Colorectal cancer (CRC) ranks third among the most commonly diagnosed cancers worldwide, with wide geographical variation in incidence and mortality across the world. Despite proof that screening can decrease CRC incidence and mortality, CRC screening is only offered to a small proportion of the target population worldwide. Throughout the world there are widespread differences in CRC screening implementation status and strategy. Differences can be attributed to geographical variation in CRC incidence, economic resources, healthcare structure and infrastructure to support screening such as the ability to identify the target population at risk and cancer registry availability. This review highlights issues to consider when implementing a CRC screening programme and gives a worldwide overview of CRC burden and the current status of screening programmes, with focus on international differences. BACKGROUND

Background: ColonCancerCheck (CCC), Canada's first province-wide colorectal cancer screening program, was publicly launched in Ontario in April 2008. The objective of this article is to report on key indicators of CCC Program performance since its inception.Methods: The CCC Program recommends biennial guaiac-based fecal occult blood test (gFOBT) for persons 50 to 74 years of age at average risk for colorectal cancer and colonoscopy for those at increased risk (having one or more first-degree relatives with a diagnosis of colorectal cancer). Opportunistic screening with colonoscopy is available in Ontario. Five data sources were used to compute indicators of program performance during 2008 to 2011. The indicators computed were FOBT participation, overdue for screening, FOBT positivity, positive predictive value (PPV) of FOBT for colorectal cancer, diagnostic follow-up, and colorectal cancer detection rate.Results: In 2011, FOBT participation was 29.8% and 46.8% of the target population was overdue for screening. FOBT positivity was higher among men (5.1%) than women (3.5%), and the PPV of FOBT for cancer was 4.3% in 2011. Follow-up colonoscopy within 6 months of a positive FOBT was completed by 74.6% of Program participants in 2011. The cancer detection rates for FOBT and for colonoscopy in those with a family history were 1.3 per 1,000 and 4.0 per 1,000, respectively, in 2011.Conclusion: These results provide an early indication of Program performance and provide findings relevant to other organized colorectal cancer screening programs.Impact: The greater cancer detection rate in those at increased risk due to family history who undergo colonoscopy screening suggests that a strategy of risk stratification will enhance the impact of FOBT-based screening programs. Cancer Epidemiol Biomarkers Prev; 23(3); 508-15. Ó2014 AACR.