Population-based cervical cancer screening using high-risk HPV DNA test and liquid-based cytology in northern Thailand

Worldwide burden of cervical human papillomavirus (HPV) in women over 50 years with abnormal cytology: a systematic review and meta-analysis

INTRODUCTION

More than half of global cervical cancer cases occur among women older than 50. However, global estimates regarding the human papillomavirus (HPV) prevalence among this population are lacking, especially for women with abnormal cytology. Therefore, we conducted a systematic review and meta-analysis to estimate the worldwide HPV prevalence in women aged 50 and older with abnormal cytology.

METHODS

We searched PubMed, Scopus and Web of Science for quantitative studies reporting any or high-risk (HR)-HPV prevalence for women 50 years and older with abnormal cytology (atypical squamous cells of undetermined significance and higher). We extracted data on world region, subregion, cervical lesion type, recruitment setting, HPV test, year of study conduct and HPV prevalence from the included studies. We assessed the risk of bias of the included studies using a modified Newcastle-Ottawa scale. We estimated the pooled prevalence and 95% CIs of any-HPV and HR-HPV using random-effects models, considering the world regions. Additionally, we estimated the prevalence by HPV type, lesion type and age groups.

RESULTS

Overall, 113 studies met the inclusion criteria, of which 104 were included in the meta-analysis. Among women aged 50 and older with abnormal cytology, the estimated global pooled prevalence of any-HPV from 53 studies, including 14 585 women, was 54.5% (95%CI, 46.0 to 62.8%), and the HR-HPV prevalence from 85 studies, covering 33 672 women, was 43.0% (95%CI, 36.6 to 49.5%). There was a higher HR-HPV prevalence among women with high-grade lesions and women living in the African continent. No major differences in HR-HPV prevalence between the age groups of women over 50 years were found. The most common single HPV types worldwide were 16 and 52, with pooled prevalence estimates of 12.0% (95%CI, 8.0% to 17.7%) and 8.4% (95%CI, 4.4% to 15.4%), respectively.

CONCLUSION

Our findings highlight the relevance of targeted screening interventions among women 50 years and older. To achieve the elimination of cervical cancer, age-inclusive screening strategies should be considered.

PROSPERO REGISTRATION NUMBER

CRD42021241365.

Global prevalence of cervical human papillomavirus in women aged 50 years and older with normal cytology: a systematic review and meta-analysis

BACKGROUND

Given the paucity of up-to-date empirical data on human papillomavirus (HPV) among older women, we aimed to estimate the global HPV prevalence in women aged 50 years and older with normal cytology.

METHODS

In this systematic review and meta-analysis, we searched for quantitative studies (cross-sectional, longitudinal, case-control, randomised control trials) reporting HPV prevalence among women aged 50 years and older with normal cytology published until May 31, 2022, in PubMed, Scopus, and Web of Science. The risk of bias was assessed using a modified Newcastle-Ottawa scale. The pooled prevalence and 95% CIs of any-HPV and high-risk (HR)-HPV were estimated using random-effects models. Geographical differences were assessed in stratified meta-analyses and multiple meta-regression models. The prevalence by 5-year age groups and genotypes was estimated when reported using mixed-effects models. The study protocol was registered with PROSPERO (CRD42021241365).

