International variation in the prevalence of preclinical colorectal cancer: Implications for predictive values of noninvasive screening tests and potential target populations for screening

Abstract

Screening for colorectal cancer (CRC) is implemented in an increasing number of countries. We aimed to assess international variation in the prevalence of preclinical CRC and the resulting variation in positive and negative predictive values (PPVs, NPVs) of existing and potential CRC screening tests in various countries. Using age- and sex-specific CRC incidence data and transition rates from preclinical to clinical CRC we estimated overall and age- and sex-specific prevalence of preclinical CRC in the target population aged 50-74 years in different parts of the world. These prevalence estimates were used to derive PPVs and NPVs for existing and potential noninvasive screening tests with varying levels of sensitivity and specificity. Within all regions and countries, prevalence strongly increases with age and is higher in men than in women. In addition, major variation was seen between regions and countries, with overall prevalence varying between 1% and 0.1%. As a result, PPVs are expected to strongly vary between approximately 10% for men in high incidence countries, such as Australia and Germany, and 1% for women in low incidence countries, whereas NPVs are expected to be consistently well above 99%. Variation in CRC prevalence profoundly affects expected PPVs of screening tests, and PPVs should be carefully considered when decisions on screening tests and strategies are made for specific populations and health care systems. Here we provide estimates of preclinical CRC and expected PPVs and NPVs of noninvasive screening tests which may enhance the empirical basis for planning of population-based CRC screening strategies.

Colorectal cancer (CRC) screening is implemented in an increasing number of countries, usually in a two-step approach consisting in a noninvasive test followed by colonoscopy in case of a positive result. Prevalence of preclinical colorectal cancer strongly affects screening efficiency, but such data is scarce. Here, the authors provide detailed age- and sex-specific preclinical CRC prevalence estimates for various countries and geographical regions and show their implications on expected positive and negative predictive values of existing and potential noninvasive screening tests. Knowledge of these predictive values should enhance the empirical basis for decisions on CRC screening tests and target populations. This article is protected by copyright. All rights reserved.

from #ENT-AlexandrosSfakianakis via ola Kala on Inoreader http://ift.tt/2uBzrVH