Colonoscopy screening reduces the incidence and mortality of colorectal cancer (CCR) by enabling detection and removal of precancerous lesions. However, the available evidence on the optimal screening interval is limited.
In 2019, a systematic review and meta-analysis on the topic showed that the detection of advanced malignancies within 10 years of a negative screening colonoscopy is a rare event (1).These results led the researchers to wonder whether in these cases the prevailing recommendation (in accordance with the guidelines) to repeat the colonoscopy after 10 years should be respected, or whether it was better to wait for a longer period of time (2).
Screening colonoscopy: data from the world’s largest registry
To understand if it was possible to extend the screening colonoscopy intervals beyond the recommended 10 years, the researchers analyzed data from the German screening colonoscopy registry, which is the largest registry in the world and includes the registration of about 10 million screening colonoscopies (2).
Primary screening colonoscopy for the prevention and early diagnosis of JRC has been offered in Germany since October 2002. The age eligible to start is 50 years for men and 55 years for women and if the first screening colonoscopy is performed before the age of 65, a second screening colonoscopy is proposed 10 years later.
47,949 men (39.9%) and 72,349 women (60.1%) were identified with a colonoscopy that could be reliably classified as 565,864 repeated screening colonoscopy and 688,264 screening colonoscopies in men and women aged> 65 years old.
In subjects with repeated screening colonoscopy the study showed the following data:
- hyperplastic polyps were found in 34,741 (28.9%) individuals.
- about half (58,978 [49.0%]) performed a second screening colonoscopy 10 years after the previous negative colonoscopy. Of the remainder, 34,762 (28.9%) rescreened after 11 years and 14,427 (12.0%) after 12 years, while only about 10% had a screening interval> 13 years.
- The prevalence of CCR and advanced colorectal malignancies (ADNs) was 75%-85% and 44%-60% lower than all screening colonoscopies 10 years after a negative colonoscopy.
- In subjects with longer intervals, the prevalence continued to be reduced in particular, at 11 and 16 years by 62-82% and 38-50%, respectively.
- The prevalence of DNA was higher (about 40%) in men than in women and regardless of the interval between examinations.
- The prevalence of DNA was very low (about 4%) in women aged <75 years, also for intervals up to 13 years and with a prevalence only slightly higher (4-6%) for intervals> 14 years.
Points of focus for clinical practice
Premise — it is not possible to extend the indications emerged from this study to all.Particular caution should be exercised in individuals with indication for a colonoscopy: to clarify the symptoms (eg rectal bleeding); with already defined intervals; or at higher risk of CCR (e.g. inflammatory bowel disease).
That said, the results of study (2) support the following points:
- After a negative screening colonoscopy it is rare to detect findings of advanced neoplasia within 10 years (1,2). A reassuring and consistent evidence with previous studies confirming that screening colonoscopy should not be repeated before 10 years, as currently recommended, but as frequently disregarded in clinical practice.
- Prevalence estimates for intervals greater than 10 years are very precise (2).
- The prevalence of DNA is still low even after more than 10 years from a negative colonoscopy (2).
- There are differences in sex and age in participants in repeated screening colonoscopy (2).
- It is known that male sex is associated with higher risks of ADN and CCR, as evidenced by the prevalence of ADN about 60% higher in men than in women in the control group (2).
- Differences between men and women, as well as the lower prevalence of younger versus older subjects among repeat screening participants, indicate the potential use of risk stratification by sex and age for define screening colonoscopy intervals (2).
- caution should be exercised in generalizing from these results, because they focus specifically on asymptomatic individuals at average risk of CCR with negative screening colonoscopy who chose to repeat it after a period> 10 years.
- For asymptomatic patients with a negative baseline examination, currently recommended screening colonoscopy intervals are safe and suggest that gender and age could drive the potential risk-adjusted extension of screening intervals beyond 10 years, particularly in female and younger subjects.
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