A 1- or 2-year delay in recommended colorectal cancer (CRC) screenings had little effect on most people’s risk of illness or death from cancer, provided they eventually got screened, according to a modeling study of the impact of pandemic-related screening delays.
Most patients whose screening was delayed still benefited through a reduction in risk of cancer or death, but that benefit was lower than it would have been had they been screened on time, particularly for 65-year-olds who hadn’t ever been screened for CRC.
Extending the upper ages for undergoing screening or substituting fecal immunochemical testing (FIT) for colonoscopies blunted some of this negative effect for 50-year-olds who had never been screened and for previously screened 60-year-olds, but those mitigation strategies weren’t as helpful for never-screened 65-year-olds, report Soham Sinha, MS, of Weill Cornell Medicine, and his colleagues.
Because older patients lose the most benefit from delayed CRC screenings, Sinha and his colleagues suggest, they should be prioritized when access is reduced.
The findings were published online in Gastroenterology.
Modeling the Impact of Missed Screenings
CRC screenings dropped by as much as 82% at the start of the pandemic, Sinha and his co-authors note, and screening rates haven’t yet recovered as new COVID variants arise.
The researchers therefore sought to evaluate the potential clinical impact of screenings that were missed because of the pandemic on three groups of people who were at average risk of CRC: people who were 50 years old and had never been screened, people who were 65 and had never been screened, and people who had been screened by age 50 but were due for a colonoscopy screening at age 60.
They modeled the incidence and mortality of colorectal cancer for a 1-year and a 2-year delay in screening compared to on-time screening with a colonoscopy or an annual FIT through age 75, or colonoscopy surveillance through age 80.
Among never-screened 50-year-olds, waiting a year or two to start colonoscopy screening resulted in a 69% reduction in colorectal cancer incidence instead of the 70% reduction that would have occurred with on-time screening. Similarly, the reduction in risk of death from delayed screening was 75% instead of 76% with on-time screening.
A 1- or 2-year delay in starting FIT screening in this group led to a reduction in the benefit of lower risk by one percentage point: patients had a 57% lower risk of cancer from a 1-year screening delay and a 56% reduction in risk from a 2-year delay, compared to a 58% reduction in risk without any delays. In terms of mortality, benefit fell by one absolute percentage point for each year of delay.
Restoring the Benefits of Screening
The most effective way to mitigate each of those lost percentage points from colonoscopy delays was to combine two rescue strategies: using FIT screening instead of colonoscopy when colonoscopy access was reduced, and extending the upper ages of colonoscopy screening to age 76–77 and colonoscopy surveillance to age 81–82.
Solely extending the ages for undergoing screening and surveillance was more effective than solely substituting FIT screening for colonoscopies. To offset the impact of an FIT delay, extending the upper age of the screening or surveillance period was effective.
The negative effect of delayed colonoscopy screenings was greater for never-screened 65-year-olds, whose reduction in risk of developing CRC fell to 53% to 54%, rather than the 66% reduction in risk they would have had with on-time screening. The reduction in risk of mortality from CRC was 60% instead of 74% if screenings were delayed instead of occurring on time.
“Starting at age 65 afforded individuals two lifetime colonoscopies, as opposed to one at age 66 or later, given that colorectal screening ended at age 75,” the authors write. “Rescue strategies decreased but did not negate the impact of pandemic-related colorectal screening delays.”
For never-screened 65-year-olds who experienced delays in FIT, undergoing screening 1 year late equated to a 41% reduction in cancer risk, and undergoing screening 2 years late resulted in a 38% reduction, compared to a 44% reduction with on-time FIT screening. The reduction in mortality fell from 60% with on-time screening to 57% with a 1-year delay and 54% with a 2-year delay. Though extending the upper age limited reduced this negative effect, it did not eliminate it.
The researchers found that delaying screening by 1 or 2 years among 60-year-olds who had had a colonoscopy at age 50 only modestly reduced the benefit of reduced risk of CRC or death.
“Rescue strategies mitigated or negated impact from colorectal screening delays and included FIT-based screening when colonoscopy was unavailable, with or without extended screening through ages 75 or 76,” the authors report.
One limitation of the study was its lack of cost-effectiveness calculations, which made it impossible to evaluate the economic implications of either the delays in screening or the proposed mitigation strategies.
“Our work suggests that among the 20% of the US population aged 50–75 who are unscreened for colorectal cancer, older adults would experience the most clinical benefit from colorectal cancer screening if resources were limited during the COVID-19 pandemic,” the authors write.
Younger people who hadn’t yet been screened and those who had been screened at least once with a colonoscopy would not experience as dramatic a reduction in benefit once they underwent screening, they conclude.
One author was supported by the National Cancer Institute. One author has advised Universal Dx and Lean Medical and has consulted for Clinical Genomics, Medtronic, Guardant Health, and Freenome. No other relevant financial relationships have been disclosed.
Gastroenterology. Published online August 22, 2022. Full text
Tara Haelle is a Dallas-based health and science journalist. Follow her at @tarahaelle.
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