Researchers from the American Cancer Society and the National Cancer Institute have found rates of lung cancer are higher in women than men among white and Hispanic people born since 1965. Lead author of the study, Ahmedin Jemal, DVM, PhD, says he was surprised by the findings because historically, lung cancer rates have been higher in men. Another surprise, said Jemal, is that differences in smoking patterns cannot fully account for the change.
The study was published May 23, 2018 in the New England Journal of Medicine.
Historically, women in the US were less likely to smoke, started smoking at older ages, and smoked fewer cigarettes per day than men. They also have had lower rates of lung cancer incidence and death. However, smoking behaviors have become increasingly similar between men and women. Overall, white women born in the 1960s and early 1970s tend to smoke as much as, or more than men.
Jemal and his colleagues looked at data from the North American Association of Central Cancer Registries and analyzed cases of lung cancer diagnosed in people ages 30 to 54 from 1995 to 2014 in the US. They found lung cancer decreased for each age group, but declined more for men. The result is that lung cancer incidence rates are now higher for white women and Hispanic women born since the mid-1960s.
For example, rates of lung cancer among white women ages 40-44 went from 12% lower than men during the 1995-1999 period to 17% higher during the 2010-2014 period. Rates also crossed over from being higher among men to being higher among women for Hispanic women in some age groups. Among black and Asian women rates got closer to the rates for men, but rates of women’s lung cancer incidence rates did not exceed those of men for those ethnic groups.
Interestingly, the researchers found that smoking patterns among women did not fully explain the change in lung cancer incidence rates. “While prevalence of smoking among men and women has converged over the past several decades, smoking prevalence among women has still generally not exceeded that of men,” said Jemal. “We do not believe sex differences in smoking behavior explain our finding of a gender crossover. For example: the crossover also occurred among Hispanics, even though smoking continues to be less common in young Hispanic women than young Hispanic men.”
The authors say more research is needed to understand what is causing the higher rates of lung cancer among young women. They speculate women may be more susceptible than men to the health hazards of cigarette smoking. Another possibility is that women may be more likely than men to get lung cancer even after quitting smoking.
Jemal says the findings are an opportunity for the public health community to not only do more research into gender-specific risks of lung cancer, but also to increase efforts to decrease smoking among young women. He points out that even though services to help people quit smoking, including counseling and medication, have been shown to be effective, only 1/3 of smokers who try to quit seek out those services. “Quitting at any age is beneficial,” said Jemal. “But if you quit at a younger age, you remove most of the excess risk of lung cancer and other smoking-related diseases associated with smoking.”
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Higher Lung Cancer Incidence in Young Women Than Young Men in the United States. Published May 23, 2018 in the New England Journal of Medicine. First author Ahmedin Jemal, DVM, PhD, American Cancer Society, Atlanta, Ga.