Researchers saw a sharp increase among teenagers but noted that the overall number of cases in that age group are very low.

Colorectal cancer rates have been rising for decades among people too young for routine screening, new research finds.

Routine screening is recommended every 10 years starting at age 45; the new study focused on rates of the disease in children and adults ages 10 to 44, using data from the Centers for Disease Control and Prevention.

Cases of colorectal cancer were on the rise in all age groups, the researchers found.

“It means that there is a trend,” said Dr. Islam Mohamed, an internal medicine resident physician at the University of Missouri-Kansas City who led the research. “We don’t know what to make of it yet, it could be lifestyle factors or genetics, but there is a trend.”