Brain Tumors: Primary - Risk Factors

Risk Factors

Nearly 360,000 people in the U.S. are living with brain cancer. Men are at higher risk than women for most brain tumors. Primary malignant brain tumors are still uncommon and represent only 1.3% of all cancers diagnosed in the United States and 2.4% of all deaths due to cancer.

Primary brain cancers are rare, occurring in slightly more than 11 people per 100,000 per year. There has been some evidence of a growing incidence of brain cancer among the elderly since the 1980s. The increase, however, is most likely due to the rise in incidence of non-Hodgkin's lymphomas -- which can occur in the brain. When this malignancy is eliminated, any increase in other tumors is not significant.

Age

The average age of diagnosis for brain tumors is 57, and about 90% of primary brain tumors occur in adults. These tumors can develop at all ages, usually peaking in two age groups.

• In adults, ages 55 - 65
• In children, ages 3 - 12

Risk Factors in Children. Tumors in the central nervous system are now the most common primary cancers in children, but they are still rare. An estimated 3,110 benign or malignant brain tumors are expected to be diagnosed in children each year. Brain tumors in children are more likely to occur in the cerebellum, the midbrain, or the optic nerve.

The incidence has increased over the past years, but there is some evidence that this increase is only due to better diagnostic procedures. The mortality rate has actually decreased. Researchers have attempted to uncover risk factors for childhood brain cancer. There may be some association between a higher risk and the following conditions:

• Children treated with radiation to the head for leukemia and who have a specific genetic defect may face a high risk for brain cancer. (It should be noted that for children without this defect, the risk is very small.)
• Having parents with specific cancers. (According to a 2000 study, having parents with nervous system cancers, colon cancer, or cancer in the salivary glands increased the risk of specific brain tumors in their children.)