Smoking Increases Risk of Breast Cancer Metastasis to Lungs
Female smokers with breast cancer may have an increased risk of their cancer spreading to the lungs compared to non-smokers, according to the results of a recent study published in the journal,
Breast cancer is the second leading cause of cancer death in women in the United States, with approximately 200,000 cases diagnosed each year. Although several risk factors have been associated with breast cancer, the cause of the majority of cases of breast cancer remains unknown. Researchers continue to explore the causes and risk factors for this disease in an effort to improve methods for screening and prevention.
Smoking has consistently been associated with several types of cancer including lung, mouth, pharynx, larynx, esophagus, pancreas, kidney and bladder. According to
Women and Smoking, a 675-page report by the surgeon general issued in March, 165,000 women died prematurely in 1997 from smoking-related diseases, including cancer. More than 90% of lung cancers result from smoking and 67,600 women died of lung cancer in 2000.
It has long been known that smoking is associated with a poorer prognosis following a breast cancer diagnosis. Recently, researchers from the University of California, Davis Medical Center conducted a case-control study to determine whether there is an association between smoking and the development of cancer spread to the lungs among women with breast cancer. The study involved 87 women with unilateral, invasive breast cancer and pulmonary metastatic disease. Each of these patients was matched with two control patients (174) who had unilateral, invasive breast cancer, but no metastases to the lungs. The two groups were then directly compared.
The results indicated that 38% of the patients whose cancer had spread to the lungs were smokers or had previously smoked, compared with 29% of patients in the control group. Furthermore, 24.1% of the women whose cancer had spread to the lungs were actively smoking at the time of their breast cancer diagnosis, compared with 15.3% of the women in the control group.
The researchers concluded that there appears to be an association between smoking and the development of lung metastases among women with breast cancer. This association might explain why smokers with breast cancer tend to have higher fatality rates.
Since smoking may increase the risk of metastases in the lungs and breast cancer commonly spreads to the lungs, current and former smokers with breast cancer or who are at a high risk for breast cancer may want to consider a smoking cessation program. Individuals concerned with screening for this disease or smoking cessation programs can consult with their physicians for more information.
(Chest, Vol. 119, pp. 1635-1640, 2001)
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