Lung cancer, long the leading cause of cancer deaths among men in developed nations, is now also the top cause of cancer deaths in developed countries among women, according to a new report.

The findings reflect changing patterns in smoking among women worldwide, HealthDay reports. Many women began smoking in the 1970s, and the results are just now being seen in developed nations. Lead researcher Lindsey Torre of the American Cancer Society notes, “It takes about two to three decades to see lung cancer deaths due to smoking, because lung cancer does take a long time to develop.”

Lung cancer has been the top cause of cancer deaths among U.S. women for a number of years, the article notes. “In many developed countries breast cancer death rates have been stable or decreasing for the past couple of decades, which is due to early detection and improved treatments,” Torre said.

While lung cancer death rates worldwide have continued to rise, the rate has leveled off in the United States, she added. Torre predicted that as smoking rates among women decrease, lung cancer rates in developed nations will also drop over the next three decades.

In developing countries, lung cancer rates and deaths are predicted to rise as more men and women start to smoke, she said.

The findings appear in CA: A Cancer Journal for Clinicians.