FINDINGS

From 9099 identified articles, 132 were included in the qualitative synthesis. 91 (68·9%) studies were deemed to have a low risk of bias and 41 (31·1%) a high risk of bias. We estimated a worldwide pooled any-HPV prevalence of 11·70% (95% CI 9·68-13·87) from 73 studies including 41 745 women and an HR-HPV prevalence of 6·45% (5·45-7·53) from 102 studies including 437 228 women. The pooled prevalence varied geographically, with the highest estimates in western Africa (any-HPV: 32·26% [4·53-70·22]; HR-HPV: 16·20% [0·70-45·95]) and central America (any-HPV: 24·50% [9·97-42·93]; HR-HPV: 13·52% [9·48-18·14]), and the lowest in western Europe (any-HPV: 5·98% [3·08-9·77]; HR-HPV: 4·09% [2·37-6·25]) and western Asia (for HR-HPV only: 3·27% [0·00-20·91]). Worldwide, any-HPV prevalence generally decreased with age, from 10·74% (5·84-18·95) at 50-54 years to 3·56% (2·33-5·40) after age 75 years. HR-HPV prevalence decreased from 6·04% (4·33-8·38) at age 50-54 years to 4·61% (3·25-6·51) at 60-64 years, increased again to 6·33% (4·03-9·79) at 65-69 years, and then decreased to 5·28% (2·83-9·63) after age 75 years. HPV types 16 (1·17% [0·67-2·03]) and 53 (0·90% [0·43-1·90]) were the most prevalent globally.

INTERPRETATION

HPV prevalence in women aged 50 years and older with normal cytology varies globally and mostly correlates with the cervical cancer burden. Research on HPV persistence, progression, and cost-effectiveness of HPV testing among older women should be conducted to fully inform future cervical cancer screening policies.

FUNDING

None.

Human papillomavirus genotype distribution in low-grade squamous intraepithelial lesion cytology, and its immediate risk for high-grade cervical lesion or cancer: a single-center, cross-sectional study

Objective

To investigate the distribution of human papillomavirus (HPV) genotypes in low-grade squamous intraepithelial lesion (LSIL) cytology and the immediate risk of cervical intraepithelial neoplasia grade 2 or higher (CIN2+) lesions.

Methods

This prospective cross-sectional study enrolled women aged ≥21 years that were diagnosed with LSIL cytology at Siriraj Hospital (Bangkok, Thailand) during 2017–2019. Anyplex II HPV testing was performed to detect 14 high-risk HPV cases prior to colposcopy-directed biopsy.

Results

In total, 318 patients were included in the final analysis. Of those, 24 (7.5%), 241 (75.8%), 53 (16.7%) were aged 21–25 years, 25–50 years, and ≥50 years, respectively. Eighty-two patients (25.8%) had abnormal screening results within the previous 5 years. High-risk HPV infection was found in 188 patients (59.1%) with 127 (39.9%) having single and 61 (19.2%) having multiple infections. The five most common HPV genotypes were HPV 66 (18.6%), HPV51 (9.7%), HPV58 (9.4%), HPV16 (9.1%), and HPV56 (8.2%). The immediate risk of CIN2+ was 6% in LSIL, regardless of the HPV status, 8% in high-risk HPV-positive LSIL, and 3.1% in high-risk HPV-negative LSIL. When using 6% as the threshold risk for colposcopy, performing reflex HPV testing in LSIL cytology can decrease the number of colposcopies by 40.9%, with an area under the receiver operating characteristic curve of 0.6 (95% confidence interval, 0.5–0.7).

Conclusion

The study findings support the idea that geographic variations affect the HPV genotype. Reflex HPV testing may decrease the number of colposcopies in cytology-based screening regions with a high prevalence of low-carcinogenic HPV.

Prevalence of human papillomavirus by geographical regions, sexual orientation and HIV status in China: a systematic review and meta-analysis

OBJECTIVE

Human papillomavirus (HPV) infection causes multiple cancers in both women and men. In China, both HPV vaccination and cervical cancer screening coverages are low. We aim to investigate the temporal and geographical trends of HPV DNA prevalence in heterosexual men, women, men who have sex with men (MSM) and people living with HIV (PLHIV) in China.

METHODS

We conducted a systematic review, collecting publications in PubMed, Web of Science, China National Knowledge Infrastructure (CNKI) and Wanfang Data from January 2000 to May 2017. A total of 247 studies were selected for this meta-analysis to estimate pooled HPV prevalence, incidence of cervical cancer and risk of infection for subgroups. Meta-regression was applied to identify contributing factors to prevalence heterogeneities.

