Description of a seven-year prospective study of human papillomavirus infection and cervical neoplasia among 10000 women in Guanacaste, Costa Rica,

Deep Cervix Model Development from Heterogeneous and Partially Labeled Image Datasets

Cervical cancer is a significant disease affecting women worldwide. Regular cervical examination with gynecologists is important for early detection and treatment planning for women with precancers. Precancer is the direct precursor to cervical cancer. However, there is a scarcity of experts and the experts' assessments are subject to variations in interpretation. In this scenario, the development of a robust automated cervical image classification system is important to augment the experts' limitations. Ideally, for such a system the class label prediction will vary according to the cervical inspection objectives. Hence, the labeling criteria may not be the same in the cervical image datasets. Moreover, due to the lack of confirmatory test results and inter-rater labeling variation, many images are left unlabeled. Motivated by these challenges, we propose to develop a pretrained cervix model from heterogeneous and partially labeled cervical image datasets. Self-supervised Learning (SSL) is employed to build the cervical model. Further, considering data-sharing restrictions, we show how federated self-supervised learning (FSSL) can be employed to develop a cervix model without sharing the cervical images. The task-specific classification models are developed by fine-tuning the cervix model. Two partially labeled cervical image datasets labeled with different classification criteria are used in this study. According to our experimental study, the cervix model prepared with dataset-specific SSL boosts classification accuracy by 2.5%↑ than ImageNet pretrained model. The classification accuracy is further boosted by 1.5%↑ when images from both datasets are combined for SSL. We see that in comparison with the dataset-specific cervix model developed with SSL, the FSSL is performing better.

Improving the repeatability of deep learning models with Monte Carlo dropout

The integration of artificial intelligence into clinical workflows requires reliable and robust models. Repeatability is a key attribute of model robustness. Ideal repeatable models output predictions without variation during independent tests carried out under similar conditions. However, slight variations, though not ideal, may be unavoidable and acceptable in practice. During model development and evaluation, much attention is given to classification performance while model repeatability is rarely assessed, leading to the development of models that are unusable in clinical practice. In this work, we evaluate the repeatability of four model types (binary classification, multi-class classification, ordinal classification, and regression) on images that were acquired from the same patient during the same visit. We study the each model's performance on four medical image classification tasks from public and private datasets: knee osteoarthritis, cervical cancer screening, breast density estimation, and retinopathy of prematurity. Repeatability is measured and compared on ResNet and DenseNet architectures. Moreover, we assess the impact of sampling Monte Carlo dropout predictions at test time on classification performance and repeatability. Leveraging Monte Carlo predictions significantly increases repeatability, in particular at the class boundaries, for all tasks on the binary, multi-class, and ordinal models leading to an average reduction of the 95% limits of agreement by 16% points and of the class disagreement rate by 7% points. The classification accuracy improves in most settings along with the repeatability. Our results suggest that beyond about 20 Monte Carlo iterations, there is no further gain in repeatability. In addition to the higher test-retest agreement, Monte Carlo predictions are better calibrated which leads to output probabilities reflecting more accurately the true likelihood of being correctly classified.

The Development of Global Cancer Research at the United States National Cancer Institute

International research and collaboration has been a part of the National Cancer Institute's (NCI) mission since its creation in 1937. Early on, efforts were limited to international exchange of information to ensure that U.S. cancer patients could benefit from advances in other countries. As NCI's research grant portfolio grew in the 1950s, it included a modest number of grants to foreign institutions, primarily in the U.K. and Europe. In the 1960s, the development of geographic pathology, which aimed to study cancer etiology through variations in cancer incidence and risk factors, led to an increase in NCI funded international research, including research in low- and middle-income countries. In this paper, we review key international research programs, focusing particularly on the first fifty years of NCI history. The first NCI-led overseas research programs, established in the 1960s in Ghana and Uganda, generated influential research but also struggled with logistical challenges and political instability. The 1971 National Cancer Act was followed by the creation of a number of bilateral agreements with foreign governments, including China, Japan, and Russia, to support cooperation in technology and medicine. While these agreements were broad without specific scientific goals, they provided an important mechanism for sustained collaborations in specific areas. With the creation of the NCI Center for Global Health in 2011, NCI's global cancer research efforts gained sustained focus. While the global cancer burden has evolved over time, increasingly impacting low- and middle-income countries, NCI's role in global cancer research remains more important than ever.

A proposed new generation of evidence-based microsimulation models to inform global control of cervical cancer

Health decision models are the only available tools designed to consider the lifetime natural history of human papillomavirus (HPV) infection and pathogenesis of cervical cancer, and the estimated long-term impact of preventive interventions. Yet health decision modeling results are often considered a lesser form of scientific evidence due to the inherent needs to rely on imperfect data and make numerous assumptions and extrapolations regarding complex processes. We propose a new health decision modeling framework that de-emphasizes cytologic-colposcopic-histologic diagnoses due to their subjectivity and lack of reproducibility, relying instead on HPV type and duration of infection as the major determinants of subsequent transition probabilities. We posit that the new model health states (normal, carcinogenic HPV infection, precancer, cancer) and corollary transitions are universal, but that the probabilities of transitioning between states may vary by population. Evidence for this variability in host response to HPV infections can be inferred from HPV prevalence patterns in different regions across the lifespan, and might be linked to different average population levels of immunologic control of HPV infections. By prioritizing direct estimation of model transition probabilities from longitudinal data (and limiting reliance on model-fitting techniques that may propagate error when applied to multiple transitions), we aim to reduce the number of assumptions for greater transparency and reliability. We propose this new microsimulation model for critique and discussion, hoping to contribute to models that maximally inform efficient strategies towards global cervical cancer elimination.

