Title: Cervical Cancer Screening: A Comparative Study of TruScreen vs. Pap Smear.
Version: 2 Date: 07 Dec 2024
Reviewer:  Sveinung Wergeland Sørbye
Reviewer's report:
Alhudhud et al. have investigated the performance of the real-time optoelectronic device
TruScreen™ (TS) compared to Liquid Based Cytology (LBC), or Pap Smear, for cervical cancer
screening. The study, a prospective observational study involving 507 women at gynecology
clinics, assessed TS and LBC screening methods. With 30 women (5.9%) showing abnormal
TS results and 9 women (1.8%) showing abnormal cytology results, the study suggested TS as a
potential standalone screening tool. The key findings indicated that TS could effectively identify
high-grade cervical lesions (CIN2+), with both women identified with such lesions showing
abnormalities in TS and LBC tests. The conclusion highlighted TS's capacity for providing real-
time, accurate screening results without the need for laboratory infrastructure, suggesting its
suitability for widespread cervical cancer screening.
Comments
1. The study's design does not allow for the calculation of sensitivity for TruScreen and Pap
smear, as only women with abnormal findings were referred for colposcopy and biopsy. This
design inherently ensures that all women diagnosed with CIN2+ must have tested positive with
either TruScreen or Pap smear. Notably, the two women with confirmed high-grade lesions
(CIN2+) were positive on both TruScreen and had abnormal Pap smears (ASC-US+).
2. The detection rate of high-grade cervical lesions (CIN2+) in this study is relatively low at
0.4% (2 out of 507 women). For comparison, a study conducted by Kaiser Permanente reported
a detection rate of 0.7% (2,310 out of 331,818 women).
Katki HA, Kinney WK, Fetterman B, Lorey T, Poitras NE, Cheung L, Demuth F, Schiffman
M, Wacholder S, Castle PE. Cervical cancer risk for women undergoing concurrent testing
for human papillomavirus and cervical cytology: a population-based study in routine clinical
practice. Lancet Oncol. 2011 Jul;12(7):663-72. doi: 10.1016/S1470-2045(11)70145-0.
3. The positivity rate for Pap smear (ASC-US+) in this study is 1.8% (9 out of 507), which
is considerably lower compared to the 3.8% (12,641 out of 331,818) reported in a Kaiser
Permanente study. Interestingly, the positivity rate for TruScreen in this study is 5.9% (30 out
of 507), aligning more closely with the HPV positivity rate of 5.1% (16,757 out of 331,818)
observed in the same Kaiser Permanente study.
4. Cervical cancer screening via cytology shows notable accuracy limitations, highlighted by
moderate observer agreement and a trade-off between sensitivity and specificity. This implies
that hospitals with high detection rates might achieve greater sensitivity for CIN2+ at the expense
of specificity. In the ATHENA study, the positivity rate for primary cytological screening ranged
from 3.8% to 9.9%, while the HPV DNA test (Cobas 4800) showed rates from 10.9% to 13.4%.
Cytology's sensitivity in this study varied between 42.0% and 73.0%. In contrast, the Kaiser
Permanente study reported cytology sensitivity at 53.1% with a 3.8% positivity rate. Given the
even lower positivity rate of 1.8% in Alhudhud et al.'s study, the sensitivity of cervical cytology
in Saudi Arabia might be lower than 53.1%.
Sørbye SW, Suhrke P, Revå BW, Berland J, Maurseth RJ, Al-Shibli K. Accuracy of cervical
cytology: comparison of diagnoses of 100 Pap smears read by four pathologists at three hospitals
in Norway. BMC Clin Pathol. 2017 Aug 29;17:18. doi: 10.1186/s12907-017-0058-8. PMID:
28860942; PMCID: PMC5576325.
Wright TC Jr, Stoler MH, Behrens CM, Sharma A, Sharma K, Apple R. Interlaboratory variation
in the performance of liquid-based cytology: insights from the ATHENA trial. Int J Cancer.
2014 Apr 15;134(8):1835-43. doi: 10.1002/ijc.28514. Epub 2013 Oct 29. PMID: 24122508.
5. Histologically confirmed high-grade lesions (CIN2+) should be the gold standard and the
primary endpoint in cervical cancer screening studies. Consequently, calculations of sensitivity
and specificity should exclusively consider CIN2+ as the outcome measure.