RESULTS

The national HPV prevalence was 15.6% (95% CI (14.4% to 16.9%)) in women with normal cervical cytology, and Central China had the highest prevalence (20.5% (15.2% to 25.8%)). HPV prevalence in heterosexual men (14.5% (11.3% to 17.7%)) was comparable with that of women (OR=1.09 (0.98 to 1.17)), but HPV prevalence in MSM (59.9% (52.2% to 67.6%)) was significantly higher than that in heterosexual men (OR=8.81 (8.01 to 9.69)). HIV-positive women (45.0% (38.4% to 51.6%)) and HIV-positive MSM (87.5% (82.3% to 90.9%)) had 4.67 (3.61 to 6.03) and 6.46 (5.20 to 8.02) times higher risk of HPV infection than their HIV negative counterparts.

CONCLUSION

HPV infection is prevalent in China, particularly in Central China, in comparison with the global level and neighbouring countries. Targeted HPV vaccination for women, MSM and PLHIV and scale-up of cervical screening for women are priorities in curbing the HPV epidemic in China.

Cytology versus HPV testing for cervical cancer screening in the general population

BACKGROUND

Cervical cancer screening has traditionally been based on cervical cytology. Given the aetiological relationship between human papillomavirus (HPV) infection and cervical carcinogenesis, HPV testing has been proposed as an alternative screening test.

OBJECTIVES

To determine the diagnostic accuracy of HPV testing for detecting histologically confirmed cervical intraepithelial neoplasias (CIN) of grade 2 or worse (CIN 2+), including adenocarcinoma in situ, in women participating in primary cervical cancer screening; and how it compares to the accuracy of cytological testing (liquid-based and conventional) at various thresholds.

SEARCH METHODS

We performed a systematic literature search of articles in MEDLINE and Embase (1992 to November 2015) containing quantitative data and handsearched the reference lists of retrieved articles.

SELECTION CRITERIA

We included comparative test accuracy studies if all women received both HPV testing and cervical cytology followed by verification of the disease status with the reference standard, if positive for at least one screening test. The studies had to include women participating in a cervical cancer screening programme who were not being followed up for previous cytological abnormalities.

DATA COLLECTION AND ANALYSIS

We completed a 2 x 2 table with the number of true positives (TP), false positives (FP), true negatives (TN), and false negatives for each screening test (HPV test and cytology) used in each study. We calculated the absolute and relative sensitivities and the specificities of the tests for the detection of CIN 2+ and CIN 3+ at various thresholds and computed sensitivity (TP/(TP + TN) and specificity (TN/ (TN + FP) for each test separately. Relative sensitivity and specificity of one test compared to another test were defined as sensitivity of test-1 over sensitivity of test-2 and specificity of test-1 over specificity of test-2, respectively. To assess bias in the studies, we used the Quality Assessment of Diagnostic test Accuracy Studies (QUADAS) tool. We used a bivariate random-effects model for computing pooled accuracy estimates. This model takes into account the within- and between-study variability and the intrinsic correlation between sensitivity and specificity.

