Overview

Germ cells are special cells in a developing embryo (fetus) that become the testicles in boys and the ovaries in girls. Rarely, during development of the embryo, these cells travel to other areas of the body and become cancerous. Cancer occurs when cells in the body become abnormal and multiply without control or order. The cells then form a mass of tissue, called a tumor. A germ cell tumor can be benign (noncancerous) or malignant (cancerous). Some places that germ cells may travel to include the chest, abdomen, or brain.

This summary covers germ cell tumors that are extracranial (occurring in places other than the brain) and extragonadal (occurring outside of the reproductive organs). Extracranial, extragonadal germ cell tumors that occur in early childhood generally begin in the sacrum and the coccyx, which are the lowest parts of the spinal column. Extracranial, extragonadal germ cell tumors in people in their teen years and young adulthood are often located in the chest.

For information on a germ cell tumor in the brain, read Cancer.Net Guide to Central Nervous System Tumors, Childhood.

For more information on a germ cell tumor in the reproductive organs, read Cancer.Net's Guide to Ovarian Cancer and Guide to Testicular Cancer.

Statistics

Extracranial, extragonadal germ cell tumors are rare. Each year, about 900 children and adolescents under the age of 20 are diagnosed with germ cell tumors.

Extracranial germ cell tumors, including those that occur in the reproductive organs, account for about 7% of all cancers in children younger than 20 and about 16% in children age 15 to 19. More than 60% of childhood germ cell tumors are extragonadal and most commonly occur in the sacrum and coccyx, chest, and abdomen. The overall relative survival rate (the percentage of people who survive at least five years after the cancer is detected, excluding those who die from other diseases) ranges from 77% to 87%.

Cancer statistics should be interpreted with caution. It is not possible to tell a person how long he or she will live with a germ cell tumor. Because survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this tumor.

Source: National Cancer Institute Surveillance Epidemiology and End Results (SEER) database. 

Find out more about basic cancer terms used in this section.