Are Women at Increased Risk for Developing Lung Cancer?
Some studies suggest that women are more susceptible to the carcinogens in cigarettes and develop lung cancer after fewer years of smoking. In a case–control study of 14,596 patients who had lung cancer, the relative odds ratio (OR) for developing lung cancer was higher in women than in men: 12.7 and 9.1, respectively. Risch and colleagues studied the male–female differences in cigarette smoking in over 800 Canadian patients with lung cancer. They found a higher OR for lung cancer for female smokers of 27.9 compared with 9.6 for male smokers. A hospital-based case–control study of 1889 subjects who had lung cancer (1108 men and 781 women) and 2070 control subjects who had diseases unrelated to smoking revealed that women who had lung cancer had less exposure to cigarette smoke than men who had lung cancer, they were more likely to be never-smokers, started smoking at a later age, smoked fewer cigarettes, and smoked brands that contained less tar. Despite this, women had approximately a 1.2–1.7-fold higher risk for developing lung cancer than men did. Finally, a study of computed tomography (CT) screening in 14,435 persons (6296 women and 8139 men) at risk for lung cancer (more than 40 years of age and greater than 20-pack year smoking history) reported that lung cancer was diagnosed in 156 women and 113 men (rates of 2.1 and 1.2% respectively). The prevalence OR comparing women with men was 1.9 after adjusting for age and smoking history.
By contrast, several other case–control studies that have also explored this issue have not substantiated the idea that an excess risk for lung cancer exists in women. A large study found no difference in susceptibility between males and females, despite a detailed correction for the amount of cigarette exposure. The American Cancer Society follow-up prevention study, which enrolled 1.2 million men and women, showed that while the overall risk of lung cancer in women had increased to 11.9, men who smoked had a greater relative risk for developing lung cancer (22.3). Bach and colleagues analyzed data on 18,172 subjects enrolled in a large randomized trial of lung cancer prevention and concluded that the risk of lung cancer varied widely among smokers. The authors did not find a convincing association between sex and lung cancer risk. In addition, a recent analysis of cohort data from the Nurses' Health Study of women and the Health Professionals' Follow-up Study of men failed to find a difference in lung cancer risk between the sexes.
Despite the controversy regarding the risk of lung cancer between males and females, there is considerable evidence that the biology of lung cancer differs between the sexes. When observational studies present a new finding, possible biological explanations for the findings are then explored. Several explanations for the sex differences in lung cancer have been studied and include differences in molecular abnormalities, growth factor receptors, hormonal influences, differences in cytochrome P450 enzymes and differences in DNA repair capacity.
Expert Rev Resp Med. 2009;3(6):627-634. © 2009
Cite this: Lung Cancer in Women: The Differences in Epidemiology, Biology and Treatment Outcomes - Medscape - Dec 01, 2009.