Key Points for This Section

Tests done to detect thymoma or thymic carcinoma are also used to stage the disease. There are three ways that cancer spreads in the body. The following stages are used for thymoma: Noninvasive thymoma (stage I) Invasive thymoma (stage II, stage III, and stage IV) Thymic carcinomas have usually spread to other parts of the body when diagnosed.

Tests done to detect thymoma or thymic carcinoma are also used to stage the disease.

Staging is the process used to find out if cancer has spread from the thymus to other parts of the body. The findings made during surgery and the results of tests and procedures are used to determine the stage of the disease. It is important to know the stage in order to plan treatment.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.
• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

The following stages are used for thymoma:

Noninvasive thymoma (stage I)

In stage I, cancer is found only within the thymus. All cancer cells are inside the capsule (sac) that surrounds the thymus.

Invasive thymoma (stage II, stage III, and stage IV)

Invasive thymoma includes stage II, stage III, and stage IV.

• 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.

Glossary Terms

A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.

A tube through which the blood circulates in the body. Blood vessels include a network of arteries, arterioles, capillaries, venules, and veins.

Primary bone cancer is cancer that forms in cells of the bone. Some types of primary bone cancer are osteosarcoma, Ewing sarcoma, malignant fibrous histiocytoma, and chondrosarcoma. Secondary bone cancer is cancer that spreads to the bone from another part of the body (such as the prostate, breast, or lung).

Cancer that forms in tissues of the breast, usually the ducts (tubes that carry milk to the nipple) and lobules (glands that make milk). It occurs in both men and women, although male breast cancer is rare.

A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.

The smallest type of blood vessel. A capillary connects an arteriole (small artery) to a venule (small vein) to form a network of blood vessels in almost all parts of the body. The wall of a capillary is thin and leaky, and capillaries are involved in the exchange of fluids and gases between tissues and the blood.

In medicine, a sac of tissue and blood vessels that surrounds an organ, joint, or tumor. A capsule is also a form for medicine that is taken by mouth. It usually has a shell made of gelatin with the medicine inside.

Cancer that begins in the skin or in tissues that line or cover internal organs.

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

Cancer that has spread beyond the layer of tissue in which it developed and is growing into surrounding, healthy tissues. Also called infiltrating cancer.

One of a pair of organs in the chest that supplies the body with oxygen, and removes carbon dioxide from the body.

The clear fluid that travels through the lymphatic system and carries cells that help fight infections and other diseases. Also called lymphatic fluid.

A thin tube that carries lymph (lymphatic fluid) and white blood cells through the lymphatic system. Also called lymphatic vessel.

The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases. This system includes the bone marrow, spleen, thymus, lymph nodes, and lymphatic vessels (a network of thin tubes that carry lymph and white blood cells). Lymphatic vessels branch, like blood vessels, into all the tissues of the body.

The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a “metastatic tumor” or a “metastasis.” The metastatic tumor contains cells that are like those in the original (primary) tumor. The plural form of metastasis is metastases (meh-TAS-tuh-SEEZ).

A part of the body that performs a specific function. For example, the heart is an organ.

The original tumor.

The extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has spread from the original site to other parts of the body.

Performing exams and tests to learn the extent of the cancer within the body, especially whether the disease has spread from the original site to other parts of the body. It is important to know the stage of the disease in order to plan the best treatment.

A procedure to remove or repair a part of the body or to find out whether disease is present. An operation.

A tumor of the thymus, an organ that is part of the lymphatic system and is located in the chest, behind the breastbone.

An organ that is part of the lymphatic system, in which T lymphocytes grow and multiply. The thymus is in the chest behind the breastbone.

A group or layer of cells that work together to perform a specific function.

An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancerous), or malignant (cancerous). Also called neoplasm.

A blood vessel that carries blood to the heart from tissues and organs in the body.