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I have dense breast tissue…but what does it mean?

A popular topic in the latest breast cancer research has been the relation between dense breast tissue and the increased risk to develop breast cancer, 5-10% to be exact. Many women are told during a mammogram examination that they have dense breast tissue and are at a higher risk, but what exactly does that mean?

On a mammogram, breast tissue is depicted as varying shades of grey. The appearance

of the breast tissue amongst women varies and is also seen as variations in the

composition on a mammogram. Fatty tissue is dark grey and known as lucent (seethrough).

Connective and epithelial tissue (the glandular part of your breast) is white and

known as dense.

When your doctor is referring to your ‘dense’ breast tissue, on a mammogram report,

they’re referring to the glandular (white) component seen on the image. The denser the

breast tissue, more white components are seen, and because it is so dense, it is difficult

to ‘see through it’.

Cancerous solid tumors in the breast sometimes also appear as white star-shaped

nodules, and micro-calcification (small white groups of specks) are also depicted as white

on a mammogram, so in-between all your dense breast tissue, there may be similar

dense white abnormalities hiding in-between the breast tissue, thus making it hard to

visualise the cancer. From a radiological point of view, the sensitivity rate of detecting

breast cancer in a dense breast can reduce from 97-98% to 85-87%.

Younger women have naturally denser breast tissue. This is normal and expected for their

age group, and as a woman ages, the glandular dense tissue will gradually involute

(change) to a fattier type consistency. This, however, is not true for women who are on

hormone replacement therapy (HRT) as this can cause the density of the breast to remain

the same as women age.

There are five types of breast tissue:

Type I: Most common type of breast tissue in pre-menopausal women.

Type II: Fatty type breast tissue.

Type III: Like Type II, the breast is fatty, but has a few visible ducts on the mammogram.

Type IV: See nodules and densities (moderate dense type breast tissue).

Type V: Dense breast tissue.

Normally, most women over 40 years have a common Type II breast tissue. In women

over 50 years, Type V breast tissue is less common. The prevalence (how many is seen

in a group) of breast cancer in women with Type IV-V breast tissue is more than women

with Type I-III breast tissue.

Meet our expert - Kathryn Malherbe

Kathryn Malherbe is a senior mammographer working at LaVita Women’s Wellness Centre in Pretoria.

She is currently working on her Master’s degree, which focuses on lobular carcinoma of the breast, and the diagnosis thereof can be improved with

ultrasound detection tools.

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