Is Smoking a Risk Factor of Breast Cancer?

Abstract

The incidence of breast cancer is increasing worldwide, making it the most common cancer among women. The etiology of breast cancer is multifactorial, including genetic risk factors, family history, age, gender, ethnicity, dense breast tissue and life-style related risk factors. Cigarette smoking is one of the risk factors in many cancers and recently been shown to be associated with breast cancer. The relationship between cigarette smoking and breast cancer has been explored in vitro and in vivo. One of the important components of cigarette smoke, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a representative carcinogen of N-nitrosamines, has also gained focus in breast cancer carcinogenesis. Other than promoting tumor growth in cancer cells, NNK has also been proved to cause malignant transformation in normal breast cells. However, clinical association of NNK and breast cells is still limited, and there are controversies that warrant further explorations