There is more evidence that cigarette smoking is associated with breast cancer. The strongest associations may be among women who take up the habit during adolescence or prior to the start of menses.
Smoking and risk of breast cancer in the Generations Study cohort
Authors: Jones, M.E. et al.
Source: Breast Cancer Research (2017) 19:118
Cigarette smoke is a known cause of many types of cancer. The association between smoking and breast cancer is strongly suspected but not consistently proven in the scientific literature. This group tried to determine a link between the habit and the disease.
The Generations Study began in the United Kingdom in 2003. Women aged 16 and older were invited to participate. They were given questionnaires over a 9½ year period, and answered questions about their health and lifestyle habits, including cigarette smoking. Diagnosis of breast cancer was identified in the questionnaire responses as well as in the nation’s national health database. Over 102,000 women participated in this project.
The investigators found that a history of cigarette smoking increased the risk of breast cancer and the risk climbed with the number of cigarettes smoked per day. The risk of the disease rose with each year of smoking up to 10 years. Smoking habits for longer than 10 years did not lead to greater risks of breast cancer. Breast cancer risk continued to be elevated for the first 20 years after smoking cessation.
Age played a significant role. Breast cancer risk was increased if women began smoking younger than age 17 or between 17 and 19. The risk of breast cancer was not affected when women began smoking at older ages. The risk of breast cancer with smoking was greatest if the habit began before the start of menses (menarche).
The investigators note that the number of smokers and the number of breast cancer cases in the study were low. More trends or greater significance may be seen with a higher number of participants. Nonetheless, this study shows that there is a real association between cigarette smoking and breast cancer, and suggests that the association may be strongest when women begin to smoke prior to menarche.