Ensemble Deep Learning for Cervix Image Selection toward Improving Reliability in Automated Cervical Precancer Screening

Automated Visual Examination (AVE) is a deep learning algorithm that aims to improve the effectiveness of cervical precancer screening, particularly in low- and medium-resource regions. It was trained on data from a large longitudinal study conducted by the National Cancer Institute (NCI) and has been shown to accurately identify cervices with early stages of cervical neoplasia for clinical evaluation and treatment. The algorithm processes images of the uterine cervix taken with a digital camera and alerts the user if the woman is a candidate for further evaluation. This requires that the algorithm be presented with images of the cervix, which is the object of interest, of acceptable quality, i.e., in sharp focus, with good illumination, without shadows or other occlusions, and showing the entire squamo-columnar transformation zone. Our prior work has addressed some of these constraints to help discard images that do not meet these criteria. In this work, we present a novel algorithm that determines that the image contains the cervix to a sufficient extent. Non-cervix or other inadequate images could lead to suboptimal or wrong results. Manual removal of such images is labor intensive and time-consuming, particularly in working with large retrospective collections acquired with inadequate quality control. In this work, we present a novel ensemble deep learning method to identify cervix images and non-cervix images in a smartphone-acquired cervical image dataset. The ensemble method combined the assessment of three deep learning architectures, RetinaNet, Deep SVDD, and a customized CNN (Convolutional Neural Network), each using a different strategy to arrive at its decision, i.e., object detection, one-class classification, and binary classification. We examined the performance of each individual architecture and an ensemble of all three architectures. An average accuracy and F-1 score of 91.6% and 0.890, respectively, were achieved on a separate test dataset consisting of more than 30,000 smartphone-captured images.

An Observational Study of Deep Learning and Automated Evaluation of Cervical Images for Cancer Screening

BACKGROUND

Human papillomavirus vaccination and cervical screening are lacking in most lower resource settings, where approximately 80% of more than 500 000 cancer cases occur annually. Visual inspection of the cervix following acetic acid application is practical but not reproducible or accurate. The objective of this study was to develop a "deep learning"-based visual evaluation algorithm that automatically recognizes cervical precancer/cancer.

METHODS

A population-based longitudinal cohort of 9406 women ages 18-94 years in Guanacaste, Costa Rica was followed for 7 years (1993-2000), incorporating multiple cervical screening methods and histopathologic confirmation of precancers. Tumor registry linkage identified cancers up to 18 years. Archived, digitized cervical images from screening, taken with a fixed-focus camera ("cervicography"), were used for training/validation of the deep learning-based algorithm. The resultant image prediction score (0-1) could be categorized to balance sensitivity and specificity for detection of precancer/cancer. All statistical tests were two-sided.

RESULTS

Automated visual evaluation of enrollment cervigrams identified cumulative precancer/cancer cases with greater accuracy (area under the curve [AUC] = 0.91, 95% confidence interval [CI] = 0.89 to 0.93) than original cervigram interpretation (AUC = 0.69, 95% CI = 0.63 to 0.74; P < .001) or conventional cytology (AUC = 0.71, 95% CI = 0.65 to 0.77; P < .001). A single visual screening round restricted to women at the prime screening ages of 25-49 years could identify 127 (55.7%) of 228 precancers (cervical intraepithelial neoplasia 2/cervical intraepithelial neoplasia 3/adenocarcinoma in situ [AIS]) diagnosed cumulatively in the entire adult population (ages 18-94 years) while referring 11.0% for management.

CONCLUSIONS

The results support consideration of automated visual evaluation of cervical images from contemporary digital cameras. If achieved, this might permit dissemination of effective point-of-care cervical screening.

Contemporary Issues in Women's Health

Should we be performing routine salpingectomy as a preventative approach to reduce the risk of ovarian cancer? Machine Learning in Women's Health. Women who undergo cesarean delivery in many parts of Africa are at high risk of severe maternal morbidity and mortality.

T cell receptor repertoire among women who cleared and failed to clear cervical human papillomavirus infection: An exploratory proof-of-principle study

BACKGROUND

It is unknown why a minority of women fail to clear human papillomavirus (HPV) and develop precancer/cancer. Differences in T-cell receptor (TCR) repertoires may identify HPV16-infected women at highest-risk for progression to cancer. We conducted a proof-of-principle study nested within the Guanacaste HPV Natural History Study to evaluate the utility of next-generation sequencing for interrogating the TCR repertoires among women who cleared and failed to clear cervical HPV16.

