Diagnosing cancer

Tests help diagnose and stage cancer. Find out more about what to expect.


A cancer diagnosis is made only after certain tests are done. Most people begin by visiting their family doctor (GP) because they are worried about a particular symptom. This could be a lump, weight loss or feeling very tired . If your doctor is concerned about you, he or she will refer you to a hospital. There you will see a specialist who may arrange further tests.

At the hospital some tests can be done fairly quickly to check your general health. This includes:

  • A physical exam.
  • Chest X-ray.
  • Blood tests.

Some blood tests can also help to diagnose cancer. The other tests done will depend on which type of cancer is suspected.

Staging cancer

Some tests are done to find (diagnose) cancer, while others are done to stage it. Staging means finding out the size of the cancer and if it has spread to other tissues. Staging helps your doctor to decide on the best treatment for you. Scans like MRI and PET can help to stage a cancer.

Some of the new types of scanning, like PET, may not be available in the hospital in your area. As a result, your doctor may arrange for you to have some tests done in a specialist cancer centre. In Ireland there are eight specialist cancer centres.

Call our National Cancer Helpline

Freephone 1800 200 700 to talk to a specialist cancer nurse
It's open Monday-Thursday from 9am to 7pm and Friday from 9am to 5pm