Rates of certain types of cancer on the rise for younger people in the U.S.

FOX's Lisa Lacerra reports: 

People born in the 1990's about twice as likely to be diagnosed with colon cancer as people born in the middle of the last century. That's according to researchers from the American Cancer Society. The trend worse for rectal cancers, showing that younger people were about four times as likely to be diagnosed with those cancers than older adults.

Better screening has helped lower colon and rectal cancer for older Americans, but for those under 50, routine screening is not recommended.

The study didn't explore why cancer rates are rising among younger adults, but the study's leader saying it may be linked with changes in physical activity levels and diet.

Lisa Lacerra, FOX News.