What is the difference between breast density, breast size and breast firmness?

For the general public, it is common to confuse breast density with breast size. There is a tendency to believe that the bigger something is, the denser it is. This is not true. Breast density and breast size are two completely different concepts.

Breast size is usually expressed in terms of cup size. This is obtained by comparing your breast size with your underbust size. For example, a difference of about 17 cm corresponds to a C cup.

Breast density has nothing to do with this physical criterion. It cannot be seen with the naked eye or by feeling the breast. Only an X-ray examination such as a mammogram can determine breast density. It is related to the concentration of connective tissue in the breast.

Similarly, the firmness of the breasts is not a factor in determining whether they are dense or not. A firm breast is not necessarily dense and vice versa. The firmness of the breasts is due to the elasticity of the skin. If the skin becomes slack, the breasts will become less firm. But this does not affect breast density.

Breast density is a physiological, not a physical characteristic

The breasts are made up of different tissues: glandular, connective or fatty (also called adipose tissue). These tissues do not react in the same way to the X-rays emitted during mammography. The mammary glands and connective tissue will appear white on the X-ray, while the fat will be black.

A dense breast is a breast that has a high concentration of connective tissue in relation to fatty tissue. As a result, the mammogram result will show large white areas. This is how you can tell whether a woman has dense breasts or not.

Radiologists use the BI-RADS classification to classify breast density into 4 categories from A (least dense) to D (most dense). The more fatty tissue a breast contains, the lower the breast density. This explains the fact that high breast density is often found in thin women, as shown in a study published on 12 September 2014 by the Journal of the National Cancer Institute. They have less fatty tissue in the breast.

A Breasts almost entirely fatty <25% B Breasts with areas of density
B Breasts composed of scattered areas of fibroglandular density. 25 to 50% approximately
C Heterogeneously dense breasts, which may mask small masses. 51-75% approx.
D Extremely dense breasts, reducing the sensitivity of mammography. >75%

The majority of women have breast density category B (heterogeneous fatty breasts) or C (heterogeneous dense breasts). The term heterogeneous is used to indicate the presence of other tissues in smaller amounts. Breast density category D refers to homogeneous dense breasts (very little fatty tissue present). This accounts for approximately 5-10% of women over the age of 50.

The incidence of dense breasts in breast cancer
Breast X-ray ©Adobe

Breast density is an important factor to consider as it has a real impact on breast cancer detection. High breast density both confers a higher risk of developing breast cancer and makes mammography more difficult to read

Mammography is the primary means of screening for breast cancer. This X-ray examination reveals any abnormalities that may be tumours. These will appear in white on the mammogram.

In the case of high breast density, it will be difficult to distinguish a white spot among the many white areas representing connective tissue.

Breast density decreases the sensitivity of mammography, which is no longer sufficient as a preventive examination. Other screening tools should be considered: ultrasound, etc.

Breast density, volume and firmness: what you need to remember

Breast size is a physical characteristic that relates to the size of the breast. Breast firmness is related to the elasticity of the skin. Both are palpable and visible to the naked eye.

In contrast, breast density is an invisible factor. It can only be established following a mammogram, which will show the proportion of connective and glandular tissue in relation to fatty tissue. The more connective and glandular tissue there is, the denser the breasts will be.

Neither the volume nor the firmness of the breasts has any influence on breast density.

Breast density is an important factor to consider when assessing the risk of breast cancer and tailoring screening tests. Whatever your breasts, firm, dense, small or large, be proud of them, protect them!