RISK AND RISK REDUCTION > Established risk factors >
Tobacco smoke
ESTABLISHED RISK FACTORS
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NON-MODIFIABLE RISK FACTORS |
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MODIFIABLE RISK FACTORS |
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TOBACCO SMOKE
The weight of recent evidence on smoking and young women points to an increased breast cancer risk for women who begin smoking or are exposed to second-hand smoke starting in adolescence and before carrying a full-term pregnancy.
Adolescence is a period of rapid development for the breasts, and it is believed that during this time the breasts may be more susceptible to cancer-causing agents. Full development of the breast tissue takes place after a first full-term pregnancy, when hormones cause breast tissue to mature in a way that seems to protect against the effects of some cancer-causing agents, possibly including the effects of tobacco smoke.
Research evidence on smoking and breast cancer risk is inconclusive for women who start smoking or who are exposed to smoke later in life or after their first full-term pregnancy.
There are a number of possible reasons for not having a clear answer on tobacco smoke and breast cancer risk for women across the life cycle:
- Research studies differ in many ways, such as the groups of women being studied, how information is collected and what other risk factors are taken into account. Since smoking is related to some of the established risk factors for breast cancer, such as alcohol use and having given birth, the ways in which these types of factors are taken into account or not in research studies can affect the findings.
- Exposure to tobacco smoke may affect breast tissue differently depending on what stage of development the tissue is in.
- Tobacco smoke may interfere with the production of estrogen outside the ovaries. This effect on estrogen could compete with the carcinogenic (cancer-causing) effect of smoking for postmenopausal women in particular. This is because postmenopausal women have lower overall levels of estrogen and produce most of their estrogen in fat and other tissues outside the ovaries.
There is ongoing research to try to determine the link between tobacco smoke and breast cancer risk for women of all ages.
For women of all ages there are many benefits to not smoking, regardless of any connection to breast cancer risk. Smoking is associated with higher risk for other conditions, such as heart disease, lung cancer, and other cancers. Reducing or eliminating your exposure to active and passive smoke offers a number of health benefits with regard to blood pressure, circulation, lung function, reproduction, and lower risk for a number of diseases.
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