Expanded cytological referral criteria for colposcopy in cervical screening: comparison with human papillomavirus testing

Diagnostic Test Accuracy Review of Cytology for Squamous Intraepithelial Lesion and Squamous Cell Carcinoma of Uterine Cervix

BACKGROUND

Even though cervico-vaginal smears have been used as a primary screening test for cervical carcinoma, the diagnostic accuracy has been controversial. The present study aimed to evaluate the diagnostic accuracy of cytology for squamous intraepithelial lesion (SIL) and squamous cell carcinoma (SqCC) of the uterine cervix through a diagnostic test accuracy (DTA) review.

METHODS

A DTA review was performed using 38 eligible studies that showed concordance between cytology and histology. In the DTA review, sensitivity, specificity, diagnostic odds ratio (OR), and the area under the curve (AUC) on the summary receiver operating characteristic (SROC) curve were calculated.

RESULTS

In the comparison between abnormal cytology and histology, the pooled sensitivity and specificity were 93.9% (95% confidence interval [CI], 93.7%-94.1%) and 77.6% (95% CI, 77.4-77.8%), respectively. The diagnostic OR and AUC on the SROC curve were 8.90 (95% CI, 5.57-14.23) and 0.8148, respectively. High-grade squamous intraepithelial lesion (HSIL) cytology had a higher sensitivity (97.6%; 95% CI, 94.7%-97.8%) for predicting HSIL or worse histology. In the comparison between SqCC identified on cytology and on histological analysis, the pooled sensitivity and specificity, diagnostic OR, and AUC were 92.7% (95% CI, 87.3%-96.3%), 87.5% (95% CI, 87.2%-87.8%), 865.81 (95% CI, 68.61-10,925.12), and 0.9855, respectively. Geographic locations with well-organized screening programs had higher sensitivity than areas with insufficient screening programs.

CONCLUSION

These results indicate that cytology had a higher sensitivity and specificity for detecting SIL and SqCC of the uterine cervix during primary screening.

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.

Age-specific prevalence of infection with human papillomavirus in females: a global review

PURPOSE

Global data on age-specific prevalence of human papillomavirus (HPV) infection overall, and for high-risk HPV types 16 and 18, are essential for the future implementation of HPV prophylactic vaccines for cervical cancer prevention.

METHODS

A systematic review of peer-reviewed publications was conducted to summarize worldwide data on genital HPV-DNA prevalence in women. Studies with clear descriptions of polymerase chain reaction or hybrid capture detection assays were included.

RESULTS

A total of 346,160 women were included in 375 studies. Of 134 studies with age-stratified HPV prevalence data (116 low sexual risk populations, 18 high sexual risk populations), over 50% were from Europe and the Middle East (38%) and North America (19%), with smaller proportions from Asia and Australia (21%), Central and South America (11%), and Africa (10%). Across all geographical regions, data on HPV prevalence were generally limited to women over 18 years of age. Consistently across studies, HPV infection prevalence decreased with increasing age from a peak prevalence in younger women (< or =25 years of age). In middle-aged women (35-50 years), maximum HPV prevalence differed across geographical regions: Africa (approximately 20%), Asia/Australia (approximately 15%), Central and South America (approximately 20%), North America (approximately 20%), Southern Europe/Middle East (approximately 15%), and Northern Europe (approximately 15%). Inconsistent trends in HPV prevalence by age were noted in older women, with a decrease or plateau of HPV prevalence in older ages in most studies, whereas others showed an increase of HPV prevalence in older ages. Similar trends of HPV 16 and/or 18 prevalence by age were noted among 12 populations with available data.

DISCUSSION

Genital HPV infection in women is predominantly acquired in adolescence, and peak prevalence in middle-aged women appears to differ across geographical regions. Worldwide variations in HPV prevalence across age appear to largely reflect differences in sexual behavior across geographical regions. Further studies of HPV prevalence in adolescents are needed for all geographic regions.

