interview: use of electric bedding devices (electric blanket, electric mattress pad, or heated water bed), number of years of use, number of months of use per year, and mode of use (whether the device was left turned on most of the time during sleeping or was used only to warm the bed)
An increased risk for breast cancer was observed for women who used an electric bedding device (group 2) as compared to the reference group 1 (OR 1.4, CI 0.9-2.2). The risk increased with increasing number of years of use (use for more than 10 years: OR 4.9, CI 1.5-15.6). The risk appeared to be higher for use in more than 3 months per year as compared with use in 3 months or less (OR 1.7, CI 0.9-3.2). No risk was observed for using the device for warming the bed only (group 11: OR 1.0, CI 0.5-2.2), however an increased risk was found for keeping the device on most of the time (group 12: OR 1.7, CI 1.0-3.0). Restricting the analyses to women who presumably used an electric blanket, the corresponding dose-response relations were more striking. Similar results were found for both premenopausal and postmenopausal women and for both estrogenreceptor-positive and estrogenreceptor-negative tumors. The authors conclude that the use of electric bedding devices may increase breast cancerrisk in African-American women.