Cancer Recurrence vs. A New Primary Cancer

This page is for people with a cancer history who have a new finding on a scan. It explains the difference between a recurrence and a new cancer. Your care team decides which one it is.

A new spot turns up on imaging in someone with a cancer history. There are two main explanations. They are not variations of one thing.

A recurrence is cancer that comes back after treatment. NCI says it happens when some cancer cells survive treatment and later grow large enough to find. NCI groups recurrences into three types. Local means in or very near the original site. Regional means in nearby lymph nodes or tissues. Distant means in organs or tissues far from the original site. A recurrence keeps its original name. NCI gives this example: colon cancer may come back in the liver, but it is still called colon cancer.

A second primary cancer is a new cancer in a person with a history of cancer. NCI says this is different from recurrent cancer. ACS describes it as a new cancer that is unrelated to the earlier one.

On a scan report, both can appear as "a new lesion". A scan alone does not say which it is.

NCI says that when cancer may have returned, patients have tests like those done at diagnosis, such as imaging and lab work. NCI also notes that tumor markers are usually combined with other tests, such as biopsies or imaging, and cannot diagnose cancer on their own.

A biopsy is often part of the answer, because the tissue can be studied in a lab. We did not find an approved source that lists which lab tests are used to tell a recurrence from a new primary, so we do not describe them here. Ask your team what was done in your case and why. You can also ask whether your new tissue was compared with your original tumor.

NCI says a recurrence is restaged. This means repeating tests like those done at diagnosis. The new stage gets an "r" prefix, and the original stage stays the same.

A second primary is a separate cancer, so your team plans for it as its own diagnosis. Treatment depends on the type of cancer, its stage and your health. Ask your team how the answer changes your plan and the goal of treatment.

The American Cancer Society groups the causes into three.

The first is previous treatment. Radiation can raise the risk of leukemia, myelodysplastic syndrome and some solid tumors. Chemotherapy drugs called alkylating agents, anthracyclines and topoisomerase II inhibitors can raise the risk of leukemia and myelodysplastic syndrome. ACS says the risk goes up with higher doses and longer treatment.

The second is shared risk factors. Smoking, excess weight, alcohol, poor diet, physical inactivity, UV exposure and HPV infection can raise the risk of more than one cancer.

The third is inherited conditions, such as BRCA1 and BRCA2 changes and Lynch syndrome. If you have had more than one cancer, ask about genetic counseling.

If you notice new or unexplained symptoms after cancer treatment, tell your care team promptly. Do not wait for your next scheduled visit.

• NCI: Recurrent Cancer
• NCI: Cancer Staging
• NCI: Tumor Markers
• American Cancer Society: Second Cancers in Adults