A germ cell tumor that begins in the reproductive cells of testes or ovaries is called a gonadal tumor. Rarely, germ cell tumors occur in other parts of the body. These tumors that are outside of the gonads are called extragonadal tumors. Germ cell cancers, even when diagnosed at an advanced stage, tend to have a favorable outlook (prognosis). The prognosis is even better when the cancer is detected early.
Gonadal germ cell tumors
Most tumors of the testicles start in the germ cells. Experts classify testicular cancer into two main categories:
- Seminoma. Seminomas develop from germ cells that produce sperm. This type of cancer can be successfully treated by surgery, radiation therapy or chemotherapy.
- Nonseminoma. Nonseminomas are usually made up of various types of cells. Nonseminomas generally respond well to combined treatment, which may include surgery, radiation and chemotherapy.
Ovarian germ cell tumors — cancer that starts in egg cells — are rare. Most ovarian cancers are epithelial cell that start in the tissues of the ovary.
Extragonadal germ cell tumors
Germ cell tumors that are outside of the gonads are rare. They may grow in any location where stray germ cells settle in the body.
- Brain germ cell tumors. Brain germ cell tumors usually form in the center of the brain. Read more about diagnosis and treatment of tumors that develop in the brain at pediatric brain tumors and brain tumors.
- Chest germ cell tumors. The most common site of extragonadal germ cell tumors is in the chest (mediastinum). Mediastinal germ cell tumors typically occur in young men.
- Abdominal germ cell tumors. Abdominal (retroperitoneal) germ cell tumors are rare and likely to result from testicular cancer spreading to lymph nodes.