||5R01CA076021-02 Interpret this number
||University Of Washington
||Calcium Channel Blockers and Breast Cancer
DESCRIPTION: Approximately seven million Americans are currently using
calcium channel blockers primarily for treatment of hypertension or angina.
To date, his class of drugs has not been evaluated for long-term outcomes,
including incident heart disease and cancer. Two prospective cohort studies
of the elderly have found an association between use of calcium channel
blockers and incident cancer, one, site-specific to breast cancer (hazard
ratio=2.57, CI=1.47-4.49). The intent of this study is to examine further
the relationship between the use of calcium channel blockers and incident
breast cancer in women, aged 55-84, enrolled in the Group Health Cooperative
(GHC), an HMO based in Seattle, WA. The risk of breast cancer will be
assessed according to ever-use, dose, duration, and chemical class of
calcium channel blockers. An historical cohort design will be used to
initially examine this relationship; a nested case-control study will be
included to assess potential confounding and effect modification by other
variables. The cohort will consist of all women, aged 55-84, enrolled in
GHC on January 1, 1988 (approximately 37,300 women). The cohort will be
followed through 1996 for incident breast cancer identified through the
Cancer Surveillance System. Approximately 225 cases per year are expected.
Exposure will be assessed from the GHC computerized pharmacy database. Data
on use of other medications, pathology of the tumors, age, and inpatient
diagnoses and procedures are available to evaluate confounding and effect
modification on the cohort. A nested case-control study will supplement the
cohort analysis by assessing data not available electronically and to
determine the extent of misclassification in the cohort analyses.
Four-hundred hypertensive cases will be frequency matched to 400
hypertensive controls, for whom medical records and abstraction of the
following data will be done: age, race, parity, body mass index, smoking
history, family history of breast cancer, medication use (including
hypertensives and estrogen replacement therapy), history of previous
diagnoses of CHD, previous cardiac procedures and mammography.