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Cancer Explained

Disponible en español: Bultos e hinchazón

Beginner 4 min read Verified

Lumps and Swelling

When a new lump or swelling can be a warning sign of cancer, and when to see a doctor. Based on the National Cancer Institute.

NCI source

Last reviewed: 2026-07-07

The short answer

A new lump or swelling — in the breast, testicle, neck, underarm, or elsewhere — can be a sign of cancer, though most lumps are not cancer. A new or growing lump should be checked by a doctor.

  • A new lump or swelling can be a warning sign of cancer.

  • Most lumps are not cancer, but new or growing ones 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.

Choose how you want to understand this

The full explanation.

The simple version

Finding a new lump can be frightening, but most lumps are not cancer. Still, because some are, a new or growing lump — anywhere on the body — is worth having checked by a doctor.

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 in the neck, armpit, or groin that does not go away
  • Any new lump that is growing or does not resolve

What is more concerning

A lump that is hard, painless, growing, or fixed in place can be more concerning. But you cannot tell for sure by feel, so any new lump should be checked.

You cannot tell by feel whether a lump is cancer — get new lumps checked.

How lumps are evaluated

A doctor may examine the lump and use imaging such as ultrasound or a mammogram, and sometimes a biopsy, to find out what it is. Many lumps turn out to be harmless.

Words to know

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Common questions

Does a lump mean cancer?

Usually not. Most lumps are caused by harmless things like cysts, swollen glands, or fatty growths. 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 use imaging such as ultrasound or a mammogram, and sometimes a biopsy, to find out what it is.

Questions to ask your doctor

Being prepared helps you get the most out of your appointments. Save or print these questions.

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Quick quiz

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0 of 3 answered

  1. Q1.Do most lumps mean cancer?
  2. Q2.Which lump should be checked?
  3. Q3.How might a doctor evaluate a lump?

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Related learning map

How this explanation connects to 11 other things you can explore — related topics, terms, questions, practice, and its NCI source.

Lumps and Swelling