Deferring a second colonoscopy for five years has been called safe in cancer screening

Currently, it is recommended that all people over the age of 45 without a family history of colorectal cancer should undergo a colonoscopy every 10 years to screen for colorectal cancer. German and Swedish scientists conducted a retrospective population-based cohort study and concluded that if the first colonoscopy is negative, this interval can be safely extended to 15 years. The publication appeared in the journal JAMA Oncology. Mahdi Fallah from the German Cancer Research Center (DKFZ) and colleagues from Germany and the US analyzed data from Swedish national health registries from 1990-2018. The main group included all 110074 people with an unremarkable family history who underwent a negative screening colonoscopy at ages 45-69 years, while the control group included 1981332 of their peers, similar in all other respects, who did not undergo the study.

The risk of colorectal cancer and death in the 15-year period after colonoscopy was significantly lower in the main group compared with the control group at the corresponding age. Fifteen years after the first colonoscopy, which showed no polyps, adenomas, carcinomas in situ, or colorectal cancer, the 10-year standardized ratio of new cases in the main group was 0.72 (95 percent confidence interval, 0.54-0.94) and death from the disease was 0.55 (95 percent confidence interval, 0.29-0.94). That is, the cumulative 10-year risk by year 15 was 72 percent of that in the control group. Increasing the interval between studies from 10 to 15 years would result in a lack of early detection of cancer in two people out of a thousand and prevent death from it in one out of a thousand, but would avoid a thousand unnecessary colonoscopies, the authors calculated.