July 22 (UPI) -- Colorectal cancer cases have risen sharply among young people since 1970, new research shows.
The percentage of people under age 50 rose to 12.2 percent in 2015, up from 10 percent in 2004, according to a study published Monday in Cancer.
"Several studies have shown that the rates of colorectal cancer in younger adults have risen slowly in the U.S. since the 1970s, but for practicing physicians, it feels like we are seeing more and more young people with colorectal cancer now than we were even 10 years ago," Boone Goodgame, a researcher University of Texas at Austin and study author, said in a news release. "Until just last year, guidelines recommended colon cancer screening beginning at 50. Now many guidelines do recommend screening at age 45, but most physicians and patients don't appear to be following those recommendations."
The researchers used data from the National Cancer Database registry on patients who were diagnosed with colorectal cancer between 2004 and 2015.
From the database, which containes more than 70 percent of new cancer diagnoses in the U.S., researchers analyzed data on more than 130,000 people were under age 50 and 1 million people over age 50.
Younger adults accounted for 51.6 percent stage III and stage IV cancer cases compared to 40 percent in the older group.
Among colorectal cancer diagnoses, black and Hispanic people have disproportionately higher rates than white people. Young adults in the highest income bracket also had the highest percentage of diagnoses -- and the rates continued to climb over time across all income levels.
Another study showed colorectal cancer cancers among people younger than 50 were particularly high in western states.
Adults should get regular colonoscopies or other screenings for colorectal cancers starting at age 45, according to the American Cancer Society.
"Because the number of colorectal cancer cases from inherited causes are much higher in younger individuals, it is unknown whether screening for sporadic cases in a group with such low disease rate can result in a favorable balance of harms and benefits," Goodgame said.