Brain tumors - primary
Description
An in-depth report on the causes, diagnosis, and treatment of brain tumors.
Alternative Names
Gliomas; Medulloblastoma
Causes
Several defective genes are involved in the cancer process. Genes that cause cancer proliferation (called oncogenes) and those that normally suppress tumors but are defective (tumor suppressor genes) may play separate roles in a step-by-step process leading to primary brain cancer. Several avenues of investigation are in progress to determine both basic causes and the triggers for such genetic defects.
Specific Genetic Abnormalities.
Numerous specific brain tumors, including glioblastomas, anaplastic astrocytomas, and medulloblastomas, are the result of abnormal or missing genes:
-
Researchers have discovered a defective gene MMAC1 (Mutated Multiple Advanced Cancers) in the majority of the glioblastomas (although not low-grade gliomas). The MMAC1 gene determines how aggressive a tumor will be.
-
Another defective gene, known as the Patched 2 gene, which appears to promote tumor growth, has been found in about half of all medulloblastomas.
Inherited Genetic Factors.
A large population study reported that family clusters of brain cancer occurred in a small fraction of astrocytomas, indicating that inherited factors may play a direct role in some cases.
Acquired Genetic Defects.
Genetic abnormalities that cause brain tumors are not usually inherited but mostly occur as a result of environmental insults or other factors that affect genetic materials (DNA) in the cells. Researchers are studying several environmental assaults that might trigger brain tumors in susceptible individuals. Among them are:
-
Abnormal development in the womb
-
Viruses
-
Hormones
-
Chemicals
-
Ionizing radiation
-
Review Date: 10/19/2006
-
Reviewed By: Harvey Simon, M.D., Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.
|
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's
accreditation program
is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s
editorial process
. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).
|
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-2007
A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
