Tobacco smoke is unquestionably the single greatest cause of preventable cancer cases. However, the link between smoking (including passive exposure to secondhand tobacco smoke) and breast cancer has been rather unclear, so far. Now, a newly published study, which appears in the current issue of the British Medical Journal, has strongly linked exposure to tobacco smoke with breast cancer risk.
More than 79,000 women (ages 50 to 79 years) enrolled in the enormous landmark, prospective Women’s Health Initiative (WHI) study between 1993 and 1998. (This is the very same study that confirmed the long suspected link between hormone replacement therapy and breast cancer risk.) All participants in this huge clinical study provided detailed information regarding their history of both active and passive exposure to tobacco smoke. Known risk factors for breast cancer were also assessed, and accounted for, when analyzing this study’s data. During more than 10 years of follow-up, 3,520 cases of breast cancer were diagnosed within this very large group of women.
Compared with women who had never smoked, former smokers were9 percent more likely to be diagnosed with breast cancer, while current active smokers were 16 percent more likely than never-smokers to develop breast cancer. Women who had smoked for 50 years or more were at especially high risk of developing breast cancer (they were 35 percent more likely to be diagnosed with breast cancer when compared to never-smokers ).
Among women who had never smoked, women with 10 or more years of childhood exposure to secondhand tobacco smoke, or 20 or more years exposure as an adult, had a 32 percent greater risk of developing breast cancer than never-smokers who had not been exposed to secondhand tobacco smoke.
Taken together, these new findings from the powerful WHI study significantly link both active exposure to tobacco smoke and exposure to secondhand tobacco smoke with large increases in the risk of developing breast cancer. As if there were not already enough reasons to avoid tobacco, this very powerful prospective clinical research study’s findings confirm yet another life-threatening risk associated with tobacco (including exposure to secondhand smoke).
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