Colorectal Cancer: A Systematic Review of the Current Situation and Screening in North and Central Asian Countries.

Abstract

The prevalence of colorectal cancer (CRC) is increasing in the past few decades. A significant proportion of this increase is from low to middle income countries (LMIC). CRC prevalence is also increasing in North and Central Asian Countries (NCAC). Screening for colorectal cancer has decreased CRC mortality but data regarding screening practices in NCAC is limited. A literature search was conducted in PubMed/Medline, Embase and Cochrane for current colorectal cancer screening practices in NCAC. Incidence and mortality rates were derived from public health agency websites to calculate age-standardized CRC mortality-to-incidence ratios. Web-based online break-point testing defined as statistical major changes in CRC mortality trends was completed. Among the 677 screened studies, 37 studies met the criteria for inclusion for review. CRC screening in NCAC is not organized, although most countries have cancer registries. The data availability is scarce, and most data is prior to 2017. Most studies are observational. There is minimal data about colonoscopy preparations, adenoma detection and complications rates. The polyp detection rates (PDRs) and adenoma detection rates (ADRs) seem low to optimal in this region. Commonly measured outcomes include participation rate, fecal immunochemical tests (FIT) positivity rate and cost-benefit measures. Lower mortality-to-incidence ratios is seen in countries with screening programs. Kazakhstan and Lithuania with screening programs have achieved breakpoint suggesting major changes in CRC mortality trends. Data about CRC screening varies widely within NCAC. High human developmental index (HDI) countries like Lithuania and Estonia have higher incidence of CRC and mortality. Seven NCAC have CRC screening programs with most utilizing non-invasive methods for screening. Data collection is regional and not organized. The ADR and PDR are low to optimal in this region and cancer detection rates are comparable to other high-income countries (HIC).CRC detection rate is 0.05% for screening in Kazakhstan and 0.2% for screening in Lithuania. Very limited information is available on the actual cost and logistics of implementing a CRC screening program. All NCAC have a cancer registry, with some having a high-quality registry showing national coverage with good validity and completeness.Establishing guideline-based registries and increasing screening efficacy could improve CRC outcomes in NCAC.