The breasts and lymphatic system

This page tells you about the structure of the breasts and about the lymphatic glands.

The breasts

The breasts are made up of

  • Fat
  • Connective tissue
  • Gland tissue divided into lobes

A network of ducts spreads from the lobes towards the nipple.

 Diagram showing the lobes and ducts of a breast

Breast size and density

It is very common for breasts to be different sizes from one another. They may also feel different at different times of the month – for example, just before a period they can feel lumpy.

Breast density changes as a woman ages. Younger women have more glandular tissue in their breasts, which makes them dense. Once a woman goes through menopause, the glandular tissue is gradually replaced by fat, which is less dense. It is more difficult to read a mammogram if the breast tissue is dense so mammograms are not as reliable for younger women.

Specialists have found that older women who take hormone replacement therapy (HRT) have denser breasts than would be expected for their age, which can make their mammograms less accurate.

Because your breasts change over time, it is important to get to know your breasts and what is normal for you at different stages. Learn what your breasts feel like at different stages during your menstrual cycle. Look and feel your breasts in front of a mirror or when you are taking a shower and see if there are changes that are unusual for you. If you do find something unusual, see your GP without delay. Most changes are benign (non-cancerous) but your GP can assess you to be sure.


Lymph nodes and the lymphatic system

Our bodies have a network of lymph vessels and lymph nodes which is part of the body’s immune system. It collects fluid, waste material, and other things such as viruses and bacteria that are in the body tissues, outside the bloodstream.

In the same way that veins collect and carry blood through the body, lymph vessels carry a watery yellow fluid called lymph. Lymph flows through the lymphatic system and eventually drains into veins. This system helps to get rid of waste products from the body.

Diagram showing the network of lymph nodes in and around the breast

Lymph nodes are important in cancer care because any cancer cells that have broken away from a cancerous tumour can be carried by the tissue fluid to the nearest lymph nodes. If your doctors finds a cancerous tumour, they will always examine your lymph nodes to see if there are cancer cells present there. If there are no cancer cells in the nearby lymph glands, your cancer is less likely to have spread. Sometimes lymph nodes become enlarged for other reasons that are not related to cancer e.g. infection.

Your breast tissue extends to under your armpit. The armpits have many lymph nodes, also known as lymph glands. There is also a chain of lymph nodes that runs up the center of your chest, by your breast bone. This is called the internal mammary chain. The diagram shows the network of lymph nodes around the breast.   Because your breast tissue extends to your collar bone and your armpit, it is important to check these areas during your monthly breast self-examination.