NCI Dictionary of Cancer Terms

The NCI Dictionary of Cancer Terms features 8,354 terms related to cancer and medicine.

We offer a widget that you can add to your website to let users look up cancer-related terms. Get NCI’s Dictionary of Cancer Terms Widget.

tumor-infiltrating lymphocyte
(TOO-mer-IN-fil-TRAY-ting LIM-foh-site)
A type of immune cell that has moved from the blood into a tumor cell. Tumor-infiltrating lymphocytes are thought to be a sign that the immune system is trying to attack the cancer. In cancer therapy, tumor-infiltrating lymphocytes are removed from a patient’s tumor, then treated in the laboratory with substances that make them grow and turn into cells that can kill the patient’s cancer cells. Large numbers of these activated lymphocytes are then reinfused into the patient to help the immune system fight cancer. Also called TIL.