Summary, Conclusions, and Plans
This study was undertaken in response to concerns about increased rates of brain cancer in a six-county area in Idaho. Analysis had revealed that 182 cases of brain cancer were reported in the six-county area from 1975 to 1994, in contrast to 152 cases expected during the same time period based on the rate in the remainder of Idaho. Following is a brief summary of the findings, conclusions, and our future plans.
The majority of respondents indicated they were white, and non-Hispanic.
Age of those diagnosed with brain cancer ranged from 2 - 86.
Sixteen percent of respondents had another relative with brain cancer, and 48% of respondents had a relative with some type of cancer other than brain or skin cancer.
Home pesticide use varied widely among respondents, from daily to never, but some persons also reported exposure to crop dusting chemicals which is difficult to quantify. Job chemical exposure was reported by 36% of respondents. When specific chemicals were named, the type of chemical varied greatly among respondents. Sixteen percent of respondents reported some type of radiation exposure at work, and one person may have been exposed to frequent medical radiation prior to brain cancer diagnosis.
Exposure to fumes, vapors or dusts at work were reported by 34% of respondents, but the types of specific exposures reported varied widely.
Military experience was reported by 27% of adults, but the type and location of military experience was not the same among most respondents.
Among children, age of diagnosis varied greatly. Residence and school attendance included 4 of the 6 counties; no children were living in Butte or Clark Counties at diagnosis. Two of the children were very young at diagnosis, suggesting that they may have been born with brain cancer.
Hobbies involving possible exposure to chemicals were reported by 25% of respondents; the most common hobby reported was painting.
Upon reviewing the results, we found that a wide variety of life experiences, occupations, and exposures were represented. No common factors were identified that clearly linked the cases, and individuals expressed varying concerns about possible exposures or causes for brain cancer.
The survey was designed by members of the Cluster Analysis Work Group at the Idaho Department of Health and Welfare and the Cancer Data Registry of Idaho (CDRI) to gather more information about possible exposures among persons with brain cancer in the area with elevated rates. The survey was not designed to investigate causes of individual cases of brain cancer, or to compare exposures and behaviors among residents of the area with brain cancer to residents of the area without brain cancer.
The results of this survey will be shared with other members of the public health community with particular expertise in brain cancer investigations. We anticipate guidance from them on whether further investigation is likely to be helpful in determining a possible cause for the elevated rates of brain cancer in the area. Further, the CDRI will continue to collect information on the numbers and types of brain cancer throughout the state and the survey area, and the data will continue to be analyzed for trends.
This report will be made available to persons interested in brain cancer, including educators, researchers, scientists, and the media, after those involved in the survey have had the opportunity to review and comment on it. Questions and comments are welcomed and should be addressed to:
Christine Hahn, MD
State Epidemiologist
Idaho Department of Health and Welfare
450 W. State St.
Boise, Idaho 83720-0036
Ph 208-334-5939