More Adults Aged 40-59 Have Polyps Greater Than 9 mm on Colonoscopy

By Lisa and Rapaport

January 15, 2021

(Reuters Health) - The proportion of adults 40 to 59 years old who have polyps larger than 9mm on colonoscopy has increased in recent years, a U.S. study suggests.

Researchers examined data from the Clinical Outcomes Research Initiative on 87,745 patients aged 40 to 49 years old and 310,905 patients aged 50 to 59 years old who underwent a colonoscopy between 2002 and 2014.

While the prevalence of polyps larger than 9mm declined from 2002 to 2005, the prevalence increased from 2005 to 2014 for all age groups in the study. The increase in prevalence of polyps larger than 9mm increased for those aged 40 to 44 (39%), 45 to 49 (44%), 50 to 54 (54%), and 55 to 59 (53%), according to the report in Gastroenterology.

"We have seen an increase in rates of colorectal cancer (CRC) before age 50, so it follows that there could also be an increase in rate of cancer precursor lesions such as polyps greater than 9mm," said senior study author Dr. David Lieberman, chief of the Division of Gastroenterology and Hepatology at Oregon Health and Science University in Portland.

"Our study is one of the first to demonstrate that cancer precursor rates have also changed over time in younger individuals," Dr. Lieberman said by email.

The study included patients who had a family history of colorectal cancer, needed polyp or colorectal cancer surveillance, had average risk for these tumors, or required a diagnostic evaluation.

In 2005, the prevalence of polyps greater than 9mm was lowest among those 40 to 44 (3.9%) and increased with age, reaching the highest proportion among patients 55 to 59 (6.4%).

By 2014, the prevalence was still lowest among those 40 to 44 (5.4%) and increased with age to reach the highest proportion among patients 55 to 59 (9.8%).

The results underscore the importance of clinical practice recommendations from the American Cancer Society and the United States Preventive Services Task Force that providers consider colorectal cancer screening starting at age 45, the study team writes.

One limitation of the study is that the data don't fully explain why a growing number of people in the U.S. are developing early onset colorectal cancer, the researchers point out.

"Likely some of the increase is due to more colonoscopies being done - thus, some slow-growing cancers that previously might have been diagnosed at age 50-51 are instead being diagnosed at ages 48-49," said Dr. Douglas Corley, a gastroenterologist and researcher at Kaiser Permanente Northern California, in Oakland.

"Yet it is also clear that, even accounting for greater use of colonoscopy in recent years, that the incidence of younger-onset cancer is truly increasing," Dr. Corley, who wasn't involved in the study, said by email.

It's possible that environmental factors or personal risk factors for colon polyps such as obesity or a diets low in fruits and vegetables might play a role in the rising prevalence of early-onset colorectal cancer, Dr. Corley added. More research is needed to better understand this trend, he said.

The study results do, however, reinforce the critical need for initiating screening at age 45, said Dr. Andrew Wolf of the University of Virginia School of Medicine in Charlottesville.

"If folks are reluctant to have a colonoscopy, stool-based screening is easy, can be done at home without any preparation, and can, like colonoscopy, definitely reduce the risk of dying needlessly from colorectal cancer," Dr. Wolf, who wasn't involved in the study, said by email.

"I am particularly concerned that during the pandemic, folks are putting off preventive care like colorectal cancer screening," Dr. Wolf added. "For those who have, it's time to get back on the bandwagon and get screened with whichever test they feel comfortable."

SOURCE: Gastroenterology, online January 5, 2021.