MAIN RESULTS

We included a total of 40 studies in the review, with more than 140,000 women aged between 20 and 70 years old. Many studies were at low risk of bias. There were a sufficient number of included studies with adequate methodology to perform the following test comparisons: hybrid capture 2 (HC2) (1 pg/mL threshold) versus conventional cytology (CC) (atypical squamous cells of undetermined significance (ASCUS)+ and low-grade squamous intraepithelial lesions (LSIL)+ thresholds) or liquid-based cytology (LBC) (ASCUS+ and LSIL+ thresholds), other high-risk HPV tests versus conventional cytology (ASCUS+ and LSIL+ thresholds) or LBC (ASCUS+ and LSIL+ thresholds). For CIN 2+, pooled sensitivity estimates for HC2, CC and LBC (ASCUS+) were 89.9%, 62.5% and 72.9%, respectively, and pooled specificity estimates were 89.9%, 96.6%, and 90.3%, respectively. The results did not differ by age of women (less than or greater than 30 years old), or in studies with verification bias. Accuracy of HC2 was, however, greater in European countries compared to other countries. The results for the sensitivity of the tests were heterogeneous ranging from 52% to 94% for LBC, and 61% to 100% for HC2. Overall, the quality of the evidence for the sensitivity of the tests was moderate, and high for the specificity.The relative sensitivity of HC2 versus CC for CIN 2+ was 1.52 (95% CI: 1.24 to 1.86) and the relative specificity 0.94 (95% CI: 0.92 to 0.96), and versus LBC for CIN 2+ was 1.18 (95% CI: 1.10 to 1.26) and the relative specificity 0.96 (95% CI: 0.95 to 0.97). The relative sensitivity of HC2 versus CC for CIN 3+ was 1.46 (95% CI: 1.12 to 1.91) and the relative specificity 0.95 (95% CI: 0.93 to 0.97). The relative sensitivity of HC2 versus LBC for CIN 3+ was 1.17 (95% CI: 1.07 to 1.28) and the relative specificity 0.96 (95% CI: 0.95 to 0.97).

AUTHORS' CONCLUSIONS

Whilst HPV tests are less likely to miss cases of CIN 2+ and CIN 3+, these tests do lead to more unnecessary referrals. However, a negative HPV test is more reassuring than a negative cytological test, as the cytological test has a greater chance of being falsely negative, which could lead to delays in receiving the appropriate treatment. Evidence from prospective longitudinal studies is needed to establish the relative clinical implications of these tests.

Influence of Human Papillomavirus Infection on the Natural History of Cervical Intraepithelial Neoplasia 1: A Meta-Analysis

Objective

To provide a scientific basis for the prevention and treatment of cervical intraepithelial neoplasia grade 1 (CIN1). This study evaluated the impact of human papillomavirus (HPV) infection on the natural history of CIN1.

Methods

Electronic databases of Cochrane Library, EMBASE, PubMed, CNKI, CBM, and Wanfang were searched in April 2016. The eligibility criteria were documented by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We used the Newcastle-Ottawa scale (NOS) to assess study quality.

Results

Thirty-eight studies out of 3,246 identified papers were eligible for inclusion. The risk of CIN1 progression (relative risk [RR]: 3.04; 95% confidence interval [CI]: 2.41–3.83; P < 0.00001) and persistence (RR: 1.48; 95% CI: 1.17–1.87; P = 0.001) was higher in the HPV-positive group than HPV-negative group. Specifically, the risk of CIN1 progression (RR: 13.91; 95% CI: 3.46–55.90; P = 0.000) was higher among persistent high-risk HPV-positive patients and the ratio of CIN1 regression (RR: 0.65; 95% CI: 0.59–0.71; P < 0.00001) was lower in the HPV-positive group than HPV-negative group.

Conclusion

HPV infection resulted in an increased risk of CIN1 progression and decreased disease reversibility. Persistent high-risk HPV infection resulted in a further increased risk of CIN1 progression.

A population-based study of cervical cytology findings and human papillomavirus infection in a suburban area of Thailand

