 
Passive and active smoking are both risk factors early breast cancer
Results of studies "with thorough passive smoking exposure assessment" indicate that passive smoking raises
the risk of breast cancer, especially premenopausal disease, to a similar degree as active smoking.
Dr. Kenneth C. Johnson, of the Public Health Agency of Canada, Ottawa, Ontario, examined the association
between breast cancer risk and passive and active smoking in a meta-analysis of 19 published studies that met
basic quality criteria. Results are published in the November issue of the International Journal of Cancer.
The investigator calculated pooled relative risk estimates for breast cancer for life-long non-smokers with
regular passive exposure to smoke and for women who smoked compared to women who were never regularly exposed to tobacco smoke.
Long-term regular exposure to passive smoking was associated with an overall 27% increased risk of breast cancer
among women who had never smoked.
"More importantly, among the studies that collected the most complete measures of passive smoking the observed
breast cancer risk was increased by 90%," Dr. Johnson said in an interview with Reuters Health. "Studies with less
complete second-hand smoke measures only observed an 8% increase in risk."
"The relationship with premenopausal breast cancer risk was stronger - elevated 68% with long-term regular passive
smoking exposure among life-long non-smokers based on 14 studies," Dr. Johnson explained. "The premenopausal risk was
up 119% for the five studies with more complete second-hand smoke measures."
Compared to women with neither active nor regular passive smoke exposure, those who smoked had a 46% increased risk
of breast cancer. The risk was raised 108% in studies with more complete passive exposure assessment. For studies with
less complete passive exposure assessment, the risk was increased by 15%.
Dr. Johnson noted that tobacco smoke exposure was epidemic in many developed countries for at least the last half
century. "In our Canadian breast-ETS study included in the meta-analysis, we found that more than 50% of women had
reported smoking and another 40% had had regular long-term exposure to passive smoking, either growing up with parents
who smoked, living with a spouse who smoked or working with smokers," he said.
"Luckily the landscape is changing rapidly regarding smoking in public places in North America in particular,
but there are still many children, spouses, and workers being unnecessarily exposed to tobacco smoke daily," the
investigator stressed. "It is clearly time to redouble efforts to reduce non-smokers' exposure to second-hand smoke
in all environments," he concluded.
Int J Cancer 2005;117:619-628. The above message comes from "Reuters Health", who is solely responsible for its content.
The above is for general informational purposes only. Always consult your
physician regarding specific medical issues and call Hatzalah or your local
ambulance service in the event of an emergency.
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