Colon cancer is striking younger American adults with greater frequency, and more tumors are being detected in advanced stages, worrying shifts in the occurrence of the potentially lethal disease that are sparking calls for wider screening and prevention measures.

About 20% of people with colon cancer in 2019 were under the age of 55, almost double the rate seen in 1995, according to a report from the American Cancer Society. Three out of five of Americans found to have colon cancer in 2019 were in the advanced stages of the disease, up from just over half in the mid 2000s, according to the report.

“It’s alarming to see how rapidly the whole patient population is shifting younger,” Rebecca Siegel, the group’s senior scientific director of surveillance…