A new study shows smoking increases the risk of breast cancer in post-menopausal women.
Almost 80,000 women participated in the study, including 5,000 from Minnesota.
The risk was highest among current smokers who had smoked a lot over a long period of time. It was also higher among women who began smoking in their teens or before their first full-term pregnancy.
Dr. Karen Margolis, from the HealthPartners Research Foundation and the senior author of the paper, said the findings add to the list of reasons to quit smoking.
"For some people they may want to stop because of ill effects on their family members. Some people may be more worried about heart disease. Some people may be more worried about lung cancer," she said. "And for some people hearing about the increased risk of breast cancer may just be the straw that breaks the camel's back and gets them to quit."
The study also found that extensive exposure to second-hand smoke leads to an increased risk of breast cancer, though Margolis says more research on that link is needed.