TBI: Total body irradiation. This type of radiation therapy is often given to patients undergoing a stem cell transplant and is effective in killing cancer and normal bone marrow / immune tissue.

T Cell Depletion: The removal, usually in part, of T cell lymphocytes, a type of white blood cell, from bone marrow donated by another person to prevent or reduce the risk of severe graft versus host disease.

Thoracentesis (Pleural Tap): A procedure to remove an abnormal collection of fluid from the area between the two layers (pleura) covering the lung. This is done to determine what is causing the fluid to form and/or to provide relief from shortness of breath.

Thoracoscopic: A procedure that uses a lighted scope to visualize the pleural space in the lung and allows for less invasive thoracic surgical procedures.

Thrombocytes: Platelets or cells needed for the blood to clot. (See platelets)

Thrombocytopenia: An abnormally low number of platelets. If your platelet count gets too low, bleeding may occur.

Thrombocytosis: An abnormally high number of platelets that can be associated with either excessive bleeding or blood clotting

Tissue Typing: Another term for HLA-typing. (See Human Leukocyte Antigens)

Transformation: The change that a normal cell undergoes as it becomes malignant.

Transfusion: The transfer of blood or blood products from one person to another.

Tumor: An abnormal growth or mass of body cells that serves no purpose. It may be either benign or malignant.

Tumor Debulking: Surgically removing as much of the tumor as possible.

Tumor Lysis Syndrome: A syndrome where cancer treatment causes massive cancer cell death that results in the build up of uric acid crystals and other chemicals in the blood stream (such as sodium and potassium).

Tumor Marker: A substance in blood or other body fluids that may suggest that a person has a certain type of cancer.

Tumor Necrosis Factor: A type of biological therapy that causes cancer cells to die.