1. Meta-analysis of available studies evaluating the use of fecal immunochemical testing (FIT) for colorectal cancer (CRC) in patients at higher than average personal or familial risk of CRC demonstrated high overall diagnostic accuracy.
2. Detection of advanced neoplasia (AN), in high-risk patients only demonstrated moderate accuracy with lower sensitivity than detection of CRC.
Evidence Rating Level: 2 (Good)
Study Rundown: Colorectal cancer (CRC) remains one of the most common solid organ tumors. Screening measures for detection of CRC has been effective in reducing mortality and morbidity. The gold standard of screening is colonoscopy, but this can be associated with procedural complications and low adherence. Fecal immunochemical testing (FIT) has been shown to be effective as a screening strategy in average risk populations but has not been systematically evaluated in patients at high risk of CRC and advanced neoplasia (AN). The current study was a meta-analysis of available studies evaluating FIT for CRC and AN detection in patients with family history of CRC, or personal history of advanced adenomas/CRC that included colonoscopy as the gold standard comparison. The analysis found that FIT for CRC demonstrated high specificity, sensitivity, and overall diagnostic accuracy. Use of FIT for AN was less sensitive but still had high specificity and moderate diagnostic accuracy. The study found cutoff values of 15 to 25 ug/g demonstrated the best diagnostic utility.
The current study is the first meta-analysis to evaluate the use of FIT for high risk patients and provides good evidence for its use in the place of regular colonoscopy. The main strengths of the study included the pooling of data from smaller studies helping to overcome the low prevalence of CRC and AN. The studies included in the analysis did have heterogeneous methods, bias, and estimations of accuracy, limiting the interpretation of these results. The study did not include those with inflammatory bowel disease (IBD), hereditary nonpolyposis colorectal cancer (HNPCC), or familial adenomatous poplyposis (FAP).
In-Depth [meta-analysis]: This study included studies that reported diagnostic accuracy of FIT for CRC or AN (defined as CRC or adenomas >10mm or with >25% villous component or high grade dysplasia). The study defined high risk patients as those who were asymptomatic yet had family history of CRC or personal history of prior CRC/advanced adenomas. Colonoscopy was used as the gold standard comparison. Data from patients who were symptomatic, or had a history of HNPCC, FAP, or IBD were excluded. A total of 12 studies (11 cross sectional, 1 randomized control trial) were included in the analysis which encompassed data from 6204 participants.
Pooled analysis of FIT for CRC demonstrated sensitivity of 93% (95% CI 53%-99%), specificity of 91% (95% CI 89-92%) with a positive likelihood ratio of 10.30 (95%CI 7.7-13.9), negative likelihood ratio 0.08 (95%CI 0.01-0.75). FIT for AN had a sensitivity of 48% (95%CI 39-57%), specificity of 93% (95%CI 91-94%) with LR+ 6.55 (95%CI 5-8.5) and LR- 0.57 (95% CI 0.48-0.67). Diagnostic accuracy of FIT for CRC had a 0.93 AUC while AN had 0.86 AUC. Cutoff values of 15 to 25 ug/g demonstrated 93% sensitivity and 94% specificity for CRC).
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