(NewsNation) — Women are being diagnosed with lung cancer at much higher rates than men across all age groups, according to research by the American Cancer Society (ACS). 

“These findings are very concerning. 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.” said Dr. Ahmedin Jemal, lead author of the paper. 

Jemal said that cigarette smoking, the primary risk factor for lung cancer in the United States, shows no significant difference in prevalence between the two groups. 

The study revealed that the decline in lung cancer incidence rates between 2000-2004 and 2015-2019 was more significant in men than women, leading to higher incidence rates in women aged 35-54.  

For individuals aged 50-54, the rate per 100,000 person-years decreased by 44% in men compared to 20% in women. Consequently, the female-to-male incidence rate ratio increased from 0.73 during 2000-2004 to 1.05 during 2015-2019. 

However, among individuals aged 55 years or older, incidence rates remained lower in women, although the differences became increasingly smaller. For those aged 70 to 74 years, the female-to-male incidence rate ratio increased from 0.62 during 2000-2004 to 0.81 during 2015-2019. 

 “Lung cancer is still the leading cause of cancer death in the U.S., with 80% of cases and deaths caused by cigarette smoking. Further research is needed to understand the reasons behind the higher lung cancer incidence in younger and middle-aged women,” Jemal said. 

The Centers for Disease Control and Prevention (CDC) approximates that approximately 197,000 individuals receive a diagnosis of the disease annually across the nation.