BACKGROUND AND PURPOSE: 

• Lung cancer is the leading cause of preventable cancer deaths in the US  
  • Smoking accounts for 80% of lung cancer deaths  
• Lung cancer rates between men and women have converged and recent data suggests higher incidence rates in young women vs young men  
• Jemal et al. (N Engl J Med, 2018) sought to determine whether the higher rates of lung cancer in young women compared to young men were maintained in contemporary birth cohorts and whether these differences could be explained by sex differences in smoking behaviors

METHODS: 

• Nationwide population-based incidence of lung cancer according to sex, race or ethnic group, age group, year of birth, and calendar period of diagnosis (1995-2014) 
• Data extracted from North American Association of Central Cancer Registries (NAACCR) 
• Female-to-male incidence rate ratios were calculated  
• The prevalence of cigarette smoking was also measured using the National Health Interviews Survey

RESULTS: 

• Incidence of lung cancer has generally decreased among individuals age 30 to 54 years all races and ethnic groups 
  • Steeper decline seen in men  
• Among non-hispanic whites, the female to male incidence rate ratios have therefore increased  
  • 1995-1999: Ratio 0.88 (95% CI, 0.84 to 0.92)  
  • 2010-2014: Ratio 1.17(95% CI, 1.11 to 1.23)  
• Ratio crossed 1.0 the age groups of 30 to 34, 35 to 39, 40 to 44, and 45 to 49 years 
• Among other races/ethnicities, this crossover phenomenon occurred only among Hispanic women 
  • 1995-1999: Ratio 0.79 (95% CI, 0.67 to 0.92) 
  • 2010-2014: Ratio 1.22 (95% CI, 1.04 to 1.44) 
• Change in sex-specific ratio (from lower to higher incidence) is specific to the birth cohort born since the mid-1960’s 
• The prevalence of smoking in women have approached but not surpassed smoking rates in men since 1965 
• Use of tobacco products other than cigarettes (e.g., cigars) remains much lower among women, compared to men

CONCLUSION: 

• The incidence of lung cancer is now higher in younger white and Hispanic women compared to their male counterparts, but this change cannot entirely be explained by smoking behaviors   
• Among Hispanic women, smoking prevalence is substantially lower in women compared to men  
• Evidence that women are more susceptible to lung cancer is inconclusive  
• Since 15% of lung cancer in women and 10% in men is unrelated to smoking, other exposures may be related to the results seen in this study (e.g., men may no longer be exposed to levels of asbestos and arsenic in the workplace)  
• While more studies are needed, authors state in the their conclusion that their results  

…may foreshadow a higher future burden of overall lung cancer among women than among men as younger cohorts age, which further underscores the need to intensify antitobacco measures to decrease smoking among young women”

Learn More – Primary Sources: 

Higher Lung Cancer Incidence in Young Women Than Young Men in the United States

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