Expected long-term impact of the German screening colonoscopy programme on colorectal cancer prevention: analyses based on 4,407,971 screening colonoscopies.

Aim: Endoscopy based screening programmes for colorectal cancer (CRC) are being implemented in an increasing number of countries. In Germany, screening colonoscopy at age 55 or older has been offered since the end of 2002. We aimed to estimate the long-term impact of this offer on CRC prevention.

Methods: We estimated numbers of prevented CRC cases by expected age and year of their (prevented) occurrence over four decades (2005-2045) by four state Markov models (non-advanced adenoma, advanced adenoma, preclinical CRC, clinically manifest CRC). Estimates are based on screening colonoscopies reported to the German screening colonoscopy registry in 2003-2012 (N=4,407,971), transition rates between the four states and general population mortality rates.

Results: Numbers of prevented clinically manifest CRC cases are projected to increase from <100 in 2005 to approximately 6500 in 2015, 12,600 in 2025, 15,400 in 2035 and 16,000 in 2045, compared to approximately 58,000 incident cases observed in 2003. The annual number of prevented cases is expected to be higher among men than among women and to strongly vary by age. The vast majority of prevented cases would have occurred at age 75 or older.

Conclusions: Despite modest participation rates, the German screening colonoscopy programme will lead to substantial reductions in the CRC burden. The reductions will be fully disclosed in the long run only and predominantly affect numbers of incident cases above 75years of age. Screening offers would need to start at younger ages in order to achieve more effective CRC prevention at younger ages.