Despite the high incidence of cervical cancer in Thailand, large population-based studies on cervical cytology and HPV prevalence and genotype distribution are rare. This study aimed to determine cervical cytology results and the prevalence and distribution of HPV among Thai females in Bangkhayaeng subdistrict, Pathumthani province, Thailand. Of 4681 female inhabitants, aged 20–70 years, 1523 women finally participated in the study. Cervical samples using liquid-based cytology were collected during February–August 2013 and analyzed for HPV genotype by the LINEAR ARRAY® HPV Genotyping Test (Roche, USA). All participants with abnormal cytology or HPV positivity underwent colposcopy and biopsy. Of 1523 eligible women, 4.1% had abnormal cytology including ASC-US (2.4%), LSIL (1.0%), and HSIL (0.5%). The HPV infection rate was 13.7%. The prevalences of high-risk, probable high-risk, and low-risk HPV types were 5.6%, 3.5%, and 6.8%, respectively. The most common high-risk HPV types detected were HPV-16 (1.31%), HPV-51 (1.25%), and HPV-52 (1.25%). The most common probable high-risk and low-risk HPV types detected were HPV-72 (1.51%), HPV-62 (1.38%), and HPV-70 (1.18%). The rates of CIN2–3 and cancer in this cohort were 1.4% and 0.3%, respectively. In conclusion, HPV prevalence in this study was lower than reported in studies conducted in Western countries or other Asia countries, despite the high prevalence of CIN2 + and cancer. HPV type screening results of the general population in Bangkhayaeng subdistrict were similar to those reported in other countries, with HPV-16 the most common type. However, higher frequencies of HPV-51 and HPV-52 were observed. Despite the availability of a free screening program in this area, the participation rate remains low.

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The largest population-based study using liquid-based cytology and Linear array HPV genotyping in Thailand.

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Low prevalence of high risk HPV in Thailand despite high incidence of cervical cancer.

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Higher ratio of HPV-51, HPV-52 after HPV-16 in this cohort.

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Almost abnormal results underwent colposcopy and biopsy with histological confirmation.

Comparison of Human Papillomavirus Detection in Urine and Cervical Samples Using High-Risk HPV DNA Testing in Northern Thailand

Objective. To evaluate the performance of high-risk human papillomavirus (HPV) DNA testing in urine samples compared to that of cervical sample testing in Northern Thailand. Methods. Paired urine and cervical samples were collected during the follow-up of women with a previous positive HPV test. HPV testing was performed using the Cobas 4800 HPV Test. Linear Array assay was used for genotyping in selected cases. Results. Paired urine and cervical samples were obtained from 168 women. Of 123 paired samples with valid results, agreement in the detection of high-risk HPV DNA was present in 106 cases (86.2%), with a kappa statistic of 0.65 (substantial agreement). Using the cervical HPV results as a reference, the sensitivity of urine HPV testing was 68.6% (24/35) and the specificity 93.2% (82/88). For the detection of histologic high-grade squamous intraepithelial lesion or worse (HSIL+), the sensitivity of urine HPV testing was 80.0% (4/5) and the specificity 78.0% (92/118). Conclusion. Although urine HPV testing had a rather low sensitivity for HPV detection, its sensitivity for histologic HSIL+ detection was high. For clinical use of urine HPV testing, standardization of specimen collection and processing techniques or application of a more sensitive test, especially in the detection of HPV52 and HPV58, is necessary.

Genotyping for Human Papillomavirus (HPV) 16/18/52/58 Has a Higher Performance than HPV16/18 Genotyping in Triaging Women with Positive High-risk HPV Test in Northern Thailand

Background

Testing for high-risk human papillomavirus DNA (HPV test) has gained increasing acceptance as an alternative method to cytology in cervical cancer screening. Compared to cytology, HPV test has a higher sensitivity for the detection of histologic high-grade squamous intraepithelial lesion or worse (HSIL+), but this could lead to a large colposcopy burden. Genotyping for HPV16/18 has been recommended in triaging HPV-positive women. This study was aimed to evaluate the screening performance of HPV testing and the role of genotyping triage in Northern Thailand.

Methods

A population-based cervical screening program was performed in Chiang Mai (Northern Thailand) using cytology (conventional Pap test) and HPV test (Hybrid Capture 2). Women who had abnormal cytology or were HPV-positive were referred for colposcopy. Cervical samples from these women were genotyped using the Linear Array assay.

