The lymphatic system helps to protect us from infection and disease. It also drains lymph fluid from the tissues of the body before returning it to the blood. The lymphatic system is made up of fine tubes called lymphatic vessels that connect to groups of lymph nodes throughout the body.
Lymph nodes (sometimes called lymph glands) are small and bean-shaped. They filter bacteria (germs) and disease from the lymph fluid. When you have an infection, lymph nodes often swell as they fight the infection.
Sometimes, cancer can spread through the lymphatic system. If breast cancer cells spread outside the breast, they are most likely to go to lymph nodes in the armpit.
You will usually have tests to look for cancer cells in the lymph nodes. There are also lymph nodes near the breastbone and above the collarbone.
The lymph nodes near the breast: