Smoking
Does cigarette smoking increase my risk of breast cancer?
When all factors related to breast cancer are taken into account, all studies agree that any differences in the risk of breast cancer between smokers and nonsmokers are very small. It is interesting to note that some evidence indicates that smoking protects against breast cancer. However, this is not a reason to start smoking. Approximately 99% of the breast cancers that are detected very early are treated successfully. In contrast, lung cancers are rarely treated successfully.
What is the research on smoking and breast cancer?
Most early studies of the health effects of smoking made the interesting discovery that smokers had breast cancer 15–25% less frequently than nonsmokers. In theory, a protective effect of smoking is possible, because nicotine suppresses the amount of estrogen (female sex hormone) in the blood. This is one reason why women who smoke often develop facial wrinkles earlier than nonsmokers and, on average, reach menopause two years earlier. Among the tiny fraction of women whose risk of breast cancer is high because of genetic mutations on the BRCA1 and BRCA2 genes, those with a history of smoking develop breast cancer around half as often as those who are lifelong nonsmokers.
How could smoking possibly reduce the risk of breast cancer?
Recent research on the metabolism of estrogens shows that smoking is connected to how the body processes estrone, the most common circulating estrogen. The estrones in the blood of smokers are more likely to become less active and to promote less growth in the cells of the breast tissue than are the estrones in the blood of nonsmokers. For this reason, smokers may be at a lower risk of breast cancer, but they are at a very high risk of developing lung cancer and a variety of respiratory conditions.
