A 35-year-old woman presents to her family physician complaining of cough with sputum every morning for the past year. She reports that she’s otherwise healthy and active, but has smoked a pack of cigarettes a day for 20 years for weight control and socializing. She adds, “My grandfather died of lung cancer, but I’ve always thought that only old men get it. Do I need to worry about getting lung cancer too?”
Lung cancer is the leading cause of preventable cancer deaths in the U.S., and cigarette smoking contributes to about 80% of those deaths. Historically, men were more likely than women to get lung cancer because they were more likely to smoke, started smoking earlier, and smoked more cigarettes per day. However, changes in cultural norms have shifted women’s smoking patterns, making it necessary to examine changes in gender-related trends in lung cancer.
In this week’s issue of NEJM, Jemal et al. used data from the North American Association of Central Cancer Registries to assess U.S. population-based lung cancer trends and calculate female-to-male lung cancer incidence rate ratios (IRRs). They also examined cigarette smoking trends using data from the National Health Interview Survey.
During the past 2 decades, age-specific lung cancer incidence decreased in both men and women ages 30-54 years, but the declines were steeper in men. Consequently, the female-to-male lung cancer IRRs increased. By the final period analyzed (2010-2014), lung cancer incidence in women aged 30-49 exceeded that of men. Trends differed by racial/ethnic background and birth cohort, such that lung cancer incidence increased in white and Hispanic women born after 1950 and was greater than in men for those born after 1965. For example, the female-to-male lung cancer IRR among whites aged 40-44 increased from 0.88 during in 1995-1999 to 1.17 in 2010-2014.
The prevalence of smoking during the 1900s steadily declined in men, but increased dramatically (from 20% to 40%-50%) among white and black women before rates started falling in the 1940s in white women and in the 1950s-1960s in black women. Among women born after 1965, smoking rates were similar to those of men.
The authors concluded that the historical pattern of a higher incidence of lung cancer in men than women has reversed among white and Hispanic women born since the mid-1960s. These women now have a higher incidence of lung cancer that is only partially explained by smoking patterns. Combined with the higher rates of nontobacco-related lung cancer in women, these results suggest the need to further examine the causes of excess lung cancer risk in women and the social and economic factors that have driven increased smoking rates among young women. Such factors include tobacco industry advertising that encourages women to smoke as a demonstration of modernity, independence, assertiveness, and equality with men; and to remain slender by using smoking as an appetite suppressant amidst the modern obesity epidemic. Public health advocates must continue widespread antismoking and healthy-weight messaging, especially for young women, and work to strengthen regulations to prevent the advertising and sale of cigarettes and other addictive tobacco products to youth.
Returning to the 35-year-old patient, after completing a full history and exam, the physician should advise the young woman that her 20-year history of smoking and family history of lung cancer places her at substantial risk for smoking-related diseases including chronic bronchitis, emphysema, heart disease, and lung cancer. The physician might add that young women are currently more likely to get lung cancer than men, not just because more young women are smoking, but also because they may be more susceptible to lung cancer. The physician could also use motivational interviewing techniques to encourage the patient to quit smoking and refer her to a smoking cessation program.
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Karen is a 2017-2018 NEJM Editorial Fellow, Clinical Professor at UC Berkeley-UCSF Joint Medical Program and UC Berkeley School of Public Health, researcher on children’s nutrition and oral health, and member of American Academy of Pediatrics.