What are germ cell tumors?
Germ cell tumors are malignant (cancerous) or nonmalignant (benign, noncancerous) tumors that are comprised mostly of germ cells. Germ cells are the cells that develop in the embryo (fetus, or unborn baby) and become the cells that make up the reproductive system in males and females. These germ cells follow a midline path through the body after development and descend into the pelvis as ovarian cells or into the scrotal sac as testicular cells. Most ovarian tumors and testicular tumors are of germ cell origin. The ovaries and testes are called gonads.
Tumor sites outside the gonad are called extragonadal sites. The tumors also occur along the midline path and can be found in the head, chest, abdomen, pelvis and sacrococcygeal (lower back) area.
Germ cell tumors are rare. Germ cell tumors account for about 2 - 4% of all cancers in children and adolescents younger than age 20.
Germ cell tumors can spread (metastasize) to other parts of the body. The most common sites for metastasis are the lungs, liver, lymph nodes and central nervous system. Rarely, germ cell tumors can spread to the bone, bone marrow and other organs.