Chemical and immunological testing for faecal occult blood in screening subjects at risk of familial colorectal cancer

Diagnostic Accuracy of Fecal Immunochemical Test in Patients at Increased Risk for Colorectal Cancer: A Meta-analysis

IMPORTANCE

The potential role of the fecal immunochemical test (FIT) for screening patients at increased risk for colorectal cancer (CRC) has not yet been elucidated.

OBJECTIVE

To assess the diagnostic accuracy of FIT for CRC or advanced neoplasia (AN) in asymptomatic patients at above-average risk.

DATA SOURCES

MEDLINE, EMBASE, Cochrane Library, and gray literature sources through August 2016.

STUDY SELECTION

Diagnostic studies evaluating the accuracy of FIT for CRC or AN in patients with a personal or familial history of CRC using colonoscopy as the reference standard.

DATA EXTRACTION AND SYNTHESIS

Two authors (A.K. and P.P.) independently extracted data and evaluated study quality using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, and evaluated the quality of the body of evidence by means of GRADE (Grading of Recommendations Assessment, Development, and Evaluation). Hierarchical models were used to synthesize available evidence.

MAIN OUTCOMES AND MEASURES

The primary outcome was the diagnostic performance of FIT for detecting CRC or AN.

RESULTS

We included 12 studies (6204 participants). Seven studies were deemed at high or unclear risk of bias. The average sensitivity of FIT for CRC was 93% (95% CI, 53%-99%), and the average specificity was 91% (95% CI, 89%-92%), yielding a positive likelihood ratio (LR+) of 10.30 (CI 7.7-13.9) and a negative likelihood ratio (LR-) of 0.08 (95% CI, 0.01-0.75) (GRADE: very low). The average sensitivity of FIT for AN was 48% (95% CI, 39%-57%); and the average specificity was 93% (95% CI, 91%-94%), yielding an LR+ of 6.55 (95% CI, 5.0-8.5) and an LR- of 0.57 (95% CI, 0.48-0.67) (GRADE: very low). Subgroup analyses indicated that FIT cutoff values between 15- and 25-μg/g feces provided the best combination of sensitivity and specificity for the diagnosis of CRC (93% and 94%, respectively). Quantitative and 1-sample FIT showed adequate test performance, but data on other FIT brands and multiple samples were insufficient.

CONCLUSIONS AND RELEVANCE

The FIT has high overall diagnostic accuracy for CRC but moderate accuracy for AN in patients at above-average personal or familial risk. Heterogeneity and wide confidence intervals limit the trustworthiness of our findings.

The fecal occult blood test as a tool for improved outpatient qualification for colonoscopy. A single-center experience and 10-year follow-up survey

PURPOSE

Colonoscopy is not widely and easily available in all countries, even for symptomatic patients. This is one of the causes of tumors not being diagnosed until an advanced stage. The aim of this study was to estimate the efficacy of the fecal occult blood test (FOBT) in the diagnostic work-up of outpatients referred to a colorectal unit due to indistinct abdominal symptoms.

PATIENTS/METHODS

Among 10418 consecutive symptomatic individuals referred to the outpatient clinic, an immunochemical FOBT (Hem-Check 1^®) was recommended for 9432 patients with indistinct symptoms as a tool for qualifying them for colonoscopy. All the subjects were treated according to their diagnosis and followed-up for the next 10 years.

RESULTS

Colorectal cancer (CRC) was diagnosed in 535 individuals: 393/986 (39.9%) among patients with red-flag symptoms, and 142/951 (14.9%) of individuals with indistinct symptoms and a positive FOBT. In the latter group, less-advanced tumors, classed as such using Dukes' classification, were twice as common and more advanced CRC occurred twice as seldom than in the former. Cancer recurrence-free and overall survival periods after surgical treatment for CRC were significantly longer in patients with indistinct symptoms who qualified for diagnostic procedures on the basis of a positive FOBT.

CONCLUSIONS

Patients with symptoms suggesting organic colon disease had a worse prognosis compared to individuals with non-specific symptoms. If bowel endoscopy is not widely and easily available, qualification for colonoscopy on the basis of alarm symptoms and a positive FOBT seems to be an effective strategy in early CRC diagnosis.

Faecal immunochemical test accuracy in patients referred for surveillance colonoscopy: a multi-centre cohort study

BACKGROUND

Given the increasing burden on colonoscopy capacity, it has been suggested that faecal immunochemical test (FIT) results could guide surveillance colonoscopy intervals. Against this background, we have evaluated the test accuracy of single and double FIT sampling to detect colorectal cancer (CRC) and/or advanced adenomas in an asymptomatic colonoscopy-controlled high-risk population.

METHODS

Cohort study of asymptomatic high-risk patients (personal history of adenomas/CRC or family history of CRC), who provided one or two FITs before elective colonoscopy. Test accuracy of FIT for detection of CRC and advanced adenomas was determined (cut-off level 50 ng/ml).

