NCCC's study data on passive smoking and breast cancer in women

The American Association for Cancer Research (AACR) released findings today from one of the largest studies to date on passive smoking and breast cancer in women conducted by the Northern California Cancer Center (NCCC).

Study data revealed that women who never smoked cigarettes and who were exposed to secondhand cigarette smoke over a lifetime--especially during adulthood--had a significantly increased breast cancer risk later in life.

Breast cancer risk increased with higher levels of exposure, and postmenopausal women with exposures at or after age 20 had the greatest risk increase at 25%.

The findings, that were published in the December issue of the AACR journal, Cancer Epidemiology, Biomarkers & Prevention, provide additional evidence for public health risks from secondhand smoke exposure.

Data for this study consisted of detailed information from questionnaires filled out by more than 57,000 women in the ongoing California Teachers Study, which has examined lifestyle, medical history and women's health since it began in 1995.

"Our study is one of the largest of its kind and had some of the most detailed measures of passive smoking of any study to date," said NCCC Senior Research Scientist Peggy Reynolds, Ph.D., who directed the study. "Because the California Teachers Study has extensive information on known risk factors for breast cancer, we could rigorously assess the impact of passive smoking, independent of those factors."

In the 12 years since the initial questionnaires were completed, 1,754 newly diagnosed cases of invasive breast cancer occurred in teachers participating in the study.

Based on the findings, Dr. Reynolds suggests more research is needed to better assess overall secondhand smoke exposure patterns.

SOURCE Northern California Cancer Center