When Do Swollen Lymph Nodes Mean Cancer?

When you have swollen lymph nodes, your first thought shouldn't be, "I have cancer." They're much more likely to be caused by infections or a disease that affects your immune system, and they will often clear up as your body heals.

But sometimes, cancer cells will travel through your bloodstream and end up in your lymph nodes, or even start there.

Your doctor can help you figure out what's causing the changes in your body.

Why Lymph Nodes Swell

There are more than 600 small, kidney bean-shaped lymph nodes in clusters throughout your body -- under your neck, in your armpits and groin, and in the middle of your chest and belly. These store immune cells and act as filters to remove germs, dead and damaged cells, and other waste from your body.


Often, swollen lymph nodes will be close to where the problem is. When you have strep throat, lymph nodes in your neck may swell. Women who have breast cancer may get swollen lymph nodes in their armpit.

When several areas of lymph nodes are swollen, that suggests the problem is throughout your body. It could be something like chickenpox, HIV, or a cancer such as leukemia or lymphoma.

When to See a Doctor

You'll often have a good idea why a lymph node is swollen -- you've got a cold, your tooth is infected, or you have a cut that isn't healing well. If you can't come up with an explanation, it may be time to get checked out.

Lymph nodes that are around 1/2 inch or bigger aren't normal. They shouldn't feel hard or rubbery, and you should be able to move them. The skin over them should not be red, irritated, or warm. And the swelling should go away within a couple of weeks.

Other symptoms are also a reason to make an appointment:


Getting a Diagnosis

Your doctor will probably try to rule out reasons other than cancer first. They'll do a physical exam and ask about things that have happened, like if you've:

  • Been scratched by a cat
  • Been bitten by a tick
  • Eaten undercooked meat
  • Had risky sex or injected street drugs
  • Traveled to certain places or areas

They'll want to know what medications you're taking and other symptoms you have.

Swollen nodes that are close to your collarbone or the lower part of your neck when you're over 40 are more likely to be cancer. On the right side, related to the lungs and esophagus; on the left, organs in your belly. Swollen lymph nodes in your armpit when you don't have a rash or sores on your arm are also suspect.

If your doctor thinks your swollen lymph nodes could be cancer, tests and imaging can confirm the diagnosis or point to something else. Based on where the cancer might be, you could get a chest X-ray, an ultrasound, a CT scan, or an MRI. A scan called FDG-PET, which stands for fluorodeoxyglucose with positron emission tomography, can help find lymphoma and other cancers. And you'll probably get a biopsy. They'll take either a sample of cells from a node, typically using a needle, or remove a whole node. The sample gets sent to a lab so a specialist can check it with a microscope for cancer.

Otherwise, when only a few nodes are involved, you'll usually start with a complete blood count (CBC) to get a picture of your general health as well as more detailed information about your white blood cells, which fight infection. Depending on your other symptoms and your history, your doctor may want additional blood tests or X-rays, too.

If these tests don't show another cause and the swollen nodes don't go away in 3-4 weeks, your doctor will probably do a biopsy. Since the swelling will often go away or another cause will be found while you're waiting to do a biopsy, the delay prevents people from getting procedures they don't need. And even if it is cancer, you should still be able to treat it effectively.

When you have swollen lymph nodes throughout your body, your doctor will ask for a CBC, a chest X-ray, and an HIV test. If these are normal, you might get other tests, perhaps for tuberculosis or syphilis, an antinuclear antibody test (which checks your immune system), or a heterophile test (for the Epstein-Barr virus). The next step is a biopsy of the most abnormal node.


What Does Cancer in a Lymph Node Mean?

Cancer in your lymph nodes may have started there, but it's more often the case that it spread from somewhere else.

Based on the source of the cancer cells and how far away that is from the swollen nodes, your doctor will recommend a treatment plan. It could include surgery, radiation, or chemotherapy, or a combination of treatments.

WebMD Medical Reference Reviewed by Laura J. Martin, MD on August 07, 2018



Insight, Dana-Farber Cancer Institute: "If My Lymph Nodes Are Swollen, Do I Have Cancer?"

Cleveland Clinic: "Swollen Lymph Nodes."

Mayo Clinic: "Swollen lymph nodes."

JAMA Oncology: "Lymph Nodes and Lymphadenopathy in Cancer."

American Cancer Society: "Lymph Nodes and Cancer."

UpToDate: "Evaluation of peripheral lymphadenopathy in adults."

Leukemia & Lymphoma Society: "Imaging Tests," "Blood Tests."

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