The use of complementary and alternative medical providers by insured cancer patients in Washington State. BACKGROUND: Insurance coverage of complementary and alternative medicine (CAM) is expanding. However, to the authors' knowledge, little is know concerning CAM utilization among cancer patients under the insurance model of financing. In this study, the authors evaluated CAM provider utilization by cancer patients in a state that requires the inclusion of alternative practitioners in private, commercial insurance products. METHODS: An analysis was carried out of year 2000 claims data from two large Washington State insurance companies.