Breast cancer is the most prevalent cancer and the leading cause of cancer-related mortality among women around the world.
Smoking is one of the ten main risk factors for cancer and researchers have been investigating the association between breast cancer and smoking for more than two decades. In one study, Reynolds et al., after surveying 116544 women, found that the risk of breast cancer in smokers was bigger, that confirmed the role of smoking in the etiology of this cancer. They have shown that the risk of breast cancer in smokers is higher than non-smokers and those who were exposed to second-hand smoke. The risk is higher for whom that had started smoking at least 5 years before their first pregnancy.
Other studies have also suggested that the risk of breast cancer in women exposed to smoking during childhood and adolescence is increased. According to the study, exposure to early smoking, especially before pregnancy, can lead to breast cancer.
In another study performed by the American Cancer Society with about 6000 women, they have found that the mortality rate caused by breast cancer is much higher in smokers than non-smokers.
Although in Iran, only a small number of women are smokers, smoking by men exposed women and children to second and third-hand smoke.