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Types of Cancer > Pediatric Cancers > Brain Tumors (Childhood) > Overview
Medulloblastoma: Overview
Neha Vapiwala, MD and John P. Plastaras, MD, PhD
Affiliation:
Abramson Cancer Center of the University of Pennsylvania
Last Modified: August 22, 2007
Some Background
Almost 20% of all childhood cancers start in the central nervous system (CNS), which consists of the brain, the spinal cord, and the surrounding fluid (cerebrospinal fluid, or CSF), lining tissues (meninges) and bone (cranium and vertebrae).
In the past several years, the incidence of pediatric CNS tumors has been increasing. This increase is partially explained by medical advances that have led to earlier detection and diagnosis of brain tumors.
There are many different types of pediatric CNS cancers, all of which have long and rather complicated names. The diagnosis typically depends on two things: 1) where in the CNS the tumor starts, or the location , and 2) how the tumor looks under a microscope, also known as the histology . Primary brain tumors are tumors that arise in the brain, while primary spinal tumors grow in the spinal cord. However, some brain tumors can spread to involve parts of the spine, and vice versa. On occasion, certain types of tumors can even spread to areas outside of the CNS, such as distant bones or bone marrow.
This is where the concept of "staging" the tumor comes in, and each tumor type has its own specific staging system. The purpose of assigning a cancer stage is to help predict outcome, as well as to guide treatment by appropriately applying the data acquired from clinical pediatric cancer trials. Of course, ultimately, every cancer treatment plan is individualized for every patient, and takes into account not only the stage and the clinical data, but also the goals and desires of the patient and his or her family.
What is medulloblastoma?
Medulloblastoma is a type of brain tumor that occurs in infants and young children. It represents about 20% of all pediatric CNS cancers. By definition, medulloblastomas occur in the cerebellum, which is the back part of the brain that controls walking, balance and fine motor coordination, among other things.
Medulloblastoma is a long name made up of three smaller words: medulla = Latin for marrow, meaning inner substance or core; blastos = Greek word for germ, meaning young, primitive, not fully developed; and oma = Greek for tumor. In other words, this is a tumor of primitive, undeveloped cells located inside the cerebellum.
Who gets this tumor, and how?
Medulloblastoma almost always occurs in children less than 15 years old, and most commonly between the ages of 5-6 years. About 20% of the cases occur in infants less than two years old. This disease appears to be more common in boys than girls.
No clear or definitive causes of medulloblastoma have been identified. It does not appear to "run in families" or to be directly inherited from the parents. However, medulloblastoma is associated with certain chromosomal abnormalities that probably occur at some point during a child's development. This includes not only development after birth, but also the prenatal period before a baby is born, while it is still a growing embryo or fetus. One possible cause that has been suggested is exposure of the fetus to certain causative viruses or environmental agents, but this theory remains under investigation.