RESULTS

1,041 patients provided a FIT (516 personal history of adenomas, 172 personal history of CRC and 353 family history of CRC). Five CRCs (0.5%) and 101 advanced adenomas (9.7%) were detected by colonoscopy. Single FIT sampling resulted in a sensitivity, specificity, PPV and NPV for CRC of 80%, 89%, 3% and 99.9%, respectively, and for advanced adenoma of 28%, 91%, 24% and 92%, respectively. Double FIT sampling did not result in a significantly higher sensitivity for advanced neoplasia. Simulation of multiple screening rounds indicated that sensitivity of FIT for advanced adenoma could reach 81% after 5 screening rounds.

CONCLUSIONS

In once-only FIT sampling before surveillance colonoscopy, 70% of advanced neoplasia were missed. A simulation approach indicates that multiple screening rounds may be more promising in detecting advanced neoplasia and could potentially alleviate endoscopic burden.

Screening for familial colorectal cancer with a sensitive immunochemical fecal occult blood test: a pilot study

OBJECTIVE

Colonoscopy is empirically recommended as the first choice screening strategy in first-degree relatives of patients with colorectal cancer (CRC). However, this strategy is accepted by less than 40% of the risk population and two-thirds of screened individuals and renders a normal exploration. This pilot study assessed the accuracy of a latex agglutination immunochemical fecal occult blood test (LA-FOBT) for detecting advanced colorectal neoplasm (cancer or adenomatous polyps > or =1 cm in size, with villous pattern or high grade dysplasia) in asymptomatic first-degree relatives of patients with CRC.

METHODS

One hundred and sixty-nine first-degree relatives of 135 index cases were prospectively included. All participants received a sensitive LA-FOBT (hemoglobin detection limit of 50 ng/ml buffer), and were invited to undergo colonoscopy. On the whole, 116 (69%) participants returned LA-FOBT and underwent colonoscopy.

RESULTS

LA-FOBT was positive in 19 of 116 (16%) cases. Colonoscopy detected neoplasms in 49 of 116 (42%) patients: 37 of 116 (32%) were nonadvanced adenomas and 12 of 116 (10%) advanced adenomas. LA-FOBT detected 10 of 12 (83%) advanced adenomas showing a sensitivity, specificity, positive predictive value, and negative predictive value of 83, 91, 53, and 98%, respectively. In patients with positive LA-FOBT, 1.9 colonoscopies were necessary for detecting one advanced adenoma, whereas in case of not performing this test 10 colonoscopies would be needed. Overall, approximately 80% of screening colonoscopies could be precluded using a LA-FOBT.

CONCLUSION

One-time screening with LA-FOBT successfully detects advanced colorectal adenomas and may save unnecessary colonoscopies in first-degree relatives of patients with CRC.

Colonoscopy for screening and follow up of patients with a family history of colorectal cancer

OBJECTIVE

To determine the minimum family history of colorectal cancer (CRC), which justifies colonoscopy and to establish whether further colonic assessment is necessary after a negative screening colonoscopy.

METHOD

A retrospective review of every colonoscopy undertaken for family screening at the Royal Berkshire and Battle Hospitals, Reading between October 1996 and July 2004.

RESULTS

Four hundred and thirty-two patients (261 women) with an average age of 48 years (range 14-84) were screened. Three cancers in patients over the age of 60 years and 49 adenomas were found in 37 patients. Twenty three of 281 (8%) patients with a 'low-risk' family history (one in 12 or less lifetime risk of developing CRC) had either a cancer or an adenoma. Eighteen of 151 (12%) patients with a 'high-risk' family history (one in 10 or greater) had a similar positive colonoscopy. Thirteen of 15 patients who had an adenoma aged under 45 years had a high-risk family history. Seventy-three patients subsequently underwent two or more follow-up colonoscopies. There were 22 adenomatous polyps found in 12 patients (16%) at the first screening, nine adenomas in seven patients in the second colonoscopy and four adenomas found in four patients in all subsequent colonoscopies.

CONCLUSION

Patients with a low-risk family history have a similar adenoma pick-up to that of the general population. These patients need not be screened below the age of 50 unless symptomatic. Follow up of low-risk family history (FH) patients with a negative screening colonoscopy is unlikely to be beneficial.

What's new in colorectal cancer screening?

There is now good evidence from case control studies and randomized controlled trials that screening average-risk subjects for colorectal cancer using faecal occult blood tests reduces mortality. There is limited data indicating that screening sigmoidoscopy can also achieve this. There is no evidence yet that screening by colonoscopy or double contrast barium enema can reduce mortality. Calculations of cost-effectiveness suggest that all of the above strategies should be economically worthwhile but there is no convincing evidence to suggest that one strategy is markedly more cost-effective than the others. Further data on several aspects of screening are required before any decisions are made on which form(s) of screening should be offered nationwide.