Effect of Sex, Age, and Positivity Threshold on Fecal Immunochemical Test Accuracy: A Systematic Review and Meta-analysis

Fecal Immunochemical Test: The World's Colorectal Cancer Screening Test

The fecal immunochemical test (FIT) is a tool used for colorectal cancer screening and its use is growing rapidly. FIT, applied as a qualitative or quantitative test, has far better sensitivity for hemoglobin than older, guaiac fecal occult blood tests. This translates into several advantages of FIT, including ability to screen using only 1 stool sample per cycle. This article reviews current understanding of FIT performance as a 1-time test and when applied programmatically. It outlines how to apply the test at the patient level and track performance at the program level. Future prospects for FIT application are highlighted.

Refinement and validation of the IDIOM score for predicting the risk of gastrointestinal cancer in iron deficiency anaemia

OBJECTIVE

To refine and validate a model for predicting the risk of gastrointestinal (GI) cancer in iron deficiency anaemia (IDA) and to develop an app to facilitate use in clinical practice.

DESIGN

Three elements: (1) analysis of a dataset of 2390 cases of IDA to validate the predictive value of age, sex, blood haemoglobin concentration (Hb), mean cell volume (MCV) and iron studies on the probability of underlying GI cancer; (2) a pilot study of the benefit of adding faecal immunochemical testing (FIT) into the model; and (3) development of an app based on the model.

RESULTS

Age, sex and Hb were all strong, independent predictors of the risk of GI cancer, with ORs (95% CI) of 1.05 per year (1.03 to 1.07, p<0.00001), 2.86 for men (2.03 to 4.06, p<0.00001) and 1.03 for each g/L reduction in Hb (1.01 to 1.04, p<0.0001) respectively. An association with MCV was also revealed, with an OR of 1.03 for each fl reduction (1.01 to 1.05, p<0.02). The model was confirmed to be robust by an internal validation exercise. In the pilot study of high-risk cases, FIT was also predictive of GI cancer (OR 6.6, 95% CI 1.6 to 51.8), but the sensitivity was low at 23.5% (95% CI 6.8% to 49.9%). An app based on the model was developed.

CONCLUSION

This predictive model may help rationalise the use of investigational resources in IDA, by fast-tracking high-risk cases and, with appropriate safeguards, avoiding invasive investigation altogether in those at ultra-low predicted risk.

Benefits of switching from guaiac-based faecal occult blood to faecal immunochemical testing: experience from the Wallonia-Brussels colorectal cancer screening programme

Background

Faecal immunochemical tests (FITs) have replaced guaiac-based faecal occult blood test (gFOBTs) in several colorectal cancer (CRC) screening programmes. We aimed to evaluate the benefits of this transition based on the Wallonia–Brussels-organised CRC screening programme.

Methods

A total of 1,569,868 individuals aged 50–74 years, who were invited to screening during 2009–2017, were studied by linking their screening records with insurance, pathology and cancer data in the Belgian Cancer Registry. We compared neoplasm detection rates and positive predictive values (PPVs) of gFOBT and FIT at 15 µg haemoglobin per gram cut-off in screen-naive individuals. We furthermore examined the incidence rates of interval cancer in gFOBT- and FIT-based screening programme.

Results

Advanced neoplasms were detected less frequently by gFOBT (0.8%) than by FIT (1.3%), with a difference of 0.5% (P < 0.01). PPVs were lower for gFOBT (15.1%) than for FIT (21.7%) for advanced neoplasms (difference 6.6%, P < 0.01). Compared to participants with negative gFOBT, those with negative FIT were 77% less likely to develop interval cancer (incidence rate ratio 0.23, 95% confidence interval 0.16–0.33).

Conclusion

Our study demonstrated that in an organised CRC screening programme, replacing gFOBT with FIT improved neoplasm detection rate and substantially reduced interval cancer incidence.

Prevalence of gastrointestinal malignancy in iron deficiency without anaemia: A systematic review and meta-analysis

BACKGROUND

Iron deficiency anaemia is associated with gastrointestinal (GI) malignancy and is an indication for GI investigations. However, the relevance of iron deficiency without anaemia (IDWA) and the underlying risks of GI malignancy are uncertain. Therefore, the aim of this study was to estimate the prevalence of GI malignancy in patients with IDWA overall and in clinically relevant subgroups.

METHODS

We searched MEDLINE and EMBASE for studies that reported on the prevalence or risk of GI malignancy in patients with confirmed IDWA. We performed a random effects meta-analysis of proportions and assessed statistical heterogeneity using the I² statistic.

RESULTS

A total of 1923 citations were screened and 5 studies (4 retrospective cohorts, 1 prospective cohort) comprising 3329 participants with IDWA were included in the meta-analysis. Overall pooled random-effects estimates for prevalence of GI malignancy in those with IDWA were low (0.38%, 95% CI 0.00%-1.84%, I2 = 87.7%). Older patients (2.58%, 95% CI 0.00%-8.77%); non-screening populations (2.45%, 95% CI 0.16%-6.39%) and men and post-menopausal women (0.90%, 95% CI 0.11%-3.23%) with IDWA were at increased risk of GI malignancy compared to younger patients (0.00%, 95% CI 0.00%-0.21%); screened populations (0.24%, 95% CI 0.00%-1.10%) and pre-menopausal women (0.00%, 95% CI 0.00%-1.05%).

CONCLUSION

Overall, IDWA is associated with a low risk of GI malignancy. Older patients and non-screening populations are at elevated risk and require GI investigations. Those not in these subgroups have a lower risk of GI malignancy and may wish to be monitored following discussion of the risk and potential benefits of GI investigations.

A risk-stratified approach to colorectal cancer prevention and diagnosis

Population screening and endoscopic surveillance are used widely to prevent the development of and death from colorectal cancer (CRC). However, CRC remains a major cause of cancer mortality and the increasing burden of endoscopic investigations threatens to overwhelm some health services. This Perspective describes the rationale for and approach to improved risk stratification and decision-making for CRC prevention and diagnosis. Limitations of current approaches will be discussed using the UK as an example of the challenges faced by a particular health-care system, followed by discussion of novel risk biomarker utilization. We explore how risk stratification will be advantageous to current health-care providers and users, enabling more efficient use of limited colonoscopy resources. We discuss risk stratification in the setting of population screening as well as the surveillance of high-risk groups and investigation of symptomatic patients. We also address challenges in the development and validation of risk stratification tools and identify key research priorities.