Colon cancer incidence rates have dropped 30% in the United States in the last 10 years among adults 50 years and older due to the widespread uptake of colonoscopy, with the largest decrease in people older than 65 years. Colonoscopy use has almost tripled among adults age 50 to 75 years, from 19% in 2000 to 55% in 2010.

The findings come from Colorectal Cancer Statistics, 2014, published in CA: A Cancer Journal for Clinicians (2014; doi:10.3322/caac.21220). The article and its companion report, Colorectal Cancer Facts & Figures, were released by American Cancer Society researchers as part of a new initiative by the National Colorectal Cancer Roundtable to increase screening rates to 80% by 2018.

Colorectal cancer is the third most common cancer and the third leading cause of cancer death in both men and women in the United States. Its slow growth from precancerous polyp to invasive cancer provides a rare opportunity to prevent cancer through the detection and removal of precancerous growths. Screening also allows early detection of cancer, when treatment is more successful. As a result, screening reduces colorectal cancer mortality both by decreasing the incidence of disease and by increasing the likelihood of survival.

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The researchers, led by Rebecca Siegel, MPH, used incidence data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) program and the Centers for Disease Control and Prevention’s National Program of Cancer Registries, as provided by the North American Association of Central Cancer Registries (NAACCR).

During the most recent decade of data (2001 to 2010), overall incidence rates decreased by an average of 3.4% per year. However, trends vary substantially by age. Rates declined by 3.9% per year among adults age 50 years and older but increased by 1.1% per year among men and women younger than 50 years. That increase was confined to tumors in the distal colon and rectum, patterns for which a rise in obesity and emergence of unfavorable dietary patterns has been implicated.

Most strikingly, the rate of decline has surged among those 65 years and older, with the decline accelerating from 3.6% per year from 2001 to 2008 to 7.2% 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 2010, 55% of adults age 50 to 64 years reported having undergone a recent colorectal cancer screening test, compared with 64% of those age 65 years and older.”

Like incidence, mortality rates have also declined most rapidly within the past decade. From 2001 to 2010, rates decreased by approximately 3% per year in both men and women, compared with declines of approximately 2% per year during the 1990s.

“These continuing drops in incidence and mortality show the lifesaving potential of colon cancer screening; a potential that an estimated 23 million Americans age 50 to 75 years are not benefiting from because they are not up to date on screening,” said Richard C. Wender, MD, American Cancer Society chief cancer control officer.