Staging and prognosis of mesothelioma

Staging

After mesothelioma has been diagnosed, you will have further tests to work out the extent of the disease in the chest or abdomen and whether the disease has spread to other parts of the body and, if so, by how much and how far. This process is called staging. The main test to stage mesothelioma is a CT scan. You may have had a CT scan earlier when mesothelioma was suspected, or during a CT-guided core biopsy. If that CT scan showed advanced disease, a further CT scan may not be necessary.

Staging systems for mesothelioma

Staging is a way to describe the cancer and whether and how far it has spread beyond its original site. Doctors use particular systems when staging different types of mesothelioma.

TNM staging system for pleural mesothelioma

The staging system recommended for pleural mesothelioma is the international tumour–node–metastasis or TNM staging system.

PCI system for peritoneal mesothelioma

Peritoneal mesothelioma is usually staged using the peritoneal cancer index (PCI). The area of the abdomen and pelvis is divided into 13 regions. A score out of 3 is given to any tumours found in these regions. The PCI is calculated by adding together the scores for all 13 regions, with a maximum score of 39. The higher the PCI, the further the cancer has spread.

Tests before surgery

If radical surgery is being considered as a suitable treatment option, you may have other scans and procedures to check whether  mesothelioma has spread to other areas of the body.

These may include the following:

FDG-PET – A positron emission tomography (PET) scan detects radiation from a low-level radioactive drug that is injected into the body. In an FDG-PET, the drug used is called fluorodeoxyglucose (FDG). The FDG shows up areas of abnormal tissue.

MRI scan – A magnetic resonance imaging (MRI) scan uses a powerful magnet and radio waves to create detailed, cross-sectional pictures of the soft tissues in your body. The noisy, narrow machine makes some people feel anxious or claustrophobic. If you think you may become distressed, mention it beforehand to your medical team. You may be given a mild sedative to help you relax.

Endobronchial ultrasound (EBUS) – A tube called a bronchoscope, which has a small ultrasound probe on the end, will be put down your throat into your trachea. This allows the respiratory physician to identify lymph nodes for biopsy.

Surgical staging – Before radical surgery for pleural mesothelioma, if it’s unclear from the PET scan whether mesothelioma has spread, the surgeon may remove a sample of lymph nodes and tissue from other areas of the body. Surgical staging is not recommended before a peritonectomy for peritoneal mesothelioma.

Prognosis

Prognosis means the expected outcome of a disease. You may wish to discuss your prognosis with your doctor, but it is not possible for anyone to predict the exact course of the illness.

Mesothelioma behaves differently in different people. It is often present for many months before being diagnosed at an advanced stage, which will affect  prognosis. After diagnosis, mesothelioma may progress quickly or more slowly. If it progresses slowly, some people may live for several years or longer.

Your doctor will consider several factors when discussing prognosis with you, including:

• the type of mesothelioma cell
• the stage
• the type of treatment you are able to have
• your symptoms, such as weight loss or pain
• your blood count – people with normal levels of blood cells usually have a better prognosis
• your overall health – recovering quickly after procedures tends to suggest a better outcome.

While knowing the stage helps doctors plan treatment, it is not always useful for working out prognosis for people with mesothelioma. This is partly because it is hard to predict how quickly mesothelioma will grow. In general, the earlier cancer is diagnosed, the better the outcome. If the cancer has advanced to a point where it is difficult to treat successfully, the priority will be to relieve symptoms and improve your quality of life.