Review for 10.1186/s12876-024-03292-x (2024)

Title: PREDICTIVE VALUES OF AN IMMUNOLOGICAL FECAL OCCULT BLOOD
TEST FOR THE DIAGNOSIS OF COLORECTAL CANCER COMPARED USING
COLONOSCOPY IN SYMPTOMATIC PATIENTS IN YAOUNDE (CAMEROON)
Version: 5 Date: 13 Jan 2024
Reviewer:  Hiroshi Mihara
Reviewer's report:
Thank you for the opportunity to peer review this manuscript.
Major
#1 Despite its advantages, the interest in the use of iFOB tests for CRC diagnosis in SSA has
been sparsely studied. The Lancet review "Colorectal cancer screening in sub-Saharan Africa"
reveals that in Lagos urban area, the number of positive fecal immunochemical tests was lower
compared to other regions in Nigeria. The positivity rates were 11% in Lagos (51 out of 455
people, 95% CI 10-12), 20% in Osun (215 out of 1052 people, 95% CI 20-21), and 28% in
Kwara (166 out of 597 people, 95% CI 27-29). It would be beneficial to include an overview of
the iFOB test conducted in South Africa, to understand the similarities and differences, and to
clarify what novel aspects are present in this study conducted in Cameroon.
#2 The title and abstract should clearly state that the study examines the accuracy of iFOB in
detecting colorectal cancer in symptomatic patients, to avoid misunderstanding that it involves
asymptomatic healthy individuals.
Minor
#1 In the end, was there no impact from worm digestive infections like schistosomiasis? This
should be discussed.
#2 The manuscript states that "The prevalence of CRC is increasing in sub-Saharan African
(SSA) countries," but could you specify to what extent? Is colorectal cancer present even at one
year of age? With a life expectancy of 50-60 years, a faster colonoscopy might be necessary.
Understanding the age range of colorectal cancer occurrence could help narrow down the age
group for fecal occult blood testing and subsequent colonoscopy. The inclusion of one-year-olds
suggests a need for age criteria in your enrollment standards.
#3 The following sentence seems grammatically incorrect: "They are Clear, easy-to-interpret
results It is a useful aid to detect bleeding caused by a number of gastrointestinal disorders, such
as diverticulitis, colitis, polyps, and colorectal cancer."
#4 For CRC detection, it has a sensitivity of 93.6% and a specificity of 99.1%. This seems
exceptionally high. Could you please provide the reference for this data?
#5 Regarding the diagnostic value of the iFOB test, we observed a poor PPV estimated at only
31.1% to predict CRC at colonoscopy and an anatomopathologic examination. However, PPVs
for asymptomatic patients are typically around 7-30.0%, so 30% seems reasonable.
#6 Were the endoscopists blinded to the iFOBT results?
#7 In our study, we conducted the test in patients of any age who already had an indication for
colonoscopy. Was there a specific rationale for including minors in the study, given that consent
procedures differ for them? If there is evidence of a high prevalence of colorectal cancer in the
young, it might be justified.
#8 It might be better to clarify that there is overlap in the indications for colonoscopy. The total
can exceed 100%.
#9 Shouldn't the phrase "Lesions observed after the colonoscopy" be "during the colonoscopy"?
#10 Who determined the presence of visible blood in stools? How was it ensured that this
assessment was accurate? Are there photos? What was the procedure in case of discrepancy in
judgments among multiple observers?
#11 A sub-analysis by age group would be beneficial. Was colorectal cancer present in the
teenage and twenties age groups? At what age was it most prevalent?