METHODS

TCR repertoires of women with HPV16-related intraepithelial neoplasia grade 3 or higher (CIN3+; n = 25) were compared to women who cleared an incident HPV16 infection without developing precancer/cancer (n = 25). TCR diversity (richness and evenness) and relative abundance (RA) of gene segment (V [n = 51], D [n = 2], J [n = 13]) usage was evaluated; receiver operating curve analysis assessed the ability to differentiate case-control status.

RESULTS

TCR repertoire richness was associated with CIN3+ status (P = 0.001). Relative abundance (RA) of V-gene segments was enriched for associations between cases and controls. A single V-gene (TRBV6-7) was significantly associated with CIN3+ status (RA = 0.11%, 0.16%, among cases and controls, respectively, Bonferroni P = 0.0008). The estimated area under the curve using richness and V-gene segment RA was 0.83 (95% confidence interval: 0.73-0.90).

CONCLUSIONS

Substantial differences in TCR repertoire among women with CIN3+ compared to women who cleared infection were observed.

IMPACT

This is the first study to use next-generation sequencing to investigate TCR repertoire in the context of HPV infection. These findings suggest that women with HPV16-associated cervical lesions have significantly different TCR repertoires from disease-free women who cleared HPV16 infection.

Cervical cancer incidence after screening with HPV, cytology, and visual methods: 18-Year follow-up of the Guanacaste cohort

Testing negative for human papillomavirus (HPV) predicts long-term reassurance against invasive cervical cancer (ICC). To provide realistic estimates of effectiveness for new screening programs, we studied ICC risk after a 7-year repeated multimethod screening effort. In 1993-1994, 10,049 women aged 18-97 years were enrolled into a population-based cohort study of cervical HPV in Guanacaste, Costa Rica. Women were screened at different intervals according to enrollment results. Each visit (mean 3.2, 90% attendance) included split-sample conventional, automated, and liquid-based cytology, visual inspection, cervicography, and PCR-based HPV testing. Abnormal screening led to colposcopy and excisional treatment as appropriate during the study. Referral to colposcopy for HPV in the absence of other findings was introduced only at the last visit. Population-based Costa Rica Cancer Registry linkage identified cohort women diagnosed with ICC in the 18 years following cohort enrollment. The ICC cumulative risk was 0.4% (n = 38); 18 were diagnosed with ICC after study participation. Of these, 9 were missed at the screening step (negative screening or below the referral threshold, refused screening or colposcopy), 5 attended colposcopy but were not diagnosed as CIN2+, and 4 were treated for CIN2/3 but progressed to ICC nonetheless. Decreasing age-standardized ICC rates for the 1993-2011 period were observed in Guanacaste; cohort women showed additional 31% ICC incidence reduction with apparent downstaging of cancers that occurred. ICC risk following negative HPV testing in the optimal age range 30-50 years was extremely low. Real-life screening effectiveness following introduction is lower than the potential near-complete efficacy predicted by HPV natural history.

Inefficiencies and High-Value Improvements in U.S. Cervical Cancer Screening Practice: A Cost-Effectiveness Analysis

BACKGROUND

Studies suggest that cervical cancer screening practice in the United States is inefficient. The cost and health implications of nonadherence in the screening process compared with recommended guidelines are uncertain.

OBJECTIVE

To estimate the benefits, costs, and cost-effectiveness of current cervical cancer screening practice and assess the value of screening improvements.

DESIGN

Model-based cost-effectiveness analysis.

DATA SOURCES

New Mexico HPV Pap Registry; medical literature.

TARGET POPULATION

Cohort of women eligible for routine screening.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTION

Current cervical cancer screening practice; improved adherence to guidelines-based screening interval, triage testing, diagnostic referrals, and precancer treatment referrals.

OUTCOME MEASURES

Reductions in lifetime cervical cancer risk, quality-adjusted life-years (QALYs), lifetime costs, incremental cost-effectiveness ratios, and incremental net monetary benefits (INMBs).

RESULTS OF BASE-CASE ANALYSIS

Current screening practice was associated with lower health benefit and was not cost-effective relative to guidelines-based strategies. Improvements in the screening process were associated with higher QALYs and small changes in costs. Perfect adherence to screening every 3 years with cytologic testing and adherence to colposcopy/biopsy referrals were associated with the highest INMBs ($759 and $741, respectively, at a willingness-to-pay threshold of $100,000 per QALY gained); together, the INMB increased to $1645.

RESULTS OF SENSITIVITY ANALYSIS

Current screening practice was inefficient in 100% of simulations. The rank ordering of screening improvements according to INMBs was stable over a range of screening inputs and willingness-to-pay thresholds.

LIMITATION

The effect of human papillomavirus vaccination was not considered.

CONCLUSIONS

The added health benefit of improving adherence to guidelines, especially the 3-year interval for cytologic screening and diagnostic follow-up, may justify additional investments in interventions to improve U.S. cervical cancer screening practice.

PRIMARY FUNDING SOURCE

U.S. National Cancer Institute.

HPV16 CpG methyl-haplotypes are associated with cervix precancer and cancer in the Guanacaste natural history study

OBJECTIVE

To evaluate HPV16 CpG methylation and methyl-haplotypes and their association with cervix precancer and cancer utilizing massively parallel single molecule next-generation sequencing (NGS).

