175 Views Posted on 03-Mar-2011 under Health

Women who smoke regularly before their menopause have a higher risk of developing lung cancer - the risk is even higher before they get pregnant, researchers from Brigham and Woman's Hospital and Harvard Medical School wrote in Archives of Internal Medicine. No link was found among light smokers.
The authors explained that breast cancer is the most common female cancer globally. Potential carcinogens in tobacco smoke, such as N-nitrosamines, aromatic amines, and polycyclic aromatic hydrocarbons can raise risk of developing breast cancer.
The scientists gathered data from the Nurses' Health Study, including the medical records of 111,140 active smoking females from 1976-2006, as well as 36,017 women who inhaled secondhand smoke from 1982-2006. Second hand smoke inhalation is also referred to as passive smoke (passive smoking) or environmental tobacco smoke.
During follow-up they identified 8,772 cases of breast cancer diagnoses. There was a clear link between current/past smoking and breast cancer risk. The risk was also greater if the woman smoked for longer, started at an earlier age, and consumed many cigarettes each day.
"Smoking before menopause was positively associated with breast cancer risk, and there were hints from our results that smoking after menopause might be associated with a slightly decreased breast cancer risk. This difference suggests an antiestrogenic effect of smoking among postmenopausal women that may further reduce their already low endogenous estrogen levels."
On the other hand, no association was found between adult or childhood passive smoking and a higher breast cancer risk. The researchers looked into all cases where the female has been subjected to passive smoking as a child at home, and as an adult at home or at work. Even when exposure went on for a very long time, no link was found.
"In the present study, we created an index of active smoking that integrates quantity, age at which one started smoking and duration of smoking. The results suggested that, although an elevated risk for light smokers and moderate smokers was not apparent, heavy smokers who started smoking early in life, smoked for a long duration and smoked a high quantity were at the highest risk of breast cancer, supporting an independent and additive effect from various smoking measures on breast carcinogenesis."