Breast cancer and the lymphatic system

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.

What is the lymphatic system?

The lymphatic system helps protect us from infection and disease. It is made up of fine tubes called lymphatic vessels. These vessels connect to groups of small lymph nodes throughout the body. The lymphatic system drains lymph fluid from the tissues of the body before returning it to the blood.

Lymph nodes are sometimes called lymph glands. They filter bacteria (germs) and disease from the lymph fluid. When you have an infection, some lymph nodes may swell as they fight the infection.

Breast cancer and lymph nodes

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

The diagram shows the lymph nodes in the breast, shoulders and upper body. They are small, bean-shaped dots, connected by a network of lymph vessels.
Image: The diagram shows the breasts, shoulders and upper body. Lymph nodes and vessels are shown on the right side of the chest. The lymph nodes are small, bean-shaped dots. They are connected by a network of lines, which are the lymph vessels. There are lymph nodes shown at the top of the breast, in the armpit area and in the top part of the chest going up into the neck.

About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Dr Rebecca Roylance, Consultant Medical Oncologist and Professor Mike Dixon, Professor of Surgery and Consultant Breast Surgeon.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 October 2023
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Next review: 01 October 2026
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.