More Evidence Smoking Linked to Breast Cancer
NEW YORK (Reuters Health) - Women who smoke or who are exposed to secondhand smoke may have an elevated risk of breast cancer, a new report suggests.
The findings support those of previous studies, including a report released on Friday showing that girls who begin smoking as teens may be more susceptible to breast cancer later in life. Another recent report linked heavy smoking with breast cancer risk.
In the new study, current smokers were 50% more likely to be diagnosed with breast cancer compared with women who had never smoked and were not exposed to passive smoke, while former smokers were 20% more likely to be diagnosed, the investigators found.
Likewise, women who reported that they had never smoked but that they were exposed to cigarette smoke for more than an hour a day for at least a year were 60% more likely to have breast cancer, report researchers in the October 1st issue of the American Journal of Epidemiology. But if this exposure occurred during childhood or before a woman's first pregnancy, it did not appear to increase her breast cancer risk.
The researchers also found that breast cancer risk rose in tandem with the number of years a woman smoked and decreased after she quit.
In the study, the researchers reviewed medical data from 468 mostly premenopausal women who had been diagnosed with breast cancer by age 50 and more than 1,000 healthy women.
At this point, it is not clear how cigarettes affect breast cancer risk. There is some evidence that tobacco smoke contains potential human breast cancer-causing agents, but studies have often failed to demonstrate a clear link between breast cancer and smoking.
Whatever the mechanism, the findings "are of a high priority for public health recommendations" since rates of smoking and exposure to cigarette smoke are high, Drs. Silke Kropp and Jenny Chang-Claude from the German Cancer Research Center in Heidelberg conclude.