Diagnostic accuracy of human papillomavirus testing in primary cervical screening: a systematic review and meta-analysis of non-randomized studies

OBJECTIVE

This is a meta-analysis of studies comparing HPV testing to cytology with regard to their accuracy in the detection of underlying high grade cervical intraepithelial neoplasia in primary cervical cancer screening.

METHODS

A systematic review was conducted following the Cochrane Collaboration Guidelines. A systematic search was performed in 8 electronic databases. Strict selection criteria were applied in terms of types of participants, types of interventions and methods to limit verification bias. Where possible we calculated the sensitivity, specificity, positive and negative predictive value of cytology and the HPV test, as well as sensitivity and specificity ratios for the detection of CIN2 or worse. Random effect models were used for pooling accuracy parameters. The results were displayed using forest plots.

RESULTS

We identified 25 studies fulfilling the inclusion criteria. The pooled sensitivity of HC2, PCR, cytology (ASCUS or worse) and cytology (LSIL or worse) was 90%, 80.9%, 72.7% and 61.6%, respectively, and the pooled specificity was 86.5%, 94.7%, 91.9% and 96.0%, respectively. The ratio of the sensitivity of HC2 to cytology (ASCUS) was 1.25 (95% CI=1.20-1.29), and the corresponding specificity ratio was 0.97 (95% CI=0.96-0.98). The ratio of the sensitivity of combination of HC2 and cytology (ASCUS) to HC2 alone was 1.05 (95% CI=1.04-1.06) and the ratio of the specificity 0.95 (95% CI=0.94-0.96). For women over 30 years, the sensitivity of HC2 was 94.8% and the specificity 86.0%.

CONCLUSIONS

Compared to cytology, the HC2 and PCR are substantially more sensitive for prevalent CIN2 or worse but significantly less specific. The combination of HC2 and cytology has the highest sensitivity and lowest specificity. However, reduction of the incidence of or mortality from invasive cervical cancer among HPV screened subjects compared to cytologically screened subjects has not yet been demonstrated.

Elevated levels of tetraploid cervical cells in human papillomavirus-positive Papanicolaou smears diagnosed as atypical squamous cells of undetermined significance

BACKGROUND

Recommendations for the proper treatment of women diagnosed with an equivocal atypical squamous cells of undetermined significance (ASCUS) Papanicolaou (Pap) smear are controversial. To the authors' knowledge, there currently are no methods available that can identify accurately ASCUS/human papillomavirus (HPV)-positive women who have an increased risk of developing progressive cervical lesions without the use of invasive procedures. An additional diagnostic tool is needed to triage women properly who are diagnosed with ASCUS. Numerical chromosomal abnormalities, such as tetraploidy and aneuploidy, frequently accompany cervical carcinoma development and are believed to represent early and important genetic alterations during cervical carcinogenesis. The identification of elevated levels of numerical chromosomal aberrations in women diagnosed with ASCUS Pap smears, therefore, may be of prognostic value.

METHODS

Multiple-probe fluorescence in situ hybridization was used to analyze 1000 cervical epithelial cells from each of 257 women for the presence of numerical chromosomal aberrations.

RESULTS

A statistically significant proportion of women diagnosed with HPV-positive ASCUS had elevated levels of tetraploid cervical cells (5 of 69 women) compared with normal/HPV-negative women (0 of 75 women) (P = 0.02).

CONCLUSIONS

The frequency of numerical chromosomal aberrations in cervical cells obtained from the majority of women diagnosed with an ASCUS Pap smear did not differ significantly from the frequency in women with smears that were diagnosed as normal. However, a modest but statistically significant proportion of women diagnosed as HPV-positive ASCUS did have elevated levels of tetraploid cervical cells, a genetic abnormality often associated with cervical carcinogenesis, suggesting that these women may be at an increased risk of developing more advanced cervical lesions. Given these results, the authors recommend performing additional studies with histologic follow-up.

