The short answer
A relapse, or recurrence, is when cancer returns after a period of not being detected. It can come back near where it started or in a new part of the body.
Recurrence means cancer has come back after it could not be detected.
It happens because a few cancer cells survived earlier treatment.
Local recurrence returns at or near the original site.
Distant recurrence appears in another part of the body.
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The full explanation.
When cancer returns
A relapse — more often called a recurrence — is when cancer comes back after a period during which it could not be detected. Hearing that cancer has returned is frightening, but understanding what it means can help.
Why it happens
Treatment aims to remove or destroy all cancer cells, but sometimes a small number survive. They may be too few to show up on scans or tests. Over time, those remaining cells can grow enough to be found again.
Local, regional, and distant
Doctors describe recurrence by where it appears. Local recurrence returns at or very near the original site. Regional recurrence shows up in nearby lymph nodes or tissue. Distant recurrence appears in another part of the body, which is a form of metastasis.
Still the same cancer
A recurrence is the same type of cancer as the original, even if it appears somewhere new. Breast cancer that returns in the bone is still breast cancer. That is why follow-up care after treatment is designed to watch for the specific cancer a person had.
Words to know
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Common questions
▸What is the difference between relapse and recurrence?
They mean the same thing — cancer returning after a time when it could not be found. 'Recurrence' is the more common medical term.
▸Why does cancer come back?
Sometimes a small number of cancer cells survive treatment and are too few to detect. Over time they can grow enough to be found again.
▸What are the types of recurrence?
Local recurrence returns at the original site, regional recurrence appears in nearby lymph nodes or tissue, and distant recurrence shows up in another part of the body.
▸Is recurrent cancer a new cancer?
No. A cancer that recurs is still the same type as the original — for example, recurrent breast cancer, even if it appears in the bone.
Questions to ask your doctor
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