Diagnosing Germ Cell Tumors
In addition to a complete medical history and physical examination, diagnostic tests for germ cell tumors often 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 alpha-fetoprotein (AFP) and the beta subunit of the human chorionic gonadotropin (b-HCG) 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:
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After a germ cell tumor is diagnosed, doctors need to assess how advanced the tumor is. This process is called staging the tumor. To stage a tumor, doctors 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, doctors use the following system for staging germ cell tumors:
- 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.
Prognosis of Germ Cell Tumors
The prognosis of germ cell tumors depends on a number of factors, including the location of the tumor and the different cellular characteristics. Germ cell tumors of the gonads have a better prognosis than extragonadal germ cell tumors. Benign teratomas have an excellent prognosis with surgery. Malignant tumors require surgery and chemotherapy.
Many tumors produce proteins in the blood that doctors can measure to show the rate of tumor growth and the success of treatment. Two proteins that can be used as markers are AFP and b-HCG. The rate at which these markers fall after surgery or chemotherapy is now recognized as a prognostic factor.
In general, later stage tumors or tumors that have spread from their point of origin to other parts of the body require more therapy and are at risk for poorer outcomes. Patients older than 15 (or in general those diagnosed after puberty) are at risk for poorer outcomes than younger patients.
Causes of Germ Cell Tumors
The exact cause of germ cell tumors is not completely understood. However, these tumors seem to arise when cells which normally migrate to the gonads (sex organs) in the developing embryo fail to reach the right location. Some tumors arise in children with extra genetic material or more than the normal number of chromosomes in all body cells. Only a few risk factors for germ cell tumors are known for sure. Caucasian males under age 20 are about 7 times more likely to develop a germ cell in the testis compared to African American males. Caucasian and African American females have similar risk of ovarian and other germ cell tumors. Boys born with undescended testes have a higher risk of developing a germ cell tumor of the testis. Even if only one testis is undescended, the higher risk applies to both testes. The medical term for undescended testes is cryptorchidism.