Results

Of 5,456 women, 2.0% had abnormal Pap test results and 6.5% tested positive with Hybrid Capture 2. Of 5,433 women eligible for analysis, 355 with any positive test had histologic confirmation and 57 of these had histologic HSIL+. The sensitivity for histologic HSIL+ detection was 64.9% for Pap test and 100% for Hybrid Capture 2, but the ratio of colposcopy per detection of each HSIL+ was more than two-fold higher with Hybrid Capture 2 than Pap test (5.9 versus 2.8). Genotyping results were available in 316 samples. HPV52, HPV16, and HPV58 were the three most common genotypes among women with histologic HSIL+. Performance of genotyping triage using HPV16/18/52/58 was superior to that of HPV16/18, with a higher sensitivity (85.7% versus 28.6%) and negative predictive value (94.2% versus 83.9%).

Conclusions

In Northern Thailand, HPV testing with genotyping triage shows better screening performance than cervical cytology alone. In this region, the addition of genotyping for HPV52/58 to HPV16/18 is deemed necessary in triaging women with positive HPV test.

Value of PAX1 Methylation Analysis by MS-HRM in the Triage of Atypical Squamous Cells of Undetermined Significance

BACKGROUND

Detection of cervical high grade lesions in patients with atypical squamous cells of undetermined significance (ASCUS) is still a challenge. Our study tested the efficacy of the paired boxed gene 1 (PAX1) methylation analysis by methylation-sensitive high-resolution melting (MS-HRM) in the detection of high grade lesions in ASCUS and compared performance with the hybrid capture 2 (HC2) human papillomavirus (HPV) test.

MATERIALS AND METHODS

A total of 463 consecutive ASCUS women from primary screening were selected. Their cervical scrapings were collected and assessed by PAX1 methylation analysis (MS-HRM) and high-risk HPV-DNA test (HC2). All patients with ASCUS were admitted to colposcopy and cervical biopsies. The Chi- square test was used to test the differences of PAX1 methylation or HPV infection between groups.

RESULTS

The specificity, sensitivity, and accuracy for detecting CIN2 + lesions were: 95.6%, 82.4%, and 94.6%, respectively, for the PAX1 MS-HRM test; and 59.7%, 64.7%, and 60.0% for the HC2 HPV test.

CONCLUSIONS

The PAX1 methylation analysis by MS-HRM demonstrated a better performance than the high-risk HPV-DNA test for the detection of high grade lesions (CIN2 +) in ASCUS cases. This approach could screen out the majority of low grade cases of ASCUS, and thus reduce the referral rate to colposcopy.

Performance of HPV DNA testing with hybrid capture 2 in triaging women with minor cervical cytologic abnormalities (ASC-US/LSIL) in Northern Thailand

BACKGROUND

Minor cervical cytologic abnormalities include atypical squamous cells of undetermined significance (ASC-US) and low-grade squamous intraepithelial lesion (LSIL). Approximately 10-20% of women with minor cytologic abnormalities have histologic high-grade squamous intraepithelial or worse lesions (HSIL+). In Thailand, women with minor cytologic abnormalities have a relatively high risk of cervical cancer, and referral for colposcopy has been suggested. A triage test is useful in the selection of women at risk for histologic HSIL+ to reduce the colposcopy burden. The aim of this study was to assess the performance of high-risk HPV DNA test in triage of women with minor cytologic abnormalities in northern Thailand.

MATERIALS AND METHODS

All women with ASC-US/LSIL cytology who were referred to our colposcopy clinic from October 2010 to February 2014 were included. HPV DNA testing was performed using Hybrid Capture 2 (HC2). All patients received colposcopic examination. Accuracy values of HC2 in predicting the presence of histologic HSIL+ were calculated.

RESULTS

There were 238 women in this study (121 ASC-US and 117 LSIL). The HC2 positivity rate was significantly higher in the LSIL group than in ASC-US group (74.8% versus 41.0%, p<0.001). Histologic HSIL+ was detected in 9 women (7.4%) in the ASC-US group and 16 women (13.7%) in the LSIL group (p=0.141). There was no histologic HSIL+ detected among HC2-negative cases (sensitivity and negative predictive value of 100%). The performance of HC2 triage was highest among women aged >50 years with ASC-US cytology. An increase in the cut-off threshold for positive HC2 resulted in a substantial decrease of sensitivity and negative predictive value.

