Trends in the quality assurance process indicators for Japanese colorectal cancer screening during 2003-13.

Background: Recently, the importance of quality assurance (QA) for cancer screening has gained increasing attention in Japan. This study aimed to evaluate QA process indicators for population-based colorectal cancer screening during 2003-13.

Methods: A national cancer screening database was used to evaluate the following process indicators: the positivity rate, diagnostic follow-up rate, unidentified results rate, non-compliance with diagnostic follow-up rate, cancer detection rate and positive predictive value (PPV).

Results: The positivity rate remained constant at 6.5% until 2011, and then increased slightly thereafter. During 2003-13, the cancer detection rate increased from 0.15% to 0.21%, and the PPV increased from 2.2% to 3.1%. Although the diagnostic follow-up rate increased from 58% to 67%, the non-compliance with diagnostic follow-up rate decreased from 24% to 16% and the unidentified results rate decreased from 18% to 17%.

Conclusions: During the study period, the QA process indicators for colorectal cancer screening in Japan generally improved. However, the recent increase in the positivity rate requires careful observation. Innovative solutions are needed to increase the diagnostic follow-up rate.