More young and middle-aged women are being diagnosed with lung cancer at a higher rate than men, and scientists are struggling to understand why, new research shows. Awareness of the disease’s effects on women is lacking, experts say, and the US government spends significantly less on its research than on similar studies in men.

“When you ask people what the number one cancer killer of women is, most will say that it’s breast cancer. It’s not. It’s lung cancer. Lung cancer is a women’s health disease, but we clearly need to educate more people about it,” said Dr. Andrea McKee, a radiation oncologist and volunteer medical spokesperson for the American Lung Association.