Toxicity: The extent to which something is poisonous or harmful.

Transdermal: Absorbed through the unbroken skin. (some pain relievers are delivered in this fashion).

Transitional Cell: A cell that varies in shape depending on whether the tissue is being stretched. Transitional cells may be stretched without breaking apart, they line hollow organs such as the bladder.

Transitional Cell Carcinoma: A type of cancer that develops in the lining of the bladder, ureter or renal pelvis (the part of the kidney that collects, holds and drains urine).

Tumor Load: Refers to the number of cancer cells, the size of a tumor or the amount of cancer in the body. Also called Tumor Burden.

Tumor Specific Antigen: A protein or other molecule that is unique to cancer cells or is much more abundant in them. These molecules are usually found in the plasma (outer) membrane, and they are thought to be potential targets for Immunotherapy or other types of anticancer treatment.

Tyrosine Kinase Receptor: A drug that interferes with cell communication and growth and may prevent tumor growth. Some Tyrosine Kinase Inhibitors are used to treat cancer.