Breast Density: why knowing your breasts can make a difference in prevention

Not all breasts are the same. And not all mammograms are enough. This awareness—still not widespread enough—is at the heart of one of the most current challenges in breast cancer prevention: breast density, a common but often underestimated factor that affects both cancer risk and the effectiveness of screening tests.

Providing clarity is Dr Giorgio Maria Baratelli, breast surgeon, director of Breast Surgery at the Ospedale di Erba and medical director of the Lega Tumori di Como. He is part of the executive board of the Italian School of Senology and the Accademia di Senologia Umberto Veronesi. «I learned so much from him», he says, referring to Professor Umberto Veronesi. Alongside his clinical work, Baratelli also founded his own academy for medical students, with a parallel path to university studies focused on ethics, behavior, and clinical reasoning.

What is breast density?

Breast density is a physical characteristic of the breast. As Baratelli explains, «Density is a physical characteristic and is the relationship between mass and volume». Applied to the breast, «breast density is the percentage of glandular tissue compared to the fatty tissue that makes up the mammary gland».

In practice, some breasts have a greater fatty component, while others have a greater glandular component. «There are very fatty breasts with a lot of fat, and very glandular breasts with a lot of glandular tissue».

Over time, several classifications have been developed. In the latest version, the breast specialist explains, these include «completely fatty breasts, breasts with scattered fibroglandular densities, heterogeneously dense breasts, and extremely dense breasts».

How breast density is evaluated

Breast density has long been associated almost exclusively with mammography. «The message of mammographic density has spread, but this is a fundamental conceptual mistake», Baratelli emphasises. Density, in fact, «is a characteristic of the breast, which can be studied with mammography, ultrasound, but can also be assessed simply through a clinical examination».

Even without imaging tests, he adds, «by examining a woman, I can tell whether the breast is fatty or glandular». Because of this, «density is a characteristic of the breast studied through various methods».

Age and individual characteristics

Breast density is mainly influenced by age. «Young women have dense breasts; menopausal women usually have less dense breasts». However, this is not an absolute rule. «It is also an individual characteristic. A person is born with blue eyes and dies with blue eyes; she is born with dense breasts, and even during menopause she may still have dense breasts».

A significant fact concerns older women: «About 25% of women over sixty still have dense breasts».

Why breast density matters

Breast density is important for two main reasons. «It is a risk factor for developing cancer», explains Baratelli, specifying that «it is the most important risk factor after age».

The second aspect concerns diagnosis. «The denser the breast, the harder it is to examine». This is especially true with mammography, which is the foundation of screening. «In a fatty breast, the small lump is clearly visible because it is a white opacity on a black background. In a dense breast, we have the same white opacity, but on a white background».

This makes early detection of lesions more difficult.

The limits of standardised screenings

Screening programs are organised as public health tools and are mainly based on age. «The regional computer sends the invitation letter to all women based on just one piece of data: the date of birth». But, Baratelli points out, «women are different, breasts are different».

For this reason, according to the specialist, every woman should have «personalised prevention». A goal that in the future could be made easier through data use. «Artificial intelligence, by cross-referencing data, will be able to provide a better idea of prevention», helping reduce so-called interval cancers—those that appear between one screening and the next.

Informing women about density

In some countries, information about breast density is already required by law. «In 13–15 states in the United States, it is legally mandatory to report breast density on the medical report». In Italy, however, this information is still communicated inconsistently.

Knowing one’s own density is essential also for understanding the limits of tests. «Mammography in dense breasts loses 50%». For this reason, if a woman is aware of her condition, she can better navigate her prevention pathway.

Additional tests

When the breast is dense, mammography alone is not enough. «The simplest and least expensive option is ultrasound». Other methods can be added, such as contrast-enhanced mammography and MRI, which in some cases allow for a more complete evaluation of the breast.

A More personalised and participatory medicine

The issue of breast density fits into a broader vision of modern medicine, which increasingly focuses on personalisation and patient involvement. This approach moves beyond paternalistic medicine and places the person at the center.As Baratelli reminds us, «A good doctor treats the disease, but a truly great doctor treats the person who has the disease».