Screening for colorectal cancer should start at the age 50, according to the U.S. Preventative Services Task Force, an independent panel of experts in primary care and prevention that develops recommendations for clinical preventative services. About 90 percent of new cases of colorectal cancer occur in people 50 or older, according to the Centers for Disease Control and Prevention. However, the American Cancer Society began recommending screenings at age 45 for those at average risk in 2018 because of an increasing number of cases of colorectal cancer in younger adults.