CIN2+   CIN1-
TrueScreen Positive      2      28
TrueScreen Negative      0     477
Values:
True Positives (TP): 2
False Negatives (FN): 0
True Negatives (TN): 477
False Positives (FP): 28
Total Population: 507
TrueScreen Positives: 30
CIN2+ Cases: 2
Results:
- Sensitivity: 100.0% (1.00)
- Specificity: 94.5% (0.945)
- Positive Predictive Value (PPV): 6.7% (0.067)
- Negative Predictive Value (NPV): 100.0% (1.00)
- Positivity Rate of TrueScreen: 5.9% (0.059)
- Prevalence of CIN2+: 0.4% (0.004)
6. In Table 2, the authors define 'abnormal cases' to include both CIN1 and glandular hyperplasia.
Firstly, it is important to clarify that hyperplasia does not equate to dysplasia. Secondly,
according to research by Castle et al. (2011), CIN1 does not significantly increase the risk
of developing CIN3 beyond the risk posed by the genotype-specific HPV infection itself.
Therefore, CIN1 should not be the primary target of screening programs, nor is treatment
usually recommended, as it often resolves spontaneously. Additionally, research by Sørbye et al.
(2011) indicates that the risk of developing high-grade lesions (CIN2+) during post-colposcopy
follow-up is comparable between women with a negative cervical biopsy and those with CIN1,
supporting a conservative management approach for CIN1, similar to management of women
with positive HPV tests but normal biopsies.
Castle PE, Gage JC, Wheeler CM, Schiffman M. The clinical meaning of a cervical
intraepithelial neoplasia grade 1 biopsy. Obstet Gynecol. 2011 Dec;118(6):1222-1229. doi:
10.1097/AOG.0b013e318237caf4. PMID: 22105250; PMCID: PMC3229199.
Sørbye SW, Arbyn M, Fismen S, Gutteberg TJ, Mortensen ES. HPV E6/E7 mRNA testing
is more specific than cytology in post-colposcopy follow-up of women with negative cervical
biopsy. PLoS One. 2011;6(10):e26022. doi: 10.1371/journal.pone.0026022. Epub 2011 Oct 6.
PMID: 21998748; PMCID: PMC3188582.
7. The authors state in the introduction, 'The incidence and death rates of cervical cancer were
profoundly elevated (about 85%) in low to middle-income countries, while they accounted for
only 3.6% in developed countries.' It is likely correct that 85% of all cervical cancer cases occur
in low and middle-income countries, but the significance of the 3.6% figure is unclear. Could
you please clarify what this percentage represents?
8. The authors mention that the Pap smear, or conventional cytology, is the most commonly used
test for cervical cancer screening. However, evidence suggests a shift toward HPV testing in
primary screening due to its higher sensitivity. For instance, a cluster-randomized trial in India
demonstrated that HPV testing significantly reduced the incidence of advanced cervical cancers
and deaths compared to cytology and visual inspection with acetic acid (VIA). Specifically, the
HPV testing group showed a reduction in advanced cancer cases and mortality by nearly half
compared to the control group, while no significant reductions were observed with cytology or
VIA. Furthermore, a meta-analysis from Europe and follow-up studies from randomized trials
comparing HPV-based screening with cytology reported that HPV screening offers 60-70%
greater protection against invasive cervical carcinomas. These findings strongly support the
adoption of HPV-based screening, which allows for longer screening intervals and initiates from
age 30, enhancing both efficacy and cost-effectiveness.
Sankaranarayanan R, Nene BM, Shastri SS, Jayant K, Muwonge R, Budukh AM, Hingmire S,
Malvi SG, Thorat R, Kothari A, Chinoy R, Kelkar R, Kane S, Desai S, Keskar VR, Rajeshwarkar
R, Panse N, Dinshaw KA. HPV screening for cervical cancer in rural India. N Engl J Med. 2009
Apr 2;360(14):1385-94. doi: 10.1056/NEJMoa0808516. PMID: 19339719.
Ronco G, Dillner J, Elfström KM, Tunesi S, Snijders PJ, Arbyn M, Kitchener H, Segnan
N, Gilham C, Giorgi-Rossi P, Berkhof J, Peto J, Meijer CJ; International HPV screening
working group. Efficacy of HPV-based screening for prevention of invasive cervical cancer:
follow-up of four European randomised controlled trials. Lancet. 2014 Feb 8;383(9916):524-32.
doi: 10.1016/S0140-6736(13)62218-7. Epub 2013 Nov 3. Erratum in: Lancet. 2015 Oct
10;386(10002):1446. doi: 10.1016/S0140-6736(15)00411-0. PMID: 24192252.
