Biopsy

A biopsy is the removal of a tissue sample for examination in a laboratory. It is usually the most important test in the diagnosis of cancer of unknown primary (CUP) because it can show what type of cell has changed. This can point to where in the body the cancer may have started.

Learn more about:

• How a biopsy is done
• Tests on biopsy

How a biopsy is done

For a biopsy, you will usually have a local anaesthetic to numb the area, but in some cases, you may need a general anaesthetic, which makes you unconscious.

There are different ways to remove a biopsy sample. You may have one of the following procedures:

• fine needle aspiration – removes cells using a thin needle
• core biopsy – removes tissue using a wide needle
• incisional biopsy – cuts out only part of a tumour
• excisional biopsy – cuts out the whole tumour.

You might not have a biopsy if the cancer is too hard to reach or if you are too unwell for the procedure.

Tests on the biopsy

If you have a biopsy, the sample will be sent to a laboratory, where a pathologist uses a series of stains on the sample. These stains may show changes in the cells or highlight proteins that are linked to various types of cancer.

In some cases, more specialised tests are done on the biopsy sample. These may include a genomic panel, a series of tests that looks for patterns of abnormalities within the cancer cells. The results may suggest what the primary cancer is most likely to be and which targeted therapy or immunotherapy drugs may be helpful.

This more extensive testing is usually part of research projects and it is not yet clear how useful it is for people with CUP. You can ask your cancer specialists for more information about these specialised tests.

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