The short answer
A new lump or swelling — in the breast, testicle, neck, underarm, or elsewhere — can be a sign of cancer. NCI says symptoms like this are most often caused by other problems. A new or growing lump should still be checked by a doctor.
A new lump or swelling can be a warning sign of cancer.
NCI says symptoms like these are most often caused by illness, injury, benign tumors, or other problems, but new or growing lumps should be checked.
Lumps in the breast, testicle, or a swollen lymph node are common examples to get evaluated.
A hard, painless lump that is growing is more concerning, but any type should be checked.
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The whole article, with every detail and caution.
This page is for anyone who has found a new lump or swelling. It covers which swellings need help right away, which lumps to get checked, and how doctors check them.
The simple version
Finding a new lump can be frightening. NCI says symptoms like this are most often caused by other problems. But some lumps are cancer, so a new or growing lump anywhere on the body is worth having checked by a doctor.
When to get help sooner
Most lumps can wait for a routine appointment. A few patterns of swelling cannot.
- Call 911 or go to an emergency department if a neck or throat swelling makes it hard to breathe or swallow, or your breathing is noisy and you are drooling. Do not drive yourself.
- Call 911 or go to an emergency department if one leg or arm is swollen, painful, warm, or discolored. This is more urgent if you are also short of breath or have chest pain. Do not drive yourself.
- Call 911 or go to an emergency department if your face, neck, and both arms are swelling, with shortness of breath and veins standing out on your chest, and it is worse lying flat. Do not drive yourself.
- Call 911 or go to an emergency department if a swelling is red, hot, and spreading fast, with a fever, confusion, or very fast breathing. Do not drive yourself.
- Call your care team the same day if a lump is growing over days, feels hard, or does not move under the skin.
- Call your care team the same day if a lump comes with night sweats, a fever, or weight loss you cannot explain. If you are on chemotherapy, a fever needs a call right away, day or night.
- Call your care team right away, day or night, if you are on chemotherapy or have low white blood cell counts and you have a temperature of 100.4°F (38°C) or higher, chills, a sore throat, mouth sores, burning when you urinate, or redness where a catheter enters your body. A normal temperature is not a reason to wait. CDC says to call your doctor immediately for a fever during chemotherapy. If you cannot reach your team, go to the nearest emergency department.
- Call your care team within a day or two if a swollen node is red and tender, or has not shrunk after several weeks.
A lump that changes week to week is worth an early appointment.
Lumps worth checking
Common examples to get evaluated include:
- A new lump in the breast or underarm.
- A lump or swelling in a testicle.
- A swollen lymph node (a small bean-shaped gland of the immune system) in the neck, armpit, or groin that does not go away.
- Any new lump that is growing or does not go away.
What is more concerning
A lump that is hard, painless, growing, or fixed in place can be more concerning. So can a node that is red and tender, or one that keeps getting bigger.
You cannot tell by feel whether a lump is cancer. Get new lumps checked.
How lumps are evaluated
A doctor may examine the lump. They may order blood tests or imaging (scans). For a breast lump this may be a mammogram. For a swollen node it may be a chest X-ray or CT scan. Sometimes a biopsy is needed to find out what the lump is. Many lumps are not cancer.
Sources
Common questions
Does a lump mean cancer?
Often not. NCI says symptoms like these are most often caused by illness, injury, benign tumors, or other problems. MedlinePlus says infections are the most common cause of swollen lymph nodes. But because some lumps are cancer, a new or growing lump should be checked.
Which lumps should I get checked?
Get any new lump checked, especially in the breast, a testicle, or a lymph node area like the neck, underarm, or groin. Swelling that does not go away should also be evaluated.
What makes a lump more concerning?
A lump that is hard, painless, growing, or fixed in place is more concerning, but you cannot tell for sure by feel — any new lump should be checked by a doctor.
How is a lump evaluated?
A doctor may examine it and order blood tests or imaging, such as a mammogram for a breast lump or a chest X-ray or CT scan for a swollen node. Sometimes a biopsy is needed to find out what it is.
Questions to ask your doctor
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Get urgent help
Fever of 100.4°F (38°C) or higher during chemo, severe pain, or trouble breathing: call your cancer care team right away, day or night. Call 911 for an emergency.
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Last updated: 2026-09-29Next planned review: 2027-07-07
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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