METHODS

A nested case-control study of HPV16 positive women was performed in a prospective cohort from Guanacaste, Costa Rica designed to study the natural history of HPV and cervical neoplasia. Controls encompassed 31 women with transient infections; there were 44 cases, including 31 women with CIN3 and 13 with cervical cancer. DNA samples from exfoliated cervical cells were treated with bisulfite and four regions (E6, E2, L2 and L1) were amplified with barcoded primers and tested by NGS. CpG methylation was quantified using a bioinformatics pipeline.

RESULTS

Median methylation levels were significantly different between the CIN3+ cases versus controls in the E2, L2, and L1 regions. Methyl-haplotypes, specifically in 5 CpG sites included in the targeted L2 region, with the pattern "--+-+" had the highest Area Under the Curve value (AUC=88.40%) observed for CIN3 vs.

CONTROLS

The most significant CpG site, L2 4277, determined by bisulfite NGS had an AUC=78.62%.

CONCLUSIONS

This study demonstrates that NGS of bisulfite treated HPV DNA is a useful and efficient technique to survey methylation patterns in HPV16. This procedure provides quantitative information on both individual CpG sites and methyl-haplotypes that identify women with elevated present or subsequent risk for HPV16 CIN3 and cancer.

Evaluation of a low-cost liquid-based Pap test in rural El Salvador: a split-sample study

OBJECTIVE

We sought to test the diagnostic efficacy of a low-cost, liquid-based cervical cytology that could be implemented in low-resource settings.

MATERIALS AND METHODS

A prospective, split-sample Pap study was performed in 595 women attending a cervical cancer screening clinic in rural El Salvador. Collected cervical samples were used to make a conventional Pap (cell sample directly to glass slide), whereas residual material was used to make the liquid-based sample using the ClearPrep method. Selected samples were tested from the residual sample of the liquid-based collection for the presence of high-risk Human papillomaviruses.

RESULTS

Of 595 patients, 570 were interpreted with the same diagnosis between the 2 methods (95.8% agreement). There were comparable numbers of unsatisfactory cases; however, ClearPrep significantly increased detection of low-grade squamous intraepithelial lesions and decreased the diagnoses of atypical squamous cells of undetermined significance. ClearPrep identified an equivalent number of high-grade squamous intraepithelial lesion cases as the conventional Pap. High-risk human papillomavirus was identified in all cases of high-grade squamous intraepithelial lesion, adenocarcinoma in situ, and cancer as well as in 78% of low-grade squamous intraepithelial lesions out of the residual fluid of the ClearPrep vials.

CONCLUSIONS

The low-cost ClearPrep Pap test demonstrated equivalent detection of squamous intraepithelial lesions when compared with the conventional Pap smear and demonstrated the potential for ancillary molecular testing. The test seems a viable option for implementation in low-resource settings.

DNA detection and seroprevalence of human papillomavirus in a cohort of adolescent women

OBJECTIVES

Human papillomavirus (HPV) infections are common in adolescent women, while the rare cancerous sequelae of HPV infections do not generally occur until the 4th or 5th decades of life. This prospective study of a cohort of adolescent women was performed to further our knowledge of the natural history of incident and prevalent HPV infections.

METHODS

Self-vaginal swabs collected from high-risk, unvaccinated adolescent women in a longitudinal study were analysed for HPV DNA. Sera were collected at enrolment and later tested for HPV antibodies. Statistical analysis was performed to determine the HPV genotype distribution and duration of detection, and to determine rates of seropositivity and seroconversion for HPV types represented in the assays.

RESULTS

146 subjects (mean enrolment age=15.4 years; mean duration of follow-up=5.8 years) had samples adequate for analysis of HPV detection, and 95 of these subjects had paired sera available. The cumulative prevalence for high-risk and low-risk HPV types was 95.9% and 91.1%, respectively. HPV types 6, 11, 16 and 18 (HPV types represented in the quadrivalent vaccine) were found at some point in 40.4%, 6.2%, 48% and 24% of participants, respectively. Serological data confirmed exposure to these vaccine-covered types, as well as to other high-risk HPV types.

CONCLUSIONS

In this cohort of adolescent women, high- and low-risk HPV types were frequently detected, and serological data confirmed exposure in most subjects. The high-prevalence HPV types represented in the quadrivalent HPV vaccine further support vaccination of women at an age well before sexual debut.

Precursors in cancer epidemiology: aligning definition and function

A precursor of a disease is a definable pathologic state that progresses directly to disease without a known intermediate step and whose presence substantially increases the likelihood of disease. Precancers, or precursors of cancer, can help provide detail about the dynamic pathogenesis process before clinical disease. Thereby, ascertainment of properly defined precancers can increase precision of estimates and power in epidemiologic and clinical studies. Besides providing targets for direct treatment and improving tools for risk assessment in screening programs, precancers can help establish temporal ordering of cause and effect; can identify relatively homogeneous subsets of cancer that have passed through a given precancer state; and provide a basis for choosing high-risk individuals for detailed longitudinal study. Although the most appropriate definition of the precancer will vary with its function in particular research or clinical applications, the proportion of cancers that progress from the precancer and risk of cancer progressing from the precancer can be important measures of the value of a precancer in translational efforts.

