In addition, researchers found strong evidence that passive smoking heightened the threat of breast cancer in women who had never smoked but were exposed to excessive environmental tobacco smoke as kids or as adults.

Link between smoking and breast cancer explored
In order to explore the link between smoking, passive smoking, and breast cancer, Dr Juhua Luo from West Virginia University and Dr Karen Margolis from the HealthPartners Research Foundation in Minneapolis carried out a large scale study.

For the purpose of the study, they analyzed the data of around 80,000 women, aged between 50 and 79 years from 40 health facilities across the United States.