A solid tumour is an abnormal mass of tissue that usually does not contain cysts or liquid areas. Solid tumours may be benign (not cancer), or malignant (cancer). Solid tumour types are named according to the type of cell they originate from. Examples of solid tumours are sarcomas, carcinomas, and lymphomas. Leukaemias (cancers of the blood) generally do not form solid tumours.
A tumour-infiltrating lymphocyte (TIL) is a type of immune cell that has moved from the blood into a tumour. TILs can recognise and kill cancer cells. In cancer therapy, tumour-infiltrating lymphocytes are removed from a patient’s tumour, grown in large numbers in a laboratory, and then given back to the patient to help the immune system kill the cancer cells.