Elevated methylation of HPV16 DNA is associated with the development of high grade cervical intraepithelial neoplasia

We explored the association of human papillomavirus type 16 (HPV16) DNA methylation with age, viral load, viral persistence and risk of incident and prevalent high grade CIN (CIN2+) in serially collected specimens from the Guanacaste, Costa Rica cohort. 273 exfoliated cervical cell specimens (diagnostic and pre-diagnostic) were selected: (1) 92 with HPV16 DNA clearance (controls), (2) 72 with HPV16 DNA persistence (without CIN2+) and (3) 109 with CIN2+. DNA was extracted, bisulfite converted and methylation was quantified using pyrosequencing assays at 66 CpGs across the HPV genome. The Kruskal-Wallis test was used to determine significant differences among groups, and receiver operating characteristic curve analyses were used to evaluate how well methylation identified women with CIN2+. In diagnostic specimens, 88% of CpG sites had significantly higher methylation levels in CIN2+ after correction for multiple tests compared with controls. The highest area under the ROC curve (AUC) was 0.82 for CpG site 6457 in L1, and a diagnostic sensitivity of 91% corresponded to a specificity of 60% for CIN2+. Prospectively, 17% of CpG sites had significantly higher methylation in pre-diagnostic CIN2+ specimens (median time of 3 years before diagnosis) versus controls. The strongest pre-diagnostic CpG site was 6367 in L1 with an AUC of 0.76. Age-stratified analyses suggested that women older than the median age of 28 years have an increased risk of precancer associated with high methylation. Higher methylation in CIN2+ cases was not explained by higher viral load. We conclude that elevated levels of HPV16 DNA methylation may be useful to predict concurrently diagnosed as well as future CIN2+.

Low risk of type-specific carcinogenic HPV re-appearance with subsequent cervical intraepithelial neoplasia grade 2/3

Carcinogenic human papillomavirus (HPV) infections are very common after sexual debut and nearly all become undetectable ("clear") within a few years. Following clearance, the long-term risks of type-specific HPV re-appearance and subsequent risk of cervical intraepithelial neoplasia grade 2 or worse (CIN2+) are not well defined. In the 7-year, population-based cohort study in Guanacaste, Costa Rica, we studied how often type-specific carcinogenic HPV infections re-appeared after clearance and how often re-appearance led to CIN2+. We considered 1,740 carcinogenic HPV infections detected by MY09/11 PCR among 2,805 women (18-91 years old, median 34) who were actively followed at 6- or 12-month intervals. We identified women with one or more type-specific HPV infections that cleared and re-appeared and further defined a subgroup of "definite clearance and re-appearance" (≥2 intervening negative results over a period of ≥1 year). We determined the absolute risk of CIN2+ among the different groups. p values are two-sided. Only 7.7% (81/1,052) of HPV-infected women had intervening negative results. Very few (3.7%, 39/1,052) had "definite clearance and re-appearance", of which 5.1% (2/39) subsequently persisted to a diagnosis of CIN2. There were zero CIN3+ lesions. Extremely few women (2/2,805 of women in our cohort) had a type-specific carcinogenic HPV infection clear, re-appear and lead to CIN2+. If confirmed, this argues against vaccination to avoid re-appearance that leads to precursor lesions and against the need of frequent HPV screening after initial negative results.

Methylation of human papillomavirus type 16 genome and risk of cervical precancer in a Costa Rican population

BACKGROUND

Previous studies have suggested an association between human papillomavirus type 16 (HPV16) genome methylation and cervical intraepithelial neoplasia grade 3 (CIN3) (ie, cervical precancer) and cancer, but the results have been inconsistent.

METHODS

We designed a case-control study within a large prospective cohort of women who underwent multiple screenings for cervical cancer in Guanacaste, Costa Rica. Diagnostic specimens were collected at the time of CIN3 diagnosis (n = 30 case subjects) and persistent HPV16 infection (persistence; n = 35 case subjects), prediagnostic specimens at the first HPV16-positive screening visit (n = 20 CIN3 case subjects; n = 35 persistence case subjects), and control specimens from women with infection clearance within 2 years (n = 34 control subjects). DNA extracted from specimens (cervical cells) was analyzed for methylation levels at 67 CpG sites throughout the HPV16 genome using pyrosequencing. Benjamini-Hochberg method was used to account for multiple testing. Associations between methylation levels and risk of CIN3 or persistence were assessed using logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Increased methylation in diagnostic vs control specimens at nine CpG sites, three in each L1, L2, and E2/E4 genomic regions, was associated with an increased risk of CIN3 (third tertile [high] vs first and second tertiles combined [low], OR = 3.29 [95% CI = 1.16 to 9.34] to 11.12 [95% CI = 2.29 to 76.80]) and persistence. High methylation at three of these CpG sites was associated with a much higher risk when combined compared with low methylation at these sites (OR = 52, 95% CI = 4.0 to 670). In prediagnostic vs control specimens, increased methylation at a CpG site (nucleotide position 4261) in L2 was associated with an increased risk of CIN3.

CONCLUSION

In this HPV16-infected cohort, increased methylation of CpG sites within the HPV16 genome before diagnosis and at the time of diagnosis was associated with cervical precancer.

