Exposure to Secondhand Cigarette Smoke Over a Lifetime Increased Breast Cancer Risk Later in Life

http://www.sciencedaily.com/releases/2009/12/091203090221.htm

ScienceDaily (Dec. 5, 2009) — Exposure to secondhand smoke for a prolonged period of time and in high quantity may increase the risk of breast cancer, even in women who never smoked cigarettes themselves.

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Overall, findings showed no evidence that simple measures of secondhand smoke were associated with breast cancer risk. Risk seemed to be confined to exposures experienced during adulthood (among women aged 20 or older) and primarily among those who were postmenopausal; early-life exposures (before the age of 20) did not alone appear to increase their risk.

Women exposed to moderate to high levels for a combination of years and intensity of exposure had a significant dose response so that the risks for developing breast cancer increased as the cumulative exposure levels increased, according to Reynolds.

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