9. I do not believe that TruScreen is suitable as a primary screening tool. Instead, HPV self-
sampling could serve more effectively as the primary screening method, with TruScreen used for
triaging women who test positive for HPV before they are referred for colposcopy and biopsy.
It’s important to note that women with a positive HPV test require follow-up monitoring, even
if their colposcopy results are normal or their biopsy is negative.
https://www.who.int/publications/i/item/WHO-SRH-23.1
10. The authors describe colposcopic assessment as a more accurate diagnostic tool than
traditional cytology, with an estimated sensitivity and specificity of 80% and 92%, respectively,
and consider it cost-effective, especially in resource-poor settings. However, evidence suggests
that colposcopy may not be more sensitive than cytology. According to the NHSCSP Guidelines
for Colposcopy and Programme Management, which govern British practice, the expected
accuracy for colposcopy is around 65%. Further, Zuchna et al. reported a sensitivity of 66.2% for
CIN2+ when using up to three guided biopsies, with the cone specimen as a reference standard.
Massad et al. also reported a sensitivity of just 39% for CIN2+ using digitized cervical images in
women referred for equivocal or minor cytologic abnormalities. Additionally, the low specificity
of colposcopy limits its suitability as a primary screening tool, relegating its use to confirmatory
testing in women with abnormal cytology results.
Desai M, Hadden P, Kitchener H, Martin-Hirsch P, Prendiville W, et al. (2010) Colposcopy and
Programme Management. Guidelines for the NHS Cervical Screening Programme. NHSCSP
Publication No 20 May.
Zuchna C, Hager M, Tringler B, Georgoulopoulos A, Ciresa-Koenig A, et al. (2010)
Diagnostic accuracy of guided cervical biopsies: a prospective multicenter study comparing the
histopathology of simultaneous biopsy and cone specimen. Am J Obstet Gynecol 203: 321–326.
Massad LS, Jeronimo J, Katki HA, Schiffman M (2009) The accuracy of colposcopic grading for
detection of high-grade cervical intraepithelial neoplasia. J Low Genit Tract Dis 13: 137–144.
11. The authors use the term 'CIN II+' to describe women with high-grade lesions. I recommend
using 'CIN2+' instead, as it is the more commonly accepted notation in clinical literature.
12. The authors state that the sample size was calculated based on a CIN2+ prevalence of
5% to 20% at a referral hospital, which is typical for populations with abnormal cytology.
However, this contrasts sharply with prevalences observed in primary screening populations,
where previous findings are typically normal. For example, in the Kaiser Permanente study, the
detection rate of CIN2+ was only 0.7%. Similarly, in the study by Alhudhud et al., the detection
rate was 0.4%. To detect 60 cases of CIN2+ with a prevalence of 0.4%, screening 15,000 women
would be necessary. In comparison, the Kaiser Permanente study included 331,818 women.
The sample size and the prevalence data used by the authors may not accurately reflect the
detection rates achievable in primary screening settings, potentially leading to overestimations
of the screening program's effectiveness.
13. The authors classify various Pap smear results including 'inflammatory/reactive cellular
changes' and 'endometrial cells' alongside traditional abnormal categories. However, according
to the Bethesda classification, only ASC-US, LSIL, and HSIL are considered valid abnormal
diagnoses. Thus, conditions such as inflammatory/reactive changes and presence of endometrial
cells should be classified under 'NILM' (negative for intraepithelial lesion or malignancy), which
indicates a negative result rather than an abnormal one.
14. In the discussion section, the authors claim that 'A growing body of literature has shown
that combining TS with other modalities can yield higher accuracy and reduce the need
for colposcopy. Wei et al. reported that TS had higher sensitivity and specificity than the
Pap smear. Still, when the two were combined, the sensitivity and specificity increased,
which is consistent with our results.' However, the notion of simultaneously increasing both
sensitivity and specificity through the combination of two screening tests involves a fundamental
misunderstanding. Typically, co-testing allows for increased sensitivity if follow-up is pursued
for any positive result (+/-, -/+ or +/+), which inherently decreases specificity due to more false
positives. Conversely, opting for high specificity by only following up on cases where both tests
are positive (+/+) will miss some cases, thus lowering the sensitivity. The trade-off between
sensitivity and specificity must be clearly acknowledged when discussing co-testing strategies.
15. To ensure accurate and efficient peer reviews and simplify the post-review editing
procedures, it is recommended to use a line numbering system for all submitted manuscripts.
