What to Expect: Checking Lymph Nodes

Eileen Bailey Health Guide
  • Skin cancer, and other types of cancer, can spread to lymph nodes, starting with lymph nodes closest to the cancer site. When cancer is diagnosed, your doctor may want to have further testing done to find out if the lymph nodes are involved, and, if so, how extensively.

    The Lymphatic System

    Our body has a system of lymph nodes located throughout the body. These nodes are connected by lymphatic vessels. The vessels carry oxygen and nutrients to other cells and tissues in the body. The fluid produced by the lymph nodes also contain white blood cells to help us fight infection. As the fluid goes through our body and “feeds” cells, it also collects carbon dioxide and other waste from the cells, filters it and then releases it back into the bloodstream.

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    Sometimes, cancer cells break away from the main, or primary, tumor and end up in the lymphatic system and may settle in a lymph node. The lymph node works to filter out waste and kill the cancer cells, but is not always successful and the cancer can grow in or around the lymph nodes.

    Because cancer cells can spread to other parts of your body through the lymphatic system, it is important for doctors to determine if cancer has spread to the lymph nodes and treat it as quickly as possible.

    Testing for Lymph Node Involvement

    When cancer has reached the lymph nodes, they can become enlarged, although this also happens if you have some type of infection. Your doctor may order some initial tests to help determine if the lymph nodes are involved.

    CT Scan

    A computerized tomography scan (CT) is a series of x-rays that build a 3-D image of the lymph nodes. You may be given a drink or injection of a dye to help the technicians see a certain area of your body.  It usually takes 10 to 15 minutes to complete.


    An MRI, magnetic resonance imaging, scan uses magnetism to build a picture of the lymph nodes (or whatever area your doctor wants to see). With an MRI, as with a CT scan, you may be given a dye to help make the images clearer. During an MRI you lie very still in a cylinder. It is not painful but can be uncomfortable to lie still for the length of the test - usually around 30 minutes. Some people feel claustrophobic in the cylinder.

    PET scan

    A PET scan, positron emission tomography, measures the activity of cells - cancer cells are usually more active than healthy cells. A small amount of radioactive substance is injected into a vein. A few hour later, the scan is completed.

    These types of scans show whether lymph nodes are enlarged or if cancer is present. However, the results of the tests may be inconclusive or your doctor may want further testing.


    A biopsy is when a part of tissue is removed and examined under a microscope to detect the presence of cancer cells. There are a few ways a biopsy is completed:

    Excision biopsy - Your doctor will remove one or more lymph nodes. This is done while you are under a general anaesthetic.

    Needle biopsy - A needle is inserted into the lymph node and cells are removed.

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    Sentinel lymph node biopsy - When your doctor performs surgery to remove a tumor, he injects a small amount of radioactive substance in the area of the cancer. The lymph nodes that turn blue first are those lymph nodes that are feeding the area of your body where the tumor is located - the sentinel nodes. The doctor removes only those nodes.

    Based on the results of scans and/or biopsies, your doctor determines whether cancer has spread to the lymph nodes and, if so, how extensive your cancer is. Based on this information, he will create a treatment plan.


    “Lymph Nodes and Cancer,” Reviewed 2011, Sept 15, Staff Writer, American Cancer SOciety

    “Secondary Cancer in the Lymph Nodes,” Reviewed 2013, Jan. 1, Staff Writer, Macmillan Cancer Support

Published On: October 17, 2013