Unusual Cancers of Childhood (PDQ®): Treatment - Patient Information [NCI] - Other Rare Unusual Cancers of Childhood
When the type of cancer cells or tissue removed is different from the type of cancer cells expected to be found, a diagnosis of cancer of unknown primary may be made. The cells in the body have a certain look that depends on the type of tissue they come from. For example, a sample of cancer tissue taken from the breast is expected to be made up of breast cells. However, if the sample of tissue is a different type of cell (not made up of breast cells), it is likely that the cells have spread to the breast from another part of the body.
Adenocarcinomas, melanomas, and embryonal tumors are common tumor types that appear and it is not known where the cancer first formed. Embryonal tumors such as rhabdomyosarcomas and neuroblastomas are most common in children.
Treatment depends on what the cancer cells look like under a microscope, the patient's age and symptoms, and where the cancer has spread in the body. Treatment is usually chemotherapy or radiation therapy.