Minor revisions
Title, "Cervical Cancer Screening: A Comparative Study of TruScreen vs. Pap Smear"
Abstract, "Objectives: This study aimed to evaluate the potential of the real-time optoelectronic
device TruScreen™ (TS) as an alternative or adjunct to Pap Smear (Liquid Based Cytology,
LBC) for cervical cancer screening.
Method: We conducted a prospective observational study involving 507 women who were
routinely followed at gynecology clinics. All participants underwent TS and LBC examinations
after study enrolment. Those with abnormal findings were referred for colposcopy and cervical
biopsy within one month.
Results: Of the participants, 30 women (5.9%) had abnormal TS findings, and 9 women (1.8%)
had abnormal cytology results. Colposcopy revealed that 13 women (43.3%) had low-grade
colposcopic impressions and one (3.3%) had a high-grade colposcopic impression. Biopsy
confirmed two cases of CIN2+. TS demonstrated a sensitivity of 100.0% and a specificity of
94.5% for detecting cervical neoplasms, which were comparable to the Pap smear’s sensitivity
and specificity of 100.0% and 98.2%, respectively.
Conclusion: TS offers a reliable and practical alternative for cervical cancer screening that
does not require traditional sample collection or laboratory infrastructure, providing real-time
and accurate results. Nevertheless, additional research is required to validate these findings in
broader populations and to assess the effectiveness of TS in conjunction with or as a triage tool
following primary HPV screening."
Introduction, "Worldwide, cervical cancer ranks as the fourth most common cancer and cause
of cancer-related mortality among women."
Introduction, "The incidence and mortality rates of cervical cancer are disproportionately high in
low and middle-income countries, accounting for about 85% of all cases worldwide. Conversely,
these rates are significantly lower in developed countries, representing only a small fraction of
global cases."
Statistical analysis, "The Chi-square test or Fisher's exact test was used to compare the screening
performance of TruScreen (TS) and Pap smear, as appropriate. A p-value of less than 0.05 was
considered statistically significant."
Results, "Overall, 30 women (5.9%) had abnormal TS findings. The distribution of Pap smear
results was as follows: 97.2% were negative for intraepithelial lesion or malignancy (NILM),
1.8% were abnormal (0.6% ASC-US, 0.8% LSIL, 0.4% HSIL), and 1.2% yielded unsatisfactory
samples."
Results, "Thirty women underwent colposcopy, of whom 13 (43.3%) had low-grade colposcopic
impressions, and only one (3.3%) had a high-grade colposcopic impression."
Table 2, delete "Detection of abnormal cases (n =6)", "Detection of CIN I (n =3) " and "Glandular
hyperplasia (n =1) "
For CIN2+ the numbers are:
Values:
True Positives (TP): 2
False Negatives (FN): 0
True Negatives (TN): 477
False Positives (FP): 28
Total Population: 507
TrueScreen Positives: 30
CIN2+ Cases: 2
Results:
- Sensitivity: 100.0% (1.00)
- Specificity: 94.5% (0.945)
- Positive Predictive Value (PPV): 6.7% (0.067)
- Negative Predictive Value (NPV): 100.0% (1.00)
- Positivity Rate of TrueScreen: 5.9% (0.059)
- Prevalence of CIN2+: 0.4% (0.004)
Discussion,  "Several developed countries have witnessed a significant reduction in cervical
cancer incidence and cause-specific mortality over recent years due to the implementation of
national screening protocols" => "Several developed countries have experienced significant
reductions in cervical cancer incidence and cause-specific mortality in recent years, largely due
to the implementation of national screening programs."
add the reference:
Peto J, Gilham C, Fletcher O, Matthews FE. The cervical cancer epidemic that screening
has prevented in the UK. Lancet. 2004 Jul 17-23;364(9430):249-56. doi: 10.1016/
S0140-6736(04)16674-9. PMID: 15262102.
Conclusion, "TruScreen (TS) appears to be a practical, point-of-care alternative for cervical
cancer screening in settings where access to laboratory infrastructure and trained cytologists is
limited. Our findings suggest that TS can provide real-time assessments, potentially broadening
screening coverage and enabling rapid identification of at-risk individuals. Its ability to operate
without traditional sample collection may facilitate the involvement of non-physician personnel
and support more accessible, see-and-treat approaches.
However, these results should be interpreted with caution. The study was conducted under
controlled conditions, and additional research is necessary to confirm TS’s clinical efficacy
across diverse populations and healthcare contexts. Future studies should further evaluate the
trade-offs between sensitivity and specificity, as well as the integration of TS into existing
screening algorithms—particularly when used as a triage method following primary HPV
testing."