Second hand smoke doubles breast cancer risk, study
TORONTO, March 15 (Reuters) - Premenopausal women exposed to second hand smoke are twice as likely to be diagnosed with breast cancer, said a Canadian government study on Wednesday.
``The longer the exposure, the higher the risk,'' said a Health Canada study, Passive and Active Smoking and Breast Cancer Risk in Canada, published on Wednesday in the scientific journal Cancer Causes and Control.
The study compared 1,420 women diagnosed with breast cancer to a similar number without cancer and found long-term exposure to second-hand smoke doubled the risk of breast cancer.
In post-menopausal women, the study concluded that the risk of breast cancer increased by 30 percent.
``While a study of this nature cannot confirm a causal relationship of second-hand smoke to breast cancer, it can contribute to the identification of important associations,'' said Health Canada.
The study's lead epidemiologist, Dr. Kenneth Johnson, said that although this study only shows an association between passive smoking and breast cancer, rather than proving causation, a ``strong and consistent'' association has been shown in 6 other studies.
``If our study was just a lone study and we found these kinds of results we wouldn't be presenting them in such an enthusiastic manner. But there have been six other studies done on passive smoking and breast cancer and all of them have a suggestion of increased risk,'' said Johnson.
In the 1980s studies were done that looked into the link between smoking and breast cancer and the results showed no association, said Johnson.
But Johnson points out that those researchers didn't ask about passive smoking, and therefore were comparing a smoking population to what they believed were a non-smoke infected population.
``So this results in a lot of tension in the epidemiologist community. Because a lot of very good epidemiologists did these original studies, and they have in their heads there isn't a relationship. But data talks,'' Johnson said.
Smoking and its related risks have been a hot subject as of late in Canada.
The Government of Ontario recently filed a racketeering suit against an international group of major tobacco companies to recoup tobacco-related health care costs.
The suit alleges that at least 8 tobacco companies and the Canadian Tobacco Manufacturers Council hid and manipulated information about the hazards of smoking.