Thymus Cancer: Stages

What does stage of cancer mean?

The stage of a cancer is how much and how far it has spread in your body. Your healthcare provider uses exams and tests to find out the size of the tumor and where it is. He or she can also see if the cancer has grown into nearby areas, and if it has spread to other parts of your body. The stage is one of the most important things to know when deciding on treatment.

What are the stages of thymus cancer?

The system used most often to stage thymus tumors is known as the Masaoka system. This system uses Roman numerals from I to IV (1 to 4) for the different stages:

Stage I:

  • The tumor is contained within the thymus.

Stage IIA:

  • The tumor has grown into the capsule surrounding the thymus.

Stage IIB:

  • The tumor has grown into nearby fatty tissue. It may be sticking to the covering of the lungs (mediastinal pleura) or the lining around the heart (pericardium). 

Stage III:

  • The thymoma has grown into nearby tissues or organs in your lower neck or upper chest. These may include your pericardium, lungs, or major blood vessels going in or out of the heart.

Stage IVA:

  • The thymoma has spread widely through the lining of your lungs (pleura) and/or pericardium.

Stage IVB:

  • The thymoma has spread through blood or lymph vessels to other organs. These can include your liver or bones.

Talking with your healthcare provider

Once your cancer is staged, your healthcare provider will talk with you about what the stage means for your treatment. Make sure to ask any questions or talk about your concerns.