and the called it fibroglandular changes . Is this a need for concern?

Dear SAnn, we recommend that you discuss your specific questions and concerns with your doctor, who can better explain what specific changes are being seen on your imaging. You may also be interested in learning more about the breast anatomy, breast density, and symptoms and risk factors for breast cancer here: https://www.mskcc.org/cancer-care/types/breast. Thank you for reaching out to us.

Does lobular cancer show on an ultra sound? If so how early can it be seen?

Pat, thank you for reaching out. Lobular cancer, which makes up about 10% to 15% of all invasive breast cancers, is notoriously hard to pick up with both mammograms and ultrasound because the cancer cells tend to grow in a single file and not make a lump or collect calcifications as often as the more typical type of breast cancer, which is ductal. Invasive lobular cancer is not uncommonly seen on mammograms but does sometimes show up on ultrasound when it is not seen on the mammogram but there is no one answer to how early it can be seen. This varies quite a bit from woman to woman.

I recently have been treated for cancer grade 1 with a lumpectomy and total alnd however I am still tender and sore are there alternatives to a mammogram?

Hi Pauline, this is something that you should discuss with your healthcare team, but we did send your question to Maxine Jochelson, the Director of Radiology at our Breast and Imaging Center, who said that mammogram is the best way to follow someone in this situation. She said that sometimes additional testing may be done, but mammography is the base. Thank you for your comment, and best wishes to you.

If an MRI test comes back indetermine findings due to fibro glandular density is there another imaging besides MRI that can be done? In my case the MRI can not see through the dense tissue.