The tests you need depend on the symptoms you have and which part of your body is affected.
Tests to diagnose rare cancers
To diagnose most cancers, doctors need to take a sample of tissue from the area. They call this a biopsy. A pathologist then looks at the cells in the tissue under a microscope.
For leukaemias and some types of lymphoma, you have blood tests. These might pick up abnormal cells in the blood. You usually also have a lymph node biopsy or a bone marrow test.
If tests show that you have cancer, you usually have some further tests to find out more about the cancer and whether it has spread. These could include scans, such as a CT scan, a PET scan or an MRI scan. Doctors use this information to work out the best treatment for you.
You could have more tests during and after treatment, to see how your treatment is working.
Why it can take longer to diagnose rare cancers
It can take longer for doctors to diagnose a rare type of cancer.
Symptoms might be unusual and less recognisable than more common types. You might also need to have more tests than people with more common cancers.
The tests first work out whether you have a cancer. Then they find out exactly what type it is.
The pathologist might need to do a number of different tests on your biopsy sample or blood test. Or they might need to send the sample to a specialist laboratory for examination. It could take longer to reach a diagnosis if this has to happen.
You might need a specialised test to find out your type of cancer, leukaemia or lymphoma. Depending on the test, it could take quite a few days and sometimes weeks to carry out and get the results.
Getting your test results
Waiting for test results is an anxious time.
While you are waiting it might help to talk to a close friend or relative about how you feel. Or you could contact a cancer support group to talk to someone who has been through a similar experience.