How cancer is diagnosed

Usually your doctor will refer you for tests to find out what is causing a particular symptom.

The tests will depend on which type of cancer is suspected. Common tests to diagnose cancer are:

  • Scans, such as MRI scans, X-rays and ultrasound scans: These can sometimes show a mass inside your body, which could be a tumour.
  • Scopes: Scopes are tubes put into your body with a light and a camera on the end. Scopes let your doctor see inside your body and check for any abnormal changes. They can also take samples of tissue from your body using a scope with instruments on the end.
  • Blood tests: These can help to diagnose some cancers. For example, they can detect substances called tumour markers which may be caused by cancer.
  • Biopsies: A biopsy is a sample of tissue taken from your skin or inside your body. The sample is then examined under a microscope to see if there are any cancer cells. A biopsy is usually needed to make a definite diagnosis of cancer.

We have lots of information about each type of cancer test. 

Read more about cancer tests 

If you want to know how a particular cancer type is diagnosed, please pick the type you are interested in on our cancer types page

Cancer types page

Support after a cancer diagnosis

Being told you have cancer is a huge shock. You may feel overwhelmed by emotions like anger, sadness, confusion, anxiety or even guilt. We are here for you. We have information on coping with cancer and a range of free services to help. 

Coping with cancer 

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Tests after diagnosis

If you have been diagnosed with cancer, you may need more tests to give your doctor more information about your cancer. For example, the size of the cancer and if it has spread to other tissues. This is called staging. Staging helps your doctor to decide on the best treatment for you. Scans like MRI and PET can help to stage a cancer.

Read about your cancer type to see what staging tests might be recommended for you.


Talk to a Cancer Nurse

Support Line

Support Line

Our Cancer Nurses offer confidential advice, support and information for anyone affected by cancer. Call or email supportline@irishcancer.ie. Video calls available. Mon-Fri: 9am-5pm
Support Line
Our Daffodil Centres

Our Daffodil Centres

Our Daffodil Centres in 13 hospitals nationwide are staffed by Cancer Nurses and trained volunteers who provide face-to-face advice, support and information for anyone affected by cancer.
Our Daffodil Centres