Dr. Richard C. Wender, chief cancer control officer at the American Cancer Society, said the growing use of colonoscopy was credited with the drop in cancer incidence. Colonoscopy use nearly tripled among adults ages 50 to 75, from 19 percent in 2000 to 55 percent in 2010, Wender said.
Lead author Rebecca Siegel, an epidemiologist at the American Cancer Society, said the research team used data from the National Cancer Institute's Surveillance, Epidemiology and End Results program and the Centers for Disease Control and Prevention's National Program of Cancer Registries.
The researchers found from 2001 to 2010, overall colorectal cancer incidence rates decreased by an average of 3.4 percent per year. However, trends varied substantially by age.
The rate of decline surged for those age 65 and older, with the decline accelerating from 3.6 percent per year during 2001 to 2008 to 7.2 percent per year from 2008 to 2010.
"The larger declines among Medicare-eligible seniors likely reflect higher rates of screening because of universal insurance coverage," the authors wrote in the study. "In 2010, 55 percent of adults ages 50 to 64 reported undergoing a recent colorectal cancer screening test, compared with 64 percent of those age 65 and older."
Cancer incidence rates declined by 3.9 percent per year among adults age 50 and older, but increased by 1.1 percent per year among men and women age 50 and younger.
The findings, Colorectal Cancer Statistics, were published in CA: A Cancer Journal for Clinicians.