According to results recently published in the International Journal of Cancer, smoking significantly increases the risk of developing breast cancer in premenopausal women.
Breast cancer is diagnosed in approximately 200,000 women annually in the United States. Due to its high prevalence, particularly in the United States and Western countries, researchers are trying to determine environmental factors that may be attributable to the development of breast cancer. Individuals exposed to environmental factors that may increase their risk of cancer may choose to alter their lifestyles to reduce their risk or to undergo more rigorous screening to detect and treat the cancer as early as possible. Results from large studies have indicated that smoking may be associated with the development of lung cancer, bladder cancer, head and neck cancer, and possibly other types of cancer. Research is ongoing to uncover possible associations between smoking and additional types of cancer or other diseases.
Patients associated with the National Cancer Center in Japan recently conducted a clinical study to further evaluate a possible association between smoking and breast cancer. This study included over 21,000 women who were between the ages of 40 and 59 years in the year 1990. By 1999, 180 women had developed breast cancer. Among the study participants, nearly 93% had never smoked, 5.7% were current smokers, and 1.7% were ex-smokers. Overall, the risk of developing breast cancer in premenopausal women was increased nearly 4 times in women who had ever been smokers, compared to those who had never smoked. Exposure to second-hand smoke, or passive smoke, also increased the risk of developing breast cancer in premenopausal women. The rates of developing breast cancer in postmenopausal women did not seem to be significantly affected by smoking.
The researchers concluded that smoking, both active and passive, increases the risk of developing breast cancer in premenopausal women. These results provide further evidence as to the importance of smoking cessation, particularly as breast cancer in premenopausal women has a significantly worse prognosis than the disease in postmenopausal women.
Reference: Hanaoka T, Yamamoto S, Sobue T, et al. Active and passive smoking and breast cancer risk in middle-aged Japanese women. International Journal of Cancer. 2005; 114:317-322.