Feasibility and performance of the fecal immunochemical test (FIT) for average-risk colorectal cancer screening in Nigeria

Predictive values of an immunological fecal occult blood test for the diagnosis of colorectal cancer compared using colonoscopy in symptomatic patients in Yaounde (Cameroon)

INTRODUCTION

The predictive value of immunological fecal occult blood (iFOB) testing for the screening of colorectal cancer has been well described in the Western world. However, its relevance in Sub-Saharan Africa (SSA) is not well evaluated. It could be altered by the other causes of lower gastrointestinal bleeding such as parasitic infections. The aim of this study was to highlight the performance of an iFOB test for the prediction of colorectal cancer (CRC) during colonoscopy in SSA.

METHODOLOGY

We conducted an analytical cross-sectional study in two digestive endoscopic centers of Yaoundé (Cameroon) from the 1st July to the 31 November 2022. Patients presenting with an indication for colonoscopy without any overt gastrointestinal bleeding were included. Sociodemographic and clinical data were collected. All consenting patients underwent a qualitative immunologic occult test through the iFOB test before colonoscopy. Data were analyzed using SPSS version 23.0 software. The performance of the iFOB test for the diagnosis of CRC during colonoscopy was evaluated in terms of sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV).

RESULTS

We included 103 patients during the study period with a male predominance and a sex ratio of 1.7. The median age [IQR] was 52 [38-65] years (range 1 - 84 years). The most common colonoscopic lesions were polyps in 23 patients (22.3%), CRC in 17 patients (16.5%) and hemorrhoids in 15 patients (14.6%). Patients testing positive for iFOB test accounted for 43.7% (45 patients). Among these patients, 31.1% (14 patients) had a CRC. The Se of the occult blood test for CRC detection was calculated to be 82.3% (95%CI: 56.7-96.2); the Sp was 63.9% (95% CI: 53-74); the PPV was 31.1% (95% CI: 24-39) and the NPV was 94.8% (95% CI: 86.6-98.1).

CONCLUSION

The iFOB test has a good NPV, but a poor PPV for the diagnosis of CRC in our study.

Barriers and recommendations for colorectal cancer screening in Africa

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer worldwide. The incidence of CRC is rising in low- and middle-income countries but decreasing in high-income countries due to the widespread use of surveillance colonoscopy. In Africa, the implementation of screening programs remains a challenge, even in countries, such as Ghana that have established CRC screening guidelines.

OBJECTIVE

The purpose of this review was to identify the barriers and recommend strategies for implementing CRC screening in African countries.

METHODS

A literature search using PubMed was conducted with the following search terms: colorectal neoplasm, early detection of cancer, mass screening, colonoscopy, faecal occult blood test, faecal immunochemical test (FIT) and Africa. After inclusion and exclusion criteria were applied, a total of 13 articles were reviewed.

RESULTS

The most common barriers reported were limited endoscopic capacity, poor knowledge of CRC and CRC screening, health care factors, cultural factors and sociodemographic factors. Recommendations to increase the availability of CRC screening tests were to include the use of FITs, to provide more training for health care providers, and to expand educational programs for patients, physicians, and religious/community leaders.

CONCLUSION

The primary barrier to screening for CRC in Africa is the limited endoscopic capacity, specifically the lack of infrastructure and trained personnel, which requires systematic changes by governing bodies. In addition, health care professionals should be involved in educating patients about CRC and CRC screening. Further research is needed to clarify the factors related to subtypes of CRC and to explore the feasibility of using FITs in Africa.

The African Research Group for Oncology: A decade fostering colorectal cancer research in Nigeria

The African Research Group for Oncology (ARGO) was formed in 2013 to undertake methodologically rigorous cancer research in Nigeria, and to strengthen cancer research capacity in the country through training and mentorship of physicians, scientists, and other healthcare workers. Here, we describe how ARGO's work in colorectal cancer (CRC) has evolved over the past decade. This includes the consortium's scientific contributions to the understanding of CRC in Nigeria and globally and its research capacity-building program.

Colonoscopy-Related Adverse Events in Patients With Abnormal Stool-Based Tests: A Systematic Review of Literature and Meta-analysis of Outcomes

INTRODUCTION

Colorectal cancer (CRC) screening programs based on the fecal immunochemical test (FIT) and guaiac-based fecal occult blood (gFOBT) are associated with a substantial reduction in CRC incidence and mortality. We conducted a systematic review and comprehensive meta-analysis to evaluate colonoscopy-related adverse events in individuals with a positive FIT or gFOBT.

METHODS

A systematic and detailed search was run in January 2021, with the assistance of a medical librarian for studies reporting on colonoscopy-related adverse events as part of organized CRC screening programs. Meta-analysis was performed using the random-effects model, and the results were expressed for pooled proportions along with relevant 95% confidence intervals (CIs).

RESULTS

A total of 771,730 colonoscopies were performed in patients undergoing CRC screening using either gFOBT or FIT across 31 studies. The overall pooled incidence of severe adverse events in the entire patient cohort was 0.42% (CI 0.20-0.64); I2 = 38.76%. In patients with abnormal gFOBT, the incidence was 0.2% (CI 0.1-0.3); I2 = 24.6%, and in patients with a positive FIT, it was 0.4% (CI 0.2-0.7); I2 = 48.89%. The overall pooled incidence of perforation, bleeding, and death was 0.13% (CI 0.09-0.21); I2 = 22.84%, 0.3% (CI 0.2-0.4); I2 = 35.58%, and 0.01% (CI 0.00-0.01); I2 = 33.21%, respectively.

DISCUSSION

Our analysis shows that in colonoscopies performed after abnormal stool-based testing, the overall risk of severe adverse events, perforation, bleeding, and death is minimal.

A New Biomarker of Fecal Bacteria for Non-Invasive Diagnosis of Colorectal Cancer

Background

The intestinal flora is correlated with the occurrence of colorectal cancer. We evaluate a new predictive model for the non-invasive diagnosis of colorectal cancer based on intestinal flora to verify the clinical application prospects of the intestinal flora as a new biomarker in non-invasive screening of colorectal cancer.

Methods

Subjects from two independent Asian cohorts (cohort I, consisting of 206 colorectal cancer and 112 healthy subjects; cohort II, consisting of 67 colorectal cancer and 54 healthy subjects) were included. A probe-based duplex quantitative PCR (qPCR) determination was established for the quantitative determination of candidate bacterial markers.

Results

We screened through the gutMEGA database to identify potential non-invasive biomarkers for colorectal cancer, including Prevotella copri (Pc), Gemella morbillorum (Gm), Parvimonas micra (Pm), Cetobacterium somerae (Cs), and Pasteurella stomatis (Ps). A predictive model with good sensitivity and specificity was established as a new diagnostic tool for colorectal cancer. Under the best cutoff value that maximizes the sum of sensitivity and specificity, Gm and Pm had better specificity and sensitivity than other target bacteria. The combined detection model of five kinds of bacteria showed better diagnostic ability than Gm or Pm alone (AUC = 0.861, P < 0.001). These findings were further confirmed in the independent cohort II. Particularly, the combination of bacterial markers and fecal immunochemical test (FIT) improved the diagnostic ability of the five bacteria (sensitivity 67.96%, specificity 89.29%) for patients with colorectal cancer.

Conclusion

Fecal-based colorectal cancer-related bacteria can be used as new non-invasive diagnostic biomarkers of colorectal cancer. Simultaneously, the molecular biomarkers in fecal samples are similar to FIT, have the applicability in combination with other detection methods, which is expected to improve the sensitivity of diagnosis for colorectal cancer, and have a promising prospect of clinical application.