CONCLUSIONS

HPV DNA testing with HC2 shows very high sensitivity and negative predictive value in triage of women with minor cervical cytologic abnormalities in northern Thailand. An increase of the cut-off threshold for HC2 triage is not recommended in this region.

High performance of combined HPV testing and genotyping for HPV16/18/52/58 in triaging women with minor cervical cytological abnormalities in northern Thailand

Human papillomavirus (HPV) infection is an important cause of cervical cancer. Screening with cytology or combined cytology and HPV testing helps to detect early cervical cancers and precancerous lesions (high-grade squamous intraepithelial lesion or worse [HSIL+]). Minor cytological abnormalities (atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesion) account for the majority of abnormal cervical cytology results, but only 10-20% of women with minor cytological abnormalities have histologic HSIL+. Triage tests are useful to identify the high-risk patients and reduce the colposcopy burden. This study was aimed to evaluate the triage performance of combined HPV DNA testing and genotyping. Cervical samples from women with minor cytological abnormalities, who underwent colposcopy at Chiang Mai University Hospital in northern Thailand between October 2010 and February 2014, were tested for HPV DNA using Hybrid Capture 2 (HC2). Genotyping was performed using Linear Array assay. Of 223 women with cervical histology confirmation, histologic HSIL+ was detected in 25 women (11.2%). The sensitivity, specificity, positive predictive value, and negative predictive value of 3 triage methods for histologic HSIL+ were; 100%, 47.5%, 19.4%, and 100% by HC2 only; 40.0%, 88.4%, 30.3%, and 92.1% by combined HC2 and genotypes HPV16/18; and 96.0%, 75.8%, 33.3%, and 99.3% by combined HC2 and genotypes HPV16/18/52/58. Triage using combined HC2 and genotypes HPV16/18/52/58 showed significantly greater area under the receiver operating curve than the other 2 methods (P < 0.001). Combined HPV DNA testing and genotyping for HPV16/18/52/58 is useful for triaging women with minor cervical cytological abnormalities in northern Thailand.

Manual liquid based cytology for Pap smear preparation and HPV detection by PCR in Pakistan

This study was conducted on female patients with different gynecological problems attending the gynecology out-patient departments of two tertiary care hospitals in Peshawar city of Khyber Pakhtunkhwa, Pakistan between August 2012 and October 2013. The 200 patients had an age range of 21-65 years. Smears were taken with cervical brushes and preserved in preservative medium and processed for manual liquid based cytology (MLBC) for Pap staining. Out of 200 collected samples, 30 samples were found inadequate on cytology. Of the remaining 170 samples, 164 (96.47%) were normal, 5 (2.94%) were of atypical squamous cells of unknown significance (ASCUS) and 1 (0.6%) was of high grade squamous intraepithelial lesion (HSIL). On PCR all the samples were positive for beta globin gene fragment including those reported inadequate on cytology. Out of the 5 ASCUS samples, 2 samples were positive for HPV, one each for HPV 16 and HPV 18, and the rest of the 3 samples were negative for HPV DNA. The 1 sample of HSIL was positive for HPV 16 on PCR. Out of 164 normal samples on cytology, only 1 sample was HPV 16 positive. So overall, 4 (2%) out of 200 samples were positive for HPV DNA, where 3 were HPV 16 (1.5%), and 1 was HPV 18 (0.5%) positive, and thus the ratio of infection with of HPV 16 to HPV 18 was 3:1 in the general population. In conclusion, PCR based HPV detection is a more sensitive method for screening of HPV infection than cytology as sample inadequacy does not affect the results. However, it can be combined with cytology methods in a HPV positive female to achieve the maximum results.