Synchronous colorectal cancer using CT colonography vs. other means : a systematic review and meta-analysis

Objectives: The objective of our study was to systematically review the evidence about synchronous colorectal cancer diagnosed with or without computed tomography colonography (CTC). Materials and methods: Two systematic searches were performed (PubMed and EMBASE) for studies reporting the prevalence of synchronous colorectal cancer (CRC): one considering patients who underwent CTC and the another one considering patients who did not undergo CTC. A three-level analysis was performed to determine the prevalence of patients with synchronous CRC in both groups of studies. Heterogeneity was explored for multiple variables. Pooled prevalence and 95% confidence interval (CI) were calculated. A quality assessment (STROBE) was done for the studies. Results: For CTC studies, among 2645 articles initially found, 21 including 1673 patients, published from 1997 to 2018, met the inclusion criteria. For non-CTC studies, among 6192 articles initially found, 27 including 111,873 patients published from 1974 to 2015 met the inclusion criteria. The pooled synchronous CRC prevalence was 5.7% (95% CI 4.7%–7.1%) for CTC studies, and 3.9% (95% CI 3.3%–4.4%) for non-CTC studies, with a significant difference (p = 0.004). A low heterogeneity was found for the CTC group (I2= 10.3%), whereas a high heterogeneity was found in the non-CTC group of studies (I2= 93.5%), and no significant explanatory variables were found. Of the 22 STROBE items, a mean of 18 (82%) was fulfilled by CTC studies, and a mean of 16 (73%) by non-CTC studies. Conclusions: The prevalence of synchronous CRC was about 4–6%. The introduction of CTC is associated with a significant increase of the prevalence of synchronous CRCs.