The following stages are used for thymoma:
In stage I, cancer is found only within the thymus. All cancer cells are inside the capsule (sac) that surrounds the thymus.
In stage II, cancer has spread through the capsule and into the fat around the thymus or into the lining of the chest cavity.
In stage III, cancer has spread to nearby organs in the chest, including the lung, the sac around the heart, or large blood vessels that carry blood to the heart.
Stage IV is divided into stage IVA and stage IVB, depending on where the cancer has spread.
In stage IVA, cancer has spread widely around the lungs and heart.
In stage IVB, cancer has spread to the blood or lymph system.
Thymic carcinomas have usually spread to other parts of the body when diagnosed.
The staging system used for thymomas is sometimes used for thymic carcinomas.