Tissue array

—small cylinders of tissue punched from 1,000 individual tumor biopsy specimens embedded in paraffin. These cylinders are then arrayed in a large paraffin block, from which 200 consecutive tissue sections can be cut, allowing rapid analysis of multiple arrayed samples by immunohistochemistry or in situ hybridization.

Tomography

—any of several techniques for making x-ray pictures of a predetermined plane section of a solid object by blurring out the images of other planes.

Tomosynthesis

—a variation of tomography in which several radiographs of a patient are taken at different angles, and back-projection of the resulting images produces a light distribution in a chosen three-dimensional volume of space that replicates the same volume in the patient.

Transcription

—synthesis of RNA by an enzyme called RNA polymerase that uses a DNA template; the first step in protein biosynthesis.

Transcriptome

—the complete collection of transcribed elements of the genome. In addition to mRNAs, it also represents noncoding RNAs which are used for structural and regulatory purposes. Alterations in the structure or levels of expression of any one of these RNAs or their proteins can contribute to disease.

Translational research

—the research needed to move the fruits of basic research into clinical practice.

Tumor

—an abnormal mass of tissue that results from excessive cell division that is uncontrolled and progressive, also called a neoplasm. Tumors perform no useful body function. They may be either benign (not cancerous) or malignant.

Tumor marker

—any substance or characteristic that indicates the presence of a malignancy.

Tumor suppressor genes

—genes that slow cell division or that cause cells to die at the appropriate time. Mutations in these genes can lead to uncontrolled cell growth and the development of cancer.

Tumorigenesis

—the induction of the malignant growth of abnormal cells.

Ultrasound

—use of inaudible, high-frequency sound waves to create an image of the body.

Venipuncture

—the puncture of a vein (usually in the arm) with a hollow bore needle for the purpose of obtaining a blood specimen.

X-ray

—a type of ionizing radiation used for imaging purposes that uses energy beams of very short wavelengths (0.1 to 1000 angstroms) that can penetrate most substances except heavy metals.