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A new study found that women ages 35 to 54 are experiencing higher rates of new lung cancer cases than men in that age group.
Experts aren’t quite sure why this is the case, as cigarette smoking—the leading risk factor for lung cancer—is not more prevalent in women.
Lung cancer screening is only recommended for adults over 50 who have smoked, but all people should make sure they’re avoiding radon, secondhand smoke, and other lung cancer risk factors.
Lung cancer—historically associated with men and those who smoke—is now being diagnosed more often in younger and middle-aged women, new research suggests.
The study, published last week in JAMA Oncology, found that the rates of newly diagnosed lung cancer cases were higher in women ages 35 to 54 than in men of the same age—that’s despite an overall downward trend of lung cancer incidence rates.
“These findings are very concerning,” lead study author Ahmedin Jemal, DVM, PhD, senior vice president for surveillance and health equity science at the American Cancer Society, said in a news release.
“We don’t know why lung cancer incidence rates among younger and middle-aged individuals are now higher in women than men, reversing the historical pattern,” Jemal continued. “Cigarette smoking prevalence, the major risk factor for lung cancer in the United States, is not higher in younger women than younger men, as are other established risk factors such as occupational exposures.”
Lung cancer is the second most common cancer for both men and women and in 2023, the American Cancer Society estimates that 117,550 men and 120,790 women will be diagnosed with a new case of lung cancer.
Here’s what experts had to say about how the review changes our understanding of lung cancer, and what younger and middle-aged women should know about the disease.
Lung Cancer in Younger and Middle-Aged Women
The new study expands on previous research from the American Cancer Society, published in 2018, which found higher lung cancer incidence in women under 50 years old, compared to men of the same age.
To widen the scope of that research, scientists also paid special attention to cancer incidence rates in women ages 50 to 54. And while the original research looked at data between 1995 and 2014, the new study analyzed data from 2000 to 2019.
That data—from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) program—revealed that, while lung cancer incidence rates declined for almost all age groups and sexes over the span of two decades, men saw a greater decline in rates than women—this resulted in a higher lung cancer incidence among women ages 35 to 54.
Looking closer, among people ages 50 to 54, the lung cancer incidence rate per 100,000 person-years decreased by 44% for men, while it only decreased by 20% for women. (Person-years are based on the number of people in the study and how long the study goes on for.)
For those over age 55, lung cancer is still more prevalent in men than in women. However, that gender gap narrowed over two decades.
Related: Study Claims Cancer Screenings Don’t Save Lives—Here’s What to Know About the New Research
What We Know (and Don’t Know) About Lung Cancer Disparities
The research broaches “a lot of continued unanswered questions” regarding the ways that gender, age, and lung cancer intersect, said Elaine Shum, MD, assistant professor at the Perlmutter Cancer Center at the NYU Grossman School of Medicine.
“We don’t know why lung cancer incidence rates are higher in young women than young men,” Jemal told Health in a statement. “Smoking prevalence, which causes about 80% of lung cancer in the U.S., is not higher in young women than young men.”
There is a slightly higher smoking prevalence specifically among women born in the 1960s as compared to men, the study found, but in general, men still smoke more than women.
The fact that younger women are seeing more lung cancer cases could be linked to other risk factors besides smoking, Shum explained.
Some research has suggested that women may be more susceptible to air pollution, which has been linked to lung cancer, Shum said. Radon—a naturally-occurring gas—can cause lung cancer, as can secondhand smoke, she said. It’s possible that those are driving gender differences in some way.
Mutations developed over the course of someone’s life may also play a role, Shum added.
“In general, people with lung cancer who have never smoked cigarettes before tend to have higher incidence of having mutations associated with their lung cancer,” she said. “Again, we don’t know exactly the reasons for that.”
For now, there are a number of theories as to why women’s lung cancer rates don’t seem to be diminishing as quickly as men’s, even though they’re not smoking more.
Getting to the bottom of this “is an active area of research,” Jemal added.
Related: How To Prevent Lung Cancer
Lung Cancer Prevention and Screening
As researchers uncover gender differences in lung cancer incidence, more work will also need to be done to address those disparities.
People should talk to their physicians if they have a family history of lung cancer, Shum advised. And people should avoid cigarette smoke and secondhand smoke, get their homes tested for radon, and follow health guidelines at work so they don’t accidentally expose themselves to carcinogens.
Beyond this, however, there aren’t a ton of warning signs to look out for, and the disease seems to present similarly in both men and women, Shum said.
Symptoms may include coughing, chest pain, tiredness, weight loss, or shortness of breath—they could be confused for another illness, and may not even manifest until later stages of the cancer.
“This is why screening is such an important part of lung cancer,” said Shum. “Even someone with stage four lung cancer might only present as having a cough.”
Currently, the U.S. Preventive Services Task Force recommends lung cancer screening for adults aged 50 to 80 who have a 20 pack-year smoking history and currently smoke, or have quit within the past 15 years.
“For people who have never smoked cigarettes before, there actually are no set guidelines for [screening],” explained Shum.
Research that finds differences in lung cancer incidence based on a person’s age, gender, ethnic background, or other factors could one day be used to expand these guidelines.
Currently, Shum is running a study for Asian women who are non-smokers and is screening them for lung cancer starting at age 40. This ethnic group tends to have higher incidences of lung cancer that are associated with mutations, she explained.
“It’s definitely an unmet need,” said Shum. “It’s clear that we need to identify additional high-risk populations for developing lung cancer, and see what kind of screening guidelines and initiatives we might want to try to implement for those populations.”
But for now, this review is a reminder—both to healthcare professionals and to younger and middle-aged women—that there’s a real lung cancer risk for this population.
“Anybody with lungs could get lung cancer,” Shum said. “We just need to recognize that there are population differences as well.”
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