A large, population-based study of age-related associations between vaginal pH and human papillomavirus infection

Background

Vaginal pH is related to genital tract inflammation and changes in the bacterial flora, both suggested cofactors for persistence of human papillomavirus (HPV) infection. To evaluate the relationship between vaginal pH and HPV, we analyzed data from our large population-based study in Guanacaste, Costa Rica. We examined vaginal pH and the risk of HPV infection, cytological abnormalities, and C. trachomatis infection.

Methods

Our study included 9,165 women aged 18-97 at enrollment with a total of 28,915 visits (mean length of follow-up = 3.4 years). Generalized estimating equations were used to evaluate the relationship between vaginal pH and HPV infection (both overall and single versus multiple types) and low-grade squamous intraepithelial lesions (LSIL), the cytomorphic manifestation of HPV infection. The relationship between enrollment vaginal pH and C. trachomatis infection was assessed by logistic regression. Results were stratified by age at visit.

Results

Detection of HPV was positively associated with vaginal pH, mainly in women < 35 years (p-trend = 0.009 and 0.007 for women aged < 25 and 25-34 years, respectively). Elevated vaginal pH was associated with 30% greater risk of infection with multiple HPV types and with LSIL, predominantly in women younger than 35 and 65+ years of age. Detection of C. trachomatis DNA was associated with increased vaginal pH in women < 25 years (OR 2.2 95% CI 1.0-5.0).

Conclusions

Our findings suggest a possible association of the cervical microenvironment as a modifier of HPV natural history in the development of cervical precancer and cancer. Future research should include studies of vaginal pH in a more complex assessment of hormonal changes and the cervicovaginal microbiome as they relate to the natural history of cervical neoplasia.

Clustering of multiple human papillomavirus infections in women from a population-based study in Guanacaste, Costa Rica

OBJECTIVE

To evaluate clustering patterns of prevalent infection with multiple human papillomavirus (HPV) types in 8365 nonhysterectomized women from the Guanacaste Study of HPV Natural History.

METHODS

HPV testing was performed on cervical cells by MY09/M11 L1 degenerate consensus primer polymerase chain reaction method, with dot-blot hybridization for genotyping. Logistic regression was used to model type-specific HPV positivity, adjusted for age, lifetime number of sexual partners, and specific HPV type prevalence. Woman-level random effects were added to represent unobservable risk factors common to all HPV types.

RESULTS

The observed-to-expected ratio for infections with 2 types was 1.16 (95% credible interval: 1.11-1.21) and for ≥3 types was 1.04 (95% credible interval: .96-1.13). The tendency of HPV types to cluster increased significantly with the genetic similarity of L1 regions. P value < .01 was observed for 2 HPV pairs: HPV-62 and -81 were found together more, while HPV-51 and -71 were found together less often than expected.

CONCLUSIONS

We found a small degree of aggregation between any HPV types and lack of clustering between specific carcinogenic types. Our data indirectly provide reassurance on lack of misclassification for the large majority of HPV types in multiple infections detected by the MY09/11 method and genotyped using dot-blot hybridization.

Long-term risk of recurrent cervical human papillomavirus infection and precancer and cancer following excisional treatment

Risk of recurrent CIN2+ (including cervical intraepithelial neoplasia grade 2 [CIN2], CIN3, carcinoma and in situ, adenocarcinoma in situ or cancer) remains elevated for years following treatment. The role of long-term post-treatment human papillomavirus (HPV) presence on subsequent risk of CIN2+ was evaluated in the 10,049-women Guanacaste cohort. Six hundred eighty-one women were referred to colposcopy because of high-grade cytology, positive cervicography and/or suspicion of cancer based on visual assessment; 486 were judged to require treatment. After excluding women with <12 months of follow-up (N = 88), prior cancer or hysterectomy (N = 37) or other reasons (N = 14), 347 were included in the analysis. Infections were categorized as persistent if present at both pre- and post-treatment visits and new if detected only post-treatment. Median time between the treatment and post-treatment visits was 6.7 years (interquartile range 3.8-7.8). At the post-treatment visit, 8 (2.4%), 2 (0.6%) and 8 (2.4%) of the 347 treated women had persistent HPV16, HPV18 or other carcinogenic HPV, respectively. Two (0.8%), 3 (1.0%) and 13 (4.0%) had new HPV16, HPV18 and other carcinogenic HPV, respectively. Six CIN2+ cases were identified at the post-treatment visit, all with persistent infections (three HPV16, one HPV18 and two other carcinogenic HPV). No recurrent disease was observed among women with new HPV infections during the follow-up period. Thus, persistence of HPV infection a median of six years after treatment was uncommon but, when present, posed a substantial risk of subsequent CIN2+. Serial follow-up data from other studies would further strengthen these conclusions.

