American Cancer Society Study Finds No Association Between Exposure to Environmental Tobacco Smoke and Breast Cancer Mortality

American Cancer Society
Friday, 1 June 2001

A study of nearly 150,000 never-smoking women found no association between exposure to environmental tobacco smoke (ETS) and breast cancer mortality, reports a team of researchers from the American Cancer Society, the UMDNJ-Robert Wood Johnson Medical School, and the U.S. Environmental Protection Agency. These results disagree with previous studies that reported an increase in breast cancer risk among women exposed to ETS. However, the prospective design, the large number of women involved, and the reporting of ETS by both spouses give credence to the current study.

The study followed a group of 146,488 never-smoking married women who were cancer free at study entry in 1982. After 12 years of follow-up, 669 deaths due to breast cancer were observed in this group of women. The primary analyses defined exposure to ETS as active smoking by the husband as reported in his questionnaire, and considered both amount and duration of spousal smoking. A second definition of ETS exposure was derived directly from each woman's report of the number of hours per day that she was "exposed to the smoke of others" at home, at work, and elsewhere.

No association between ETS and death from breast cancer was found in this analysis regardless of the number of packs of cigarettes smoked per day by the husband or the years that he had smoked. A small, but not statistically significant, increase in mortality was found among women married to current smokers before age 20.

"Our results suggest that among never smoking women who have been exposed to the passive smoke of their husbands for 30 or more years, there is no increase in their risk of dying of breast cancer", said Dr. Eugenia Calle, Director of Analytic Epidemiology, of the American Cancer Society. "It's important to understand the causes of breast cancer, and since the potential population of women exposed to ETS is large, this analysis represents a significant contribution to the study of this association."

"While the link of ETS to breast cancer risk or mortality has not been truly established, ETS is a well-proven serious health danger," said Harmon J. Eyre, MD, Chief Medical Officer of the American Cancer Society. "Efforts to protect men, women and especially children from exposure to ETS should be strongly supported," he added.

The study is published in the October 18 issue of the Journal of the National Cancer Institute.

The landmark American Cancer Society Cancer Prevention Study II, begun in 1982, has also provided a wealth of data about active smoking as well as information about the impact of ETS on mortality from lung cancer and coronary heart disease.

The American Cancer Society is the nationwide community-based voluntary health organization dedicated to eliminating cancer as a major health problem by preventing cancer, saving lives and diminishing suffering cancer through research, education, advocacy, and service.

For more information, or to contact American Cancer Society, see their website at: www.cancer.org