The short answer
A fever that has no clear cause and keeps returning can be a sign of some cancers, especially blood cancers like leukemia and lymphoma. Most fevers come from infections, but a persistent, unexplained fever should be checked.
A persistent or recurring fever with no clear cause can be a warning sign of some cancers.
It is more often linked to blood cancers such as leukemia and lymphoma.
Fever can also appear when a cancer has spread.
Most fevers are caused by infections, not cancer.
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The full explanation.
The simple version
Fevers are the body's normal response to fighting infection, and most pass quickly. But a fever that keeps returning or lingers with no clear cause can occasionally be a warning sign of some cancers, and is worth checking.
What it can signal
Fever is more often linked to blood cancers such as leukemia and lymphoma. It can also occur with other cancers, especially if they have spread. Blood cancers can make it harder to fight infections, which themselves cause fevers.
A recurring, unexplained fever is more often linked to blood cancers like leukemia and lymphoma.
Most fevers are infections
The large majority of fevers come from infections — colds, flu, and other illnesses — not cancer. A doctor can help find the cause of a fever that keeps coming back.
When to see a doctor
See a doctor for a fever that keeps returning, lasts more than a few days, or has no clear cause, especially with night sweats, unexplained weight loss, or swollen lymph nodes.
Words to know
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Common questions
▸When is a fever a concern?
Most fevers come from infections and pass quickly. A fever that keeps returning, lasts a long time, or has no clear cause is worth checking, especially with other symptoms.
▸Which cancers cause fever?
Fever is more often linked to blood cancers such as leukemia and lymphoma. It can also occur with other cancers, especially if they have spread.
▸Why does cancer cause fever?
Some cancers affect the immune system or produce substances that raise body temperature. Blood cancers can also make it harder to fight infections, which cause fevers.
▸When should I see a doctor?
See a doctor for a fever that keeps returning, lasts more than a few days, or has no clear cause, especially with night sweats, weight loss, or swollen lymph nodes.
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