Diagnosis & staging
Thymus cancers are very rare.
The thymus sits just in front of and above your heart and may extend up to the bottom of your neck. The thymus has two lobes (sections) that are surrounded by a thin layer of tissue. It is made up of two types of cells: epithelial cells and lymphocytes.
Image of thymus
thymus is part of the lymphatic system. T Lymphocytes are a type of white blood
cell that develop in the thymus, especially in early life. These cells help
protect the body from infections and viruses. If lymphocytes become cancerous,
they can develop into lymphoma. For more information: Lymphoma
Epithelial cells line the thymus. Thymus-related cancers, such as thymoma and thymic carcinoma, start in these cells.
Thymus cancers have different names including thymomas, thymic carcinomas, and thymic epithelial tumour.
Thymic carcinoid tumours are very rare types of cancers called neuroendocrine tumours (NETs).
There are often no symptoms of thymus cancer. Because of this, many people diagnosed with thymus cancer will be at an advanced stage.
- Shortness of breath
- Difficulty breathing (dyspnea)
- Difficulty swallowing (dysphagia)
- Chest tightness or pain
- Swelling in your neck and face
- Feeling light-headed
Advanced thymus cancer may cause chest pain.
Some people with this cancer may also have an immune disorder or low red blood cell counts.
If you have any signs or symptoms that you are worried about, please talk to your family doctor or nurse practitioner.
Thymus tumours are often found when a chest x-ray is done for another reason.
Tests that may help diagnose thymus cancer include:
- Chest x-ray or CT (Computed tomography) scan: to see the tumour and if the cancer has spread.
- Magnetic Resonance Imaging (MRI): will show if the cancer has spread.
- Fine needle biopsy: a doctor uses a needle to remove a small piece of tissue. A specialist doctor (pathologist) will examine the tissue under a microscope.
- Usually grow slowly.
- Non-invasive thymomas have not grown through the outer layer of the thymus (capsule). Often removed with surgery.
- Invasive thymomas have grown into other organs or areas around the thymus. Can be hard to remove.
- Less common.
- Grows quickly.
- Has often spread at time of diagnosis.
Staging describes the cancer. Staging is based on how much cancer is in the body, where it was first diagnosed, if the cancer has spread and where it has spread to.
The stage of the cancer can help your health care team plan your treatment. It can also tell them how your cancer might respond to treatment and the chance that your cancer may come back (recur).
The modified Masaoka system is most commonly used for this type of cancer.
- Stage 1: Tumour is only in the thymus.
- Stage 2: Tumour has grown through the thymus capsule. Tumour may have grown into fat around the thymus or tumour is attached to the pleura (layer of tissue covering lungs and lining chest cavity).
- Stage 3: Tumour has grown into nearby organs or tissues, such as the lungs.
- Stage 4A: Cancer has spread widely through the pleura or pericardium (the sac that surrounds your heart).
- Stage 4B: Cancer has spread to other parts of the body.
- Stage 1: Tumour is in the thymus or has grown into surrounding fat. Tumour may also have grown into the pleura next to the thymus.
- Stage 2: Tumour has grown into the pericardium.
- Stage 3A: Tumour has grown into any of these areas:
- Nearby large veins in the upper chest.
- Large blood vessels going into or leaving the lung outside of the pericardium.
- Nerve to the diaphragm (called the phrenic nerve).
- Chest wall.
- Stage 3B: Tumour has grown into any of these areas:
- Large artery leaving the heart (called the aorta).
- An artery branching off the arch (top part) of the aorta.
- Large blood vessels going into or leaving the lung within the pericardium.
- Muscle layer of the heart (called the myocardium).
- Trachea (windpipe).
- Esophagus (swallowing tube that brings food to your stomach).
- Stage 4A: Cancer has spread to lymph nodes around the thymus (perithymic lymph nodes) or cancer has spread to a part of the pleura or pericardium that is not attached to the main tumour.
- Stage 4B:
- Cancer has spread to lymph nodes deeper into the thorax (part of your body between your neck and abdomen) called the intrathoracic lymph nodes. Or cancer has spread to lymph nodes in the neck (cervical lymph nodes).
- Cancer has spread to other parts of your body (distant metastasis) such as the liver.