An evaluation of the lifestyle habits of more than 13,000 healthy women with a high risk of breast cancer showed that the risk of breast, lung, and colon cancers is higher for women who have smoked for a long time, compared with women who did not smoke or who smoked for a shorter time.
The women who participated in this study had an increased risk of breast cancer, which was determined by age, a diagnosis of lobular carcinoma in situ (LCIS; not cancer but considered a risk factor for cancer), and a family history of breast cancer, as well as other factors.
When compared with women who did not smoke, the study showed the following risks for women who smoked:
- Women who had smoked for at least 35 years were 60% more likely to develop breast cancer and more than four times likely to develop colon cancer.
- Women who had smoked between 15 and 35 years were 34% more likely to develop breast cancer and 7% more likely to develop colon cancer.
- Women who smoked more than one pack of cigarettes per day for more than 35 years were 30 times more likely to develop lung cancer.
- Women who smoked less than one pack of cigarettes per day for more than 35 years were 13 times more likely to develop lung cancer.
Researchers also looked at how other lifestyle factors affect cancer risk. They found that low levels of physical activity were associated with a higher risk of uterine cancer, which may have been from the association of low fitness levels and obesity (also a risk factor for uterine cancer). The study also showed that moderate alcohol use did not increase cancer risk and may have decreased the risk of colon cancer.
What this means for patients
“This study showed an even greater increase in risk of cancer from smoking than has been shown in previous studies, suggesting that for women who are at risk of breast cancer because of family history or other factors, smoking cigarettes is even riskier than for other women. It sends a very important message about the long-term risks of smoking, as well as the importance of staying physically active. We're seeing again that quitting smoking is one of the most effective tools we have for reducing risk of many cancers,” said lead author Stephanie Land, PhD, Research Associate Professor in the Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh.
Questions to ask your doctor
- What is my risk of cancer?
- How does smoking affect my risk of cancer?
- Could you recommend resources to help me quit smoking?
- What else can I do to lower my risk of cancer?
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