Switch from cytology-based to human papillomavirus test-based cervical screening: implications for colposcopy

Human papillomavirus (HPV) testing is more sensitive than cytology; some cervical cancer prevention programs will switch from cytology to carcinogenic HPV test-based screening. The objective of our study is to evaluate the clinical implications of a switch to HPV test-based screening on performance and workload of colposcopy. Women in the population-based, 7-year Guanacaste cohort study were screened at enrollment using cytology. We also took another specimen for HPV DNA testing and collected magnified cervical photographic images (cervigrams). A final case diagnosis (≥cervical intraepithelial neoplasia [CIN] grade 3, CIN2, <CIN2) was assigned at exit. Using the cervigram as a surrogate of colposcopy impression, we evaluated the impact of changing screening method from cytology to carcinogenic HPV testing on the distribution of enrollment colposcopic impression and on the predictive values of positive and negative colposcopic impressions for the cumulative 7-year detection of ≥CIN2 and ≥CIN3. A program based on immediate colposcopic referral after positive HPV would immediately identify as high risk more of the cumulative ≥CIN2 cases than conventional cytology, because of an increased number of referrals. However, the proportion of women that would have visible lesions at referral to colposcopy and the sensitivity versus specificity trade-off of the colposcopic impressions would be similar to programs using cytology (≥ atypical squamous cells of unknown significance [ASCUS]) for referral. The major concern with switching from cytology to more sensitive HPV screening is management of the many HPV-positive women, including those with still nonvisible ≥CIN2 lesions. Our data support the need for a nonvisual diagnostic method to guide management and treatment of HPV-positive women.

Long-term persistence of prevalently detected human papillomavirus infections in the absence of detectable cervical precancer and cancer

BACKGROUND

Detailed descriptions of long-term persistence of human papillomavirus (HPV) in the absence of cervical precancer are lacking.

METHODS

In a large, population-based natural study conducted in Guanacaste, Costa Rica, we studied a subset of 810 initially HPV-positive women with ≥ 3 years of active follow-up with ≥ 3 screening visits who had no future evidence of cervical precancer. Cervical specimens were tested for >40 HPV genotypes using a MY09/11 L1-targeted polymerase chain reaction method.

RESULTS

Seventy-two prevalently-detected HPV infections (5%) in 58 women (7%) persisted until the end of the follow-up period (median duration of follow-up, 7 years) without evidence of cervical precancer. At enrollment, women with long-term persistence were more likely to have multiple prevalently-detected HPV infections (P < .001) than were women who cleared their baseline HPV infections during follow-up. In a logistic regression model, women with long-term persistence were more likely than women who cleared infections to have another newly-detected HPV infection detectable at ≥ 3 visits (odds ratio, 2.6; 95% confidence interval, 1.2-5.6).

CONCLUSIONS

Women with long-term persistence of HPV infection appear to be generally more susceptible to other HPV infections, especially longer-lasting infections, than are women who cleared their HPV infections.

Increased plasma levels of adipokines and inflammatory markers in older women with persistent HPV infection

We observed diminished lymphoproliferation to multiple stimuli in older women with persistent cervical human papillomavirus (HPV) infection. Adipokines are a class of inflammatory cytokines that are altered in some persistent infections. The objective was to compare the level of adipokines and inflammatory cytokines in heparinized plasma from women with persistent HPV cervical infection (Cases, N=50, oversampled for their weak lymphoproliferation responses) with women with no evidence of persistent HPV cervical infection (Controls, N=50, oversampled for their strong lymphoproliferation responses). Plasma samples were analyzed with multiplex assays for adipokines and inflammatory cytokines. Cases had significantly elevated plasma levels of resistin (p<0.0001) and sFas (p=0.0038) as compared to controls. Risk of persistent HPV infection increased significantly with increasing levels of resistin and 8Fas. This is the first study to demonstrate elevated levels of resistin and sFas in HPV persistently infected, older women with decreased immune function expanding the understanding of the systemic inflammation and immune alterations in individuals persistently infected with HPV. Further studies within a larger cohort are needed to define the generalities of these findings and any role adipokines have in persistent HPV infection.

Alterations of T-cell surface markers in older women with persistent human papillomavirus infection

We previously reported decreased lymphocyte proliferative responses among older women with persistent human papillomavirus (HPV) infection. To characterize the phenotype of peripheral lymphocytes associated with persistent HPV infection, we evaluated the expression of different cell surface markers in peripheral blood mononuclear cells (PBMCs) from a case-control study within a 10,049 woman population-based cohort study in Guanacaste, Costa Rica. Women in the cohort aged 46-74 and with HPV results at their 5th year anniversary visit were considered, and all women (n = 87) with persistent HPV infections, all women (n = 196) with transient HPV infections and a random sample of HPV DNA-negative women (n = 261) frequency-matched to cases on age were selected for this study. A median of 3 years after the case-control matching visit, cervical cells were collected for liquid-based cytology and repeat HPV DNA genotyping. Blood was obtained from which PBMCs were extracted and cryopreserved for immunological phenotyping via flow cytometry. Significant increases in risk of HPV persistence were observed for 3 marker subsets indicative of immune cell activation/differentiation. Relative risk estimates were 5.4 (95% CI = 2.2-13.3) for CD69(+)CD4(+), 2.6 (95% CI = 1.2-5.9) for HLADR(+)CD3(+)CD4(+) and 2.3 (95% CI = 1.1-4.7) for CD45RO(+)CD27(-)CD8(+). A significant decrease in HPV persistence was observed for a subset marker indicative of an immature, undifferentiated memory state CD45RO(+)CD27(+)CD4(+) (OR = 0.36; 95% CI = 0.17-0.76). Adjustment for these markers only partially explained the previously reported association between decreased lymphoproliferative responses and persistent HPV infection. Whether phenotypic alterations observed predispose to HPV persistence or result from it should be the focus of future studies.

