Can Colonoscopy Interval be Safely Extended from 10 to 15 Years for Individuals at Average CRC Risk?
New research suggests the interval "could potentially be extended" without significant harms and could reduce unnecessary invasive procedures. , ie, missed early detection and CRC-specific mortality.
Among adults with no family history of colorectal cancer (CRC) and negative results on a first screening colonoscopy, there is “potential” to extend the screening interval for a second screening from 10 years to 15 years, according to interpretation of new study findings.1
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The 10-year interval is recommended by clinical guidelines in widespread use, Qunfeng Liang, MSc, a PhD student at the German Cancer Research Center and Heidelberg University, and colleagues wrote in JAMA Oncology.1 Those include statements from the American Cancer Society, American College of Physicians, and the US Preventive Services Task Force.2 Liang et al point to only limited evidence to support the 10-year period, however, and describe debate over whether the interval could be safely expanded.1
To investigate further, the research team conducted a matched cohort study using the nationwide Swedish family cancer data sets to create a sample of 110 074 individuals aged 45 to 69 years with negative findings on an initial screening colonoscopy between 1990 and 2016. They matched this cohort for sex, birthyear and baseline age with 1 981 332 controls. Control group participants either did not have a colonoscopy in the follow-up period or had positive findings followed by a CRC diagnosis. Median age in both groups was 59 years and women comprised approximately 60% of each.1
FINDINGS1
During up to 29 years of follow-up (1990-2018) Liang et al reported 484 incident CRCs and 112 CRC-specific deaths among study participants with negative findings on first colonoscopy. In the control group, there were 21 778 CRC cases and 5521 CRC-specific deaths, according to the results. Data were available for those with long-term follow-up (10 years or more) for 26% of the exposed group and for 28% from the control group.
The researchers found that at 15 years following a negative initial colonoscopy, the 10-year standardized incidence ratio was 0.72 (95% CI, 0.54-0.94) and the 10-year standard mortality ratio was 0.55 (95% CI, 0.29-0.94). Expressed in terms of risk, the 10-year cumulative risk of CRC at year 15 in the exposure group was 72% that of the 10-year risk in the control group and risk of CRC-specific death in the former was 55% that of the latter.
According to the study authors, their findings suggest that increasing the colonoscopy screening interval from 10 to 15 years for individuals with negative results on a first colonoscopy could miss the early detection of just 2 more cases of CRC per 1000 individuals and prevent 1 additional CRC-specific death per 1000 individuals. Extending the interval by 5 years could also potentially avoid 1000 “unnecessary invasive examinations,” researchers wrote.
When they conducted a sensitivity analysis including colonoscopies performed between 1990 and 2000 only, the team found the period of “significantly lower risk” was extended, but only nominally, to 16 years. When the analysis was adjusted for additional CRC risk factors including obesity, chronic obstructive pulmonary disease, alcohol use disorder and diabetes, results were consistent, ie, 16 years for CRC and 15 years for CRC-specific death, respectively.
Liang et al also investigated the effects of longer screening intervals on CRC incidence and associated mortality and found that with intervals of 16 to 20 years there was a gradual increase in additional CRC diagnoses per 1000 individuals from 4.5 at year 16 to 11.9 at year 20. Additional CRC-specific deaths increased from 2.0 to 3.6, respectively, at 16 and 20 years.
Previous research, the team observed, was only able to provide an estimated minimum interval between screenings. “The current study has the longest follow-up time, and to our knowledge, this is the first study to observe a point at which the reduced risk of CRC in the exposed group reached the level of CRC risk in the control group," the authors wrote. "Together with identifying harms of a longer interval, this finding allowed us to determine an optimal time for a second colonoscopy based on a large and long-lasting dataset."
In a discussion of their study’s limitations, the authors note the homogeneity of the study population and the inability to control for the quality of colonoscopy procedures and comorbidities, issues that also limit the ability to generalize findings to other populations.
“The findings of this cohort study suggest that for people without a family history of CRC and a first colonoscopy with findings negative for CRC, the recommended 10-year interval between colonoscopy screenings could potentially be extended to 15 years,” Liang and colleagues concluded, noting, again, that many unnecessary colonoscopies could be avoided.
