Staging

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The importance of lymph nodes in staging breast cancer

Whether the lymph nodes contain cancer cells is an important factor when staging breast cancer, determining treatment, and predicting survival. Though breast cancer has the potential to spread to other regions of the body first, it most commonly spreads first to the axillary (underarm) lymph nodes. This is known as regional spread. From there, the breast cancer can (spread) systematically to other areas of the body (such as the bone, liver, lung, or brain).

If a woman is diagnosed with invasive breast cancer (cancer that has invaded past the wall of the breast duct or lobule and into surrounding breast tissue), it is necessary to examine the axillary lymph nodes to determine whether they contain cancer.

The standard way to examine the lymph nodes is to perform an axillary node dissection. This procedure is often done during the same operation as a lumpectomy or mastectomy and involves removing 10 to 30 lymph nodes for pathological examination under a microscope. The most common side effect of an axillary node dissection is lymphedema (chronic swelling) of the arm, which may affect up to 10% of patients. Lymphedema occurs when the normal process of draining lymph from the arm is disrupted or blocked, causing fluid to build up in the arm.

Another surgical option called a sentinel node biopsy is now being used on select breast cancer patients to determine whether breast cancer is present in the lymph nodes. A sentinel node biopsy involves removing only one to three sentinel lymph nodes (the first nodes in the lymphatic chain).

Studies continue to show that removing fewer lymph nodes may decrease the chance of developing lymphedema, though research on sentinel node biopsy is ongoing. The degree to which sentinel node biopsy is effective in determining whether the lymph nodes contain cancer has been shown in research to be directly related to the experience of the surgeon who is performing the procedure. If the sentinel node(s) is found to be cancerous upon removal, a complete axillary node dissection is usually performed.

Good to know!

It is important to remember that even if your doctor tells you that a biopsy is needed, most women who do it do not have breast cancer. In the US, about 1 in 10 women who have biopsies are diagnosed with cancer.