A comparative study of faecal occult blood kits in a colorectal cancer screening program in a cohort of healthy construction workers

Repeat Faecal Immunochemical Testing for Colorectal Cancer Detection in Symptomatic and Screening Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Faecal immunochemical testing (FIT) is widely used in bowel screening programmes and assessing symptomatic patients for suspected colorectal cancer (CRC). The evidence for single test performance of FIT in both settings is considerable; however, the use of a repeat test to increase sensitivity remains uncertain. We aimed to review what increase in test positivity would be generated by additional FITs, whether a repeated FIT detects previously missed CRC and advanced colorectal neoplasia (ACRN), and to estimate the sensitivity of double-FIT strategies to diagnose CRC and ACRN.

METHODS

A systematic search of MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) was performed using key search terms. Studies reporting the use of more than one FIT in the same screening round or planned assessment of a single symptomatic patient episode were included. Studies were categorised by the reported study population into asymptomatic, mixed (cohorts of combined asymptomatic, symptomatic, or high-risk surveillance), or symptomatic cohorts.

RESULTS

A total of 68 studies were included for analysis (39 asymptomatic, 21 mixed, 7 symptomatic, and 1 study with discrete asymptomatic and symptomatic data). At a threshold of 10 µg Hb/g, the two-test positivity ranged between 8.1 and 34.5%, with an increase from the second test of 3-9.2 percentage points. Four out of five studies comparing one versus two tests for diagnosing CRC at 10 µg Hb/g identified additional cases with the second test, with a minimum of 50% reduction in missed CRC. At a threshold of 20 µg Hb/g, the second test increased the positivity by 1.3-6.7 percentage points, with a two-test positivity of between 5.1 and 25.0%. Using a threshold of 20 µg Hb/g, five out of seven studies had a 25% reduction in missed CRC. A meta-analysis estimated the double-FIT sensitivity at 10 µg Hb/g for CRC in mixed-risk and symptomatic cohorts to be 94% and 98%, respectively.

CONCLUSIONS

Repeated use of FIT helps to diagnose more cases of CRC with a moderate increase in positivity. A double-FIT strategy at 10 µg Hb/g in mixed and symptomatic cohorts has a very high sensitivity for CRC.

New molecular diagnosis and screening methods for colorectal cancer using fecal protein, DNA and RNA

Several screening methods for reducing the mortality rate of colorectal cancer (CRC) have been reported in recent decades. Fecal occult blood tests (FOBTs) are widely used for CRC screening and immunochemical FOBTs perform better than guaiac FOBTs; however, the sensitivity and specificity of immunochemical FOBTs remain unsatisfactory. To resolve this problem, novel fecal molecular methods based on fecal protein, DNA and RNA analyses have been developed. Regarding fecal proteins, several marker proteins indicating intestinal bleeding and cancer cell-specific proteins have been investigated. Regarding fecal DNA, numerous gene mutation and gene methylation analyses have been reported. Consequently, fecal DNA analysis was recommended as a CRC screening method in 2008. In addition, gene expression analyses of CRC-specific genes and miRNAs in fecal RNA have been investigated over the last decade. This review article summarizes molecular methods using fecal samples for CRC screening, focusing on reports within the last 5 years.

Is faecal-immunochemical test useful in patients with iron deficiency anaemia and without overt bleeding?

BACKGROUND

Both upper and lower endoscopies are indicated in patients with iron deficiency anaemia. However, these examinations are negative in a high proportion of cases.

AIMS

To assess whether faecal-immunochemical test (FIT) may be useful in selecting patients at higher risk of bleeding lesions in iron deficiency anaemia patients.

METHODS

Iron deficiency anaemia patients without overt bleeding were prospectively enrolled. All patients performed FIT, and underwent both upper and lower endoscopy. Predictive factors of potential bleeding lesions were evaluated at multivariate analysis.

RESULTS

FIT was positive in 48 (34.3%) out of 140 enrolled patients, and a potential bleeding lesion was present in 63 (45%) patients. An endoscopic lesion was detected more frequently in FIT-positive than -negative patients (79.2% vs 27.2%; p<0.0001), at both upper endoscopy (52.1% vs 18.5%; p=0.0002) and colonoscopy (33.3% vs 8.7%; p=0.001). At multivariate analysis, FIT was found to be an independent predictor of both bleeding lesions (OR=9.5; 95% CI: 4.1-22; p<0.001) and cancer (OR=4.0, CI: 1.1-15; p=0.029).

CONCLUSIONS

FIT positive-iron deficiency anaemia patients without overt bleeding are at increased risk to present with a bleeding lesion at endoscopy, including cancer. FIT positivity in this setting could be useful to prioritize urgent endoscopy.