Could 15 years be the new 10 for repeat colonoscopy?

Adults who have tested negative for colorectal cancer (CRC) on initial colonoscopy and have no family history of CRC may only need to undergo a repeat screening after 15 years, according to a new Swedish study.

“Fifteen years between a first negative colonoscopy and a second one might be just as safe and effective as the current 10-year recommendation,” said senior study author Dr Mahdi Fallah from the German Cancer Research Center in Heidelberg, Germany. “This could save people from unnecessary procedures and free up resources for important colon cancer screening programmes.”

Most CRC screening guidelines recommend colonoscopy every 10 years for average-risk individuals. However, whether this 10-year interval could be safely expanded and for how long remains a debate.

Using the Swedish national registry datasets, Fallah and his team examined CRC diagnoses and CRC-related deaths among individuals without a family history of CRC. The study involved 110,074 adults (exposed group) who had their first colonoscopy at age 45 to 69 years and tested negative for CRC. Additionally, they did not have inflammatory bowel disease, a known risk factor for CRC.

Outcomes were compared with 1,981,332 individuals (controls) matched for sex, birth year, and baseline age, who either did not receive a colonoscopy or were screened and found positive for CRC. Up to 18 controls were matched with each exposed individual.  [JAMA Oncol 2024;doi:10.1001/jamaoncol.2024.0827]

The median age across groups was 59 years, and 59.2 percent were female. Baseline characteristics were similar between groups.

CRC incidence & mortality outcomes

From 1990 to 2018, there were 484 incident cases of CRC and 112 deaths from CRC in the exposed group and 21,778 and 5,521 cases, respectively, in the control group.

The group that received negative first colonoscopies had a “significantly lower” risk of both developing CRC and dying from it over the next 10 years. The 10-year standardized incidence ratio was 0.72, and the 10-year standardized mortality ratio was 0.55.

“In other words, the 10-year cumulative risk of CRC at year 15 in the exposed group was 72 percent that of the 10-year cumulative risk of CRC in the control group,’’ he explained.

“If we waited 15 years instead of 10 years for a second colonoscopy in this population, we might only miss catching two extra cases of CRC and one colorectal cancer death out of 1,000 people. But it would save a lot of unnecessary colonoscopies — about one per person,” said Fallah.

This means the recommended 10-year interval between colonoscopy screenings for adults with a negative first colonoscopy and no family history of CRC could be extended to 15 years, he added.

While the findings add to a body of evidence supporting the extension of the 10-year screening interval for those without abnormal findings, other experts cautioned that these may not be generalizable to more diverse populations, including Asia, where wide CRC screening has begun more recently.

“Validation of these results in other settings is critical to generalize these findings globally,” commented Drs Rashid Lui from The Chinese University of Hong Kong, Hong Kong, China, and Andrew Chan from Massachusetts General Hospital and Harvard University in Boston, Massachusetts, US, in a separate editorial. “Not only is it possible that the timing of the adenoma-carcinoma sequence may differ in non-European populations, but variation in the background incidence of CRC will significantly impact the number of incident CRCs prevented with a given screening interval.” [JAMA Oncol 2024;doi:10.1001/jamaoncol.2024.0249]