A new study recently published in Cancer Causes and Control by investigators from the Slone Epidemiology Center at Boston University, adds further evidence about the adverse effects of cigarette smoking on health. The researchers found that both active and passive smoking were associated with an increased risk of breast cancer in African-American women.
The data was collected during 14 years of follow-up among participants in the Black Women’s Health Study, a study of 59,000 African-American women that began in 1995. The participants updated information on their smoking habits throughout follow-up and also provided information on their exposure to the smoke of others (passive smoking). During follow-up for the present research, 1,377 women were diagnosed with breast cancer. Among women who began smoking earliest and smoked most heavily, the incidence of premenopausal breast cancer increased by 70 percent. The associations were most apparent for estrogen receptor positive breast cancer. Passive smoking was associated with a 40 percent increase in risk of premenopausal breast cancer.
According to the researchers, the earliest studies of the health effects of smoking did not find an increased risk of breast cancer, probably because in those early years there were few long-term smokers. In recent years, studies of smoking and breast cancer have more consistently found an increased risk among women who smoked heavily for many years. Lynn Rosenberg, ScD, lead author of the study, believes that the evidence is now clear that smoking increases the risk of breast cancer. “What remains to be determined is whether there are particular times during life that smoking is particularly hazardous, such as before the first pregnancy, and whether there are particular groups of women who are especially vulnerable,” she said.
Funding for this study was provided by the National Cancer Institute.