Your doctor may want to do a number of tests in order to try to identify the primary cancer. Exactly which tests you will be asked to have will depend on the clues the doctor has already picked up – for example, the symptoms you have had, your medical history, and where your secondary cancer is.
Unfortunately, it is not possible to describe here all the possible tests that you may be asked to consider. Your doctor, however, should describe to you the purpose of each test.
Tests will probably include an x-ray and a CT scan, blood tests, urine tests and a biopsy (the removal of a small sample of the secondary tumour for examination in the laboratory).
Although it can sometimes be helpful, there is often no real benefit in finding out where the primary cancer started. Your doctors will carefully choose only those tests they feel are absolutely necessary, rather than put you through lots of investigations and tests that may take time and be very tiring, but not make a difference to your overall care.
Information can help to reduce your frustration. Ask your doctor or the other staff looking after you to explain what the tests you are having involve, why they are being done, and what the results mean. If you don't understand their explanation at first, ask again. You may find it helpful to write down the questions you want to ask.