Citizen requests led to the evaluation of brain cancer rates in eastern Idaho. Results of the evaluation revealed an elevated rate of brain cancer in the six-county area of Bingham, Bonneville, Butte, Clark, Jefferson, and Madison Counties compared to the rest of the state for the period 1985 through 1994. In response to the elevated rate in the six-county area, an investigation by the Cluster Analysis Work Group (CAWG) was undertaken in May 1997.


Persons diagnosed with brain cancer during 1978* through 1996 who were residing in Bingham, Bonneville, Butte, Clark, Jefferson, or Madison counties at the time of their diagnosis were identified through the Cancer Data Registry of Idaho (CDRI).

Using the registry, 180 eligible participants were identified; addresses for them or their next-of-kin were available for 108. Of the 108 surveys sent, 14 of these were returned as undeliverable to the address; therefore, 94 surveys were successfully delivered.

Response rate:

Fifty-six of 94 (60% of successfully delivered) surveys were received back from study participants or their next-of-kin.

County of residence of brain cancer patients at diagnosis:

County Number of persons
with brain cancer
listed in CDRI
Number of persons
responding to survey
Bingham 48 17
Bonneville 97 28
Butte 3 0
Clark 2 0
Jefferson 17 6
Madison 13 4
Bannock n/a 1**
Total 180 56
**Residence listed in study area in the CDRI, but self-reported Bannock County on survey.

*The first year complete and reliable information was available from the CDRI.


Note: Data on the following pages are based only on surveys that were completed and returned; no data are presented on persons who did not respond. All results such as residence and exposures refer to the peron with brain cancer, who was not always the person who actually completed the survey.

Comments / Additional Remarks

Summary / Conclusion