NCI Dictionary of Cancer Terms

The NCI Dictionary of Cancer Terms features 8,470 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 to try and attack the cancer. In cancer therapy, tumor-infiltrating lymphocytes are removed from a patient’s tumor and are then treated in the laboratory with substances that activate the lymphocytes to help them better kill the patient’s cancer cells. Large numbers of these activated lymphocytes are then given back to the patient to help the immune system fight cancer. Also called TIL therapy.