Higher Rates of Lung Cancer in Young Women Unexplained

New research shows that lung cancer rates are increasing among young women in the United States and researchers aren’t sure why. In fact, a new study found rates of lung cancer are increasing specifically among white and Hispanic women, ages 30-54.1

What does the research show?

Over the past 20 years, the age-specific incidence of lung cancer has decreased among both men and women 30-54 years old in all races and ethnic groups. But, the declines among men have been steeper. In just one example, this study showed that rates of lung cancer among white women ages 40-44 went from 12% lower than men during 1995-1999 to 17% higher in 2010-2014.2

The increase seems to have occurred despite the fact that women tend to smoke fewer cigarettes than men. Smoking is known to be the cause of approximately 80% of the country’s 154,000 lung cancer deaths each year.

These findings recently appeared in the New England Journal of Medicine in a study funded by the American Cancer Society and the National Cancer Institute.1, 2

At greater risk: women born after 1965

Historically, women were less likely to smoke, began smoking at older ages, and smoked fewer cigarettes per day, which all contributed to their lower lung cancer rates compared to men. However, women’s smoking behaviors have become more similar to men’s over the past few decades, though women still tend to smoke fewer cigarettes per day.

This latest study looked at the rates of lung cancer and the prevalence of smoking by sex, race or ethnic group, age and year of diagnosis to calculate female-to-male incidence rates. Ages were grouped by 30-34, 35-39, 40-44, 45-49 and 50-54 years old. The year a person was diagnosed was segmented as 1995-1999, 2000–2004, 2005–2009, and 2010–2014.

The cause remains unexplained

The causes for the increase in lung cancer diagnosis puzzled researchers because the numbers cannot be explained by sex differences in smoking behaviors or environmental exposure, the most common reasons given for why men had lung cancer in higher rates than women in the past. In fact, this study found that more young Hispanic women were diagnosed with lung cancer despite being substantially less likely to smoke compared to Hispanic men.

The scientists explored several possible reasons for the increase in lung cancer among younger women, none of which explained the increase. These included:

  • The prevalence of cigarette smoking and smoking behaviors.
  • Differences in smoking cessation patterns between men and women.
  • Theories that women are more susceptible to the harmful effects of tobacco.
  • Exposure to lung carcinogens, such as asbestos and arsenic, second-hand smoke and air pollution.
  • Changes to the design and manufacture of cigarettes.
  • Differences in the frequency and age of detection of lung tumors in women and men.

Lung cancer data came from the North American Association of Central Cancer Registries (NAACCR) from 1995 to 2014 from 46 states and the District of Columbia. The National Health Interview Survey provided evidence about smoking behaviors and cigarette use from 1970 to 2016.

More research is needed

Scientists know that women seem to be more susceptible to developing lung cancer but less likely to die from it. This study points to some research that suggests genetic differences in women may make them more likely to develop adenocarcinoma and squamous-cell carcinoma, common types of the disease.

These findings are particularly troubling since lung cancer causes more preventable deaths than any other cancer in the U.S.

To combat the growing incidence of lung cancer in women, the study recommends more sex-specific research on the risks of lung cancer and smoking-related susceptibility to lung cancer to identify the reasons for the higher rates. They also recommend more intense anti-tobacco and anti-smoking communications directed specifically to younger women.

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