The incidence of colorectal cancer (CRC) in people 50 years or older has declined; however, the incidence among people age 20 to 49 years has increased, according to a report published by JAMA Surgery (2014; doi:10.1001/jamasurg.2014.1756).

CRC is the third most common cancer among men and women, with an estimated 142,820 new cases and an estimated 50,830 deaths in the United States in 2013. From 1998 through 2006, the incidence of CRC declined 3% per year in men and 2.4% in women, a decrease largely attributed to an increase in screening, which is recommended for all adults older than 50 years.

However, the incidence of CRC in adults younger than 50 years, for whom screening is not recommended, appears to be increasing; and those patients are more likely to present with advanced disease, according to background information in the study.

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Researcher Christina E. Bailey, MD, MSCI, of the University of Texas MD Anderson Cancer Center in Houston, and her co-authors analyzed age disparities in trends in CRC incidence in the United States. The authors used data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) CRC registry for all patients with colon or rectal cancer diagnosed from 1975 through 2010 (N=393,241).

The study results indicate that overall, the CRC incidence rate declined 0.92% between 1975 and 2010; CRC incidence rates declined by 1.03% in men and 0.91% in women. The most pronounced decline was 1.15% in patients 75 years or older, while the rate for patients age 50 to 74 years dropped 0.97%. However the CRC incidence rates increased among patients age 20 to 49 years, with the biggest increase (1.99%) seen among patients age 20 to 34 years. The rate increased 0.41% among patients age 35 to 49 years.

The authors estimate that by 2020 and 2030, the incidence rate of colon cancer will increase by 37.8% and 90%, respectively, for patients 20 to 34 years old, while decreasing by 23.2% and 41.1%, respectively, for patients older than 50 years.

By 2020 and 2030, the incidence rates for rectosigmoid and rectal cancers are expected to increase by 49.7% and 124.2%, respectively, for patients 20 to 34 years old, while decreasing 23.2% and 41%, respectively, for patients older than 50 years, according to the results.

“The increasing incidence of CRC among young adults is concerning and highlights the need to investigate potential causes and external influences such as lack of screening and behavioral factors,” the authors concluded.

In a related commentary (doi:10.1001/jamasurg.2014.1765), Kiran K. Turaga, MD, MPH, of the Medical College of Wisconsin, Milwaukee, wrote: “In the setting of these congratulatory reports of a successful public health screening program, this report from Bailey [and colleagues] is rather unsettling.”

“This report should stimulate opportunities for development of better risk-prediction tools that might help us identify these individuals early and initiate better screening/prevention strategies. The use of stool DNA, genomic profiling, and mathematical modeling might all be tools in the armamentarium of the oncologist in the near future,” the author concluded.