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National Cancer Institute
NCI To Study Brain Tumors and Their Causes

CancerNet from the National Cancer Institute
CANCER FACTS
National Cancer Institute
National Institutes of Health

NCI To Study Brain Tumors and Their Causes

The National Cancer Institute (NCI) is conducting a comprehensive study of malignant and benign adult brain tumors to identify environmental and genetic causes for these serious, but poorly understood diseases.

Researchers will examine numerous factors that may affect brain cancer incidence, one of which is cellular telephone use. Public concern has surfaced over the possibility that hand-held cellular telephones, as well as other sources of electromagnetic fields (EMFs), cause brain cancer.

An estimated 17,500 Americans will be diagnosed with cancer of the brain or central nervous system in 1994, and 12,600 people are expected to die of the disease this year.

The recorded incidence of brain cancer in the United States has increased by about 1 percent per year since 1973, and the death rate by somewhat less than 1 percent per year. The increase is seen mainly in people who are 65 years of age or older; their rates have increased 3 percent per year since 1980.

A substantial part of the increase in brain cancer rates, especially in the older groups, scientists believe is due to the advent of sophisticated scanning and imaging equipment, which are better able to detect brain tumors. However, it is not clear whether the increased incidence is completely explainable by improved diagnosis, or whether the trend might also reflect increased exposure to carcinogens yet to be identified.

The major causes of brain tumors are unknown, said Peter Inskip, at NCI's Division of Cancer Etiology. Factors shown to have a link to brain tumors, such as certain heritable conditions and childhood radiotherapy to the head, are uncommon and account for only a small percentage of the total number of cases.

The NCI case-control study will be conducted at hospitals in Phoenix, Pittsburgh, and Boston, and will include 800 newly diagnosed brain tumor cases and an equal number of matched controls. The controls will be patients admitted to the same hospitals, with any of a variety of other diseases or conditions, not including cancer.

Researchers plan to gather information about possible risk factors through a combination of in-person interviews, self-administered questionnaires, and biochemical and molecular genetic analyses of blood and tumor samples. The study will improve on previous studies of occupational risk factors for brain cancer by incorporating detailed job-specific questions about tasks performed, the use of specific chemicals and equipment, and the use of protective gear.

Information collected on cellular telephones will include the type(s) of phones used (hand-held, car, or transportable cellular phone), duration of use, and frequency of use. A distinction will be made between cordless phones commonly used in homes, and cellular phones, which operate at a higher frequency (800-900 mHz) and power.

Researchers will also look at family histories of brain tumors and other cancers; consumption of vitamins, fruits, vegetables; consumption of foods and beverages containing N- nitroso or related compounds; medical and dental exposures to ionizing radiation; reproductive histories; exposure to viruses; and pre-existing medical conditions. Key features of the study include its large size, the emphasis on identifying and interviewing brain tumor patients soon after diagnosis, and the use of job-specific questions developed by industrial hygienists to better ascertain occupational exposures.

The study is headed by intramural researchers at NCI and will be conducted in collaboration with investigators at participating hospitals. Contractors working under NCI supervision will do the field work and data management. Data collection will begin in May 1994 and finish by the end of 1996. Separate analyses will be conducted for different types of brain tumors, and a report on the findings should be available in 1997.

Date Last Modified: 05/94

Source: CancerNet from the National Cancer Institute
Page last updated 1/26/97

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