The term "germ cell" refers to giving of life, as in "germinate" (not from "germs" as in bacteria). Germ cells get their name because they normally produce the specialized cells that create life: sperm and egg cells - the sex cells needed for reproduction.
Germ cell tumors are growths that occur in children, teens and adults. Germ cell tumors are rare, about 900 children and adolescents are diagnosed in the United States each year. They make up only 4% of all cancers in children and adolescents.Germ cell tumors most commonly appear in the gonads (sex organs). However, these tumors can arise in several different places within the body:
- The testes (boys)
- The ovaries (girls)
- The abdomen and pelvis
- The mediastinum (part of the chest between the breastplate and the spinal column)
- The brain
Germ cells develop early in life. At about four weeks, the earliest germ cells in the growing fetus migrate from their point of origin to the gonadal area (the area of the sex organs). If germ cells do not reach their intended destination, tumors occur wherever these cells end up. Germ cell tumors can be malignant (life-threatening) or benign (not life-threatening).
Malignant germ cell tumors include several types of cancer, such as immature teratoma, yolk sac tumor and choriocarcinoma. They can destroy the testes or ovaries and can spread to other parts of the body.Benign germ cell tumors include certain kinds of teratomas. A teratoma is a tumor that may contain several different types of tissue, such as hair, muscle and bone. Although not as difficult to treat as malignant tumors, benign germ cell tumors can cause problems because of their size. They can be quite large, even in a newborn.
Symptoms of Germ Cell TumorsThe signs and symptoms of germ cell tumors differ depending on where the tumors begin:
- Testicular germ cell tumors: Commonly seen as a painless mass in the scrotum (the skin that holds the testicles), parents are most likely to notice the development of these tumors in small boys. In teen-aged boys, testicular tumors may be more difficult to detect if parents and teens are uncomfortable discussing such intimate matters.
- Ovarian and abdominal tumors: There may be abdominal pain or constipation. As a tumor gets bigger, it may become evident as an abdominal mass.
- Mediastinal tumors: These tumors form in the part of the chest between the breastbone and spinal column and can grow without symptoms until they become quite large. Once large, they can cause chest pain, shortness of breath and wheezing.
- Sacrococcygeal teratomas: These tumors are found as a mass that protrudes around the anus and are usually diagnosed in newborns and removed. However, these tumors can also be internal, in which case they may grow unnoticed for many months and may become malignant. Internal tumors may cause constipation, urinary retention and pain.
Diagnosing Germ Cell TumorsIn addition to a complete medical history and physical examination, diagnostic tests for germ cell tumors may include the following:
- Blood tests: These may require taking samples for blood chemistry, blood cell count, genetics and certain proteins called tumor markers such as AFP and bhCG that are produced by some germ cell tumors.
- Biopsy: A sample of tissue is removed and examined under a microscope to evaluate cell types, the extent of disease and other factors.
- Imaging studies: There are several ways to get a clear picture of the tumor and surrounding structures, including:
- CT scan (CAT Scan)
- Magnetic Resonance Imaging (MRI)
StagingAfter a germ cell tumor is diagnosed, doctors need to assess how advanced it is, which is called staging the tumor. To stage the tumor, doctors will need to know the size of the tumor, if it has spread (metastasized) and if it has affected lymph nodes and other tissues.
Because germ cell tumors can vary greatly, and can arise in different parts of the body, they can be difficult to stage. However, the Children’s Oncology Group (COG) developed the following system for staging germ cell tumors.
COG Germ Cell Tumor Staging System
- Stage I: The tumor has been entirely removed, and tumor markers are normal.
- Stage II: Microscopic traces of the tumor are still present after surgery; tumor markers do not return to normal following surgery.
- Stage III: Visible traces of tumor are left behind after initial treatment, and the lymph nodes are affected.
- Stage IV: The tumor has spread from its original site to other, more distant areas of the body.