“We’ve seen a huge increase in the number of DCIS cases diagnosed in the last 20 years,” says Julia White, MD, director of breast radiation oncology at the Ohio State University Comprehensive Cancer Center.
In the 1990s, only about 15,000 to 18,000 DCIS cases were diagnosed per year, she says; now, that number has grown to more than 60,000, according to the American Cancer Society. “That’s because so many women are now getting mammograms, and the technology is so good, that we pick up very small lesions,” says Dr. White.
The good news? Women are getting treated earlier than ever, which means there are fewer chances for DCIS to break out of the milk duct and become invasive. (This happens in anywhere from 20% to 50% of untreated DCIS lesions, according to the ACS.) The bad news? There’s no way to tell which lesions will become invasive, so some experts say there’s a real danger of overdiagnosis and unnecessary treatment.