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Cancer Explained
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Kidney Cancer: Signs and Symptoms

A plain-language guide to the signs of kidney cancer, which often causes no symptoms early on. Based on the National Cancer Institute.

NCI source

Last reviewed: 2026-07-07

The short answer

Kidney cancer often causes no symptoms early and is frequently found by chance on a scan. When symptoms occur, they can include blood in the urine, a lump or ongoing pain in the side, and unexplained weight loss.

  • Kidney cancer often causes no symptoms early and is often found by chance on a scan.

  • Blood in the urine can be a sign.

  • A lump or ongoing pain in the side or lower back can occur.

  • Unexplained weight loss and tiredness can also occur.

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The full explanation.

The simple version

The kidneys filter waste from the blood. Kidney cancer often causes no symptoms early on and is frequently found by chance on a scan done for another reason. When symptoms do appear, blood in the urine is one of the more common ones.

Possible signs

Symptoms, when present, can include:

  • Blood in the urine
  • A lump or ongoing pain in the side or lower back
  • Unexplained weight loss
  • Tiredness or, sometimes, fever

Often found by chance

Because early kidney cancer usually causes no symptoms, many are found incidentally on imaging done for another reason. When found early this way, they are often easier to treat.

Many kidney cancers are found by chance on a scan before causing symptoms.

When to see a doctor

See a doctor for blood in the urine, an ongoing lump or pain in the side, or unexplained weight loss. These symptoms have many other causes but should be evaluated.

Words to know

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Common questions

Does kidney cancer cause early symptoms?

Often not. Many kidney cancers are found by chance on an imaging scan done for another reason, before they cause symptoms.

What symptoms can occur?

Possible signs include blood in the urine, a lump or ongoing pain in the side or lower back, unexplained weight loss, tiredness, and sometimes fever.

Do these symptoms mean cancer?

Usually not. Blood in the urine and back pain have many non-cancer causes. But because they can signal kidney cancer, they should be checked.

When should I see a doctor?

See a doctor for blood in the urine, an ongoing lump or pain in the side, or unexplained weight loss.

Questions to ask your doctor

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Quick quiz

Test your knowledge

0 of 3 answered

  1. Q1.How are many kidney cancers found?
  2. Q2.Which can be a sign?
  3. Q3.Do these symptoms always mean cancer?

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Related learning map

How this explanation connects to 10 other things you can explore — related topics, terms, questions, practice, and its NCI source.

Kidney Cancer: Signs and Symptoms