Adding HPV16 testing to abnormal cervical smear detection is useful for predicting CIN3: a prospective study

BACKGROUND

The aim of this prospective study was to estimate whether adding human papillomavirus 16 (HPV16) testing to abnormal cervical smears is useful in the prediction of cervical intraepithelial neoplasia 3 (CIN3).

METHODS

Between October 1994 and May 1996, a total of 207 patients at the Akita University Hospital had abnormal smears. Of these patients, 153 patients with CIN1,2 or atypical squamous cells of undetermined significance (ASCUS) were enrolled in this study and followed until June 2001. At the initial visit, a cervical swab was collected for cytology and for HPV16 testing using nested polymerase chain reaction (PCR). When the HPV16 test was positive, HPV16 testing was performed every 3 to 6 months. We compared the prevalence of progression to CIN3 between the HPV16-positive group (n = 16) and the HPV16-negative group (n = 137). We also investigated the risk of progression to CIN3 associated with persistent HPV16 infection.

RESULTS

At the end of the study period, four patients (25%) in the HPV16-positive group developed CIN3, and all of these patients were found to have persistent HPV16 infection during this period. Only three patients (2.2%) in the HPV16-negative group developed CIN3.

CONCLUSIONS

The prevalence of progression to CIN3 in the HPV16-positive group was significantly higher than that in the negative group (p = 0.0023). The odds ratio of progression to CIN3 was 14.9 [95% confidence interval (CI) 2.98-74.4]. In particular, the risk of progression to CIN3 increased with persistent HPV16 infection. Adding HPV16 testing when abnormal cervical smears are detected promises to be useful for predicting CIN3.

Human papillomavirus viral load in predicting high-grade CIN in women with cervical smears showing only atypical squamous cells or low-grade squamous intraepithelial lesion

CONTEXT

Human papillomavirus (HPV) viral load may have an important role in predicting high-grade cervical intraepithelial neoplasia (CIN) in women with cervical smears showing atypical squamous cells or LSIL.

OBJECTIVE

To determine whether the assessment of the viral load of high-risk HPV DNA is useful in predicting the detection of high-grade cervical intraepithelial neoplasia (CIN2 and 3) in women referred because of cervical smears showing only atypical squamous cells or LSIL.

TYPE OF STUDY

Cross-sectional.

SETTING

Colposcopy Clinic in a University hospital.

METHODS

A series of 119 women referred because of atypical squamous cells or LSIL between August 2000 and April 2001 were included. All women were subjected to a new cervical smear, HPV testing for the high-risk types using hybrid capture II (HCII), viral load measurement in relative light units (RLU) and colposcopy, with cervical biopsies (n = 97). Cervical lesions were graded using the CIN classification.

RESULTS

Cervical biopsies revealed CIN2 or CIN3 in 11% of the cases, equally among women referred because of atypical squamous cells or LSIL. The HCII test was positive in 16% of women with atypical squamous cells and 52% of those with LSIL (OR = 5.8; 95% CI 1.4 to 26.7). There was strong correlation between CIN2 or CIN3 and positivity for HPV DNA when this group was compared with women with only CIN1 or normal cervix (OR = 7.8; 95% CI 1.5 to 53.4). In ROC analysis for HCII in diagnosing CIN2 and CIN3, the area under the ROC curve was 0.784, and the viral load cutoff point of 10.0 RLU/cutcuff presented 77% sensitivity and 73% specificity. Second cytology showing at least atypical squamous cells did not accurately detect CIN2 or CIN3 (OR = 6.4; 95% CI 1.0 to 50.9). The sensitivities of the second cervical smear and HCII were similar, although the specificity of HCII was significantly higher than the second cervical smear.

CONCLUSIONS

The viral load of high-risk HPV types was significantly associated with the diagnosis of CIN2 or CIN3 in women referred because of atypical squamous cells and LSIL abnormalities in their cervical smear.