DeRoo LA, Cummings P, Mueller BA.
Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
Am J Epidemiol 2011;174:390–402.
Editor’s note: Although the association between smoking and breast cancer is still contested, it is possible that smoking during susceptible periods may increase risk. According to studies on breast development and cancer susceptibility, the relatively undifferentiated breast epithelial cells present before a first pregnancy may be particularly vulnerable to the carcinogenic effects of cigarette smoke. The current authors conducted a meta-analysis of the association between smoking before a first pregnancy and the risk of breast cancer.