A unified set of analysis tools for uterine cervix image segmentation

Segmentation is a fundamental component of many medical image-processing applications, and it has long been recognized as a challenging problem. In this paper, we report our research and development efforts on analyzing and extracting clinically meaningful regions from uterine cervix images in a large database created for the study of cervical cancer. In addition to proposing new algorithms, we also focus on developing open source tools which are in synchrony with the research objectives. These efforts have resulted in three Web-accessible tools which address three important and interrelated sub-topics in medical image segmentation, respectively: the Boundary Marking Tool (BMT), Cervigram Segmentation Tool (CST), and Multi-Observer Segmentation Evaluation System (MOSES). The BMT is for manual segmentation, typically to collect "ground truth" image regions from medical experts. The CST is for automatic segmentation, and MOSES is for segmentation evaluation. These tools are designed to be a unified set in which data can be conveniently exchanged. They have value not only for improving the reliability and accuracy of algorithms of uterine cervix image segmentation, but also promoting collaboration between biomedical experts and engineers which are crucial to medical image-processing applications. Although the CST is designed for the unique characteristics of cervigrams, the BMT and MOSES are very general and extensible, and can be easily adapted to other biomedical image collections.

Chlamydia trachomatis and risk of prevalent and incident cervical premalignancy in a population-based cohort

BACKGROUND

Cofactors might affect the risk of the rare progression from infection with carcinogenic human papillomavirus (HPV) to cervical premalignancy to invasive cancer. Some studies have observed that Chlamydia trachomatis infection is associated with increased risk for cervical cancer. In a large prospective cohort, we assessed the role of C trachomatis in cervical premalignancy and addressed confounding by HPV.

METHODS

We identified 182 women with prevalent and 132 women with incident histological cervical intraepithelial neoplasia grade 2 (CIN2), grade 3 (CIN3), or cervical cancer (CIN2+) in the Costa Rica HPV Natural History Study. Control subjects were 995 (approximately 10% of the 10 049) subjects who were randomly selected from the same study. Cervical HPV status at enrollment was determined by MY09/MY11 polymerase chain reaction amplification and dot-blot hybridization. The presence of C trachomatis DNA in cervical exfoliated cells at enrollment was determined by a novel serovar-specific polymerase chain reaction-based C trachomatis detection and genotyping assay. Plasma drawn at enrollment from each subject was used to determine C trachomatis immunoglobulin G (IgG) status. Logistic regression was used to examine the association between C trachomatis and CIN2+, taking into account possible confounding by HPV.

RESULTS

C trachomatis positivity at enrollment was associated with CIN2+ and concurrent and subsequent carcinogenic HPV infection. To account for confounding by HPV status, we restricted the analysis to women positive for carcinogenic HPV DNA at enrollment and found no association between C trachomatis status (as assessed by DNA or IgG) at enrollment and combined prevalent and/or incident CIN2+ (for C trachomatis DNA positivity, odds ratio = 0.77, 95% confidence interval = 0.42 to 1.41; for C trachomatis seropositivity, odds ratio = 1.09, 95% confidence interval = 0.85 to 1.41).

CONCLUSIONS

We found no association between C trachomatis status, as assessed by DNA or IgG, and risk of cervical premalignancy, after controlling for carcinogenic HPV-positive status. Previous positive associations between C trachomatis and cervical premalignancy could have been caused, in part, by an increased susceptibility to HPV infection.

Behavioral/lifestyle and immunologic factors associated with HPV infection among women older than 45 years

BACKGROUND

Cervical human papilloma virus (HPV) detection increases after menopause, but its determinants need clarification.

METHODS

In a case-control study nested within a 10,049 women cohort, we evaluated women 45 to 75 years old who acquired HPV infection and were HPV positive 5 to 6 years after enrollment (N = 252), and HPV-negative women as matched controls (N = 265). Detailed sexual behavior and cellular immune response were investigated. Odds ratios (OR) and attributable fractions were estimated.

RESULTS

Women with 2+ lifetime partners had 1.7-fold (95% CI = 1.1-2.7) higher risk than monogamous women, with similar findings if their partners had other partners. Women with 2+ partners after last HPV-negative result had the highest risk (OR = 3.9; 95% CI = 1.2-12.4 compared with 0-1 partners). Weaker immune response to HPV-16 virus-like particles increased risk (OR = 1.7; 95% CI = 1.1-2.7 comparing lowest to highest tertile). Among women with no sexual activity in the period before HPV appearance, reduced immune response to phytohemagglutinin was the only determinant (OR = 2.9; 95% CI = 0.94-8.8). Twenty-one percent of infections were explained by recent sexual behavior, 21% by past sexual behavior, and 12% by reduced immune response.

CONCLUSIONS

New infections among older women may result from sexual activity of women and/or their partners or reappearance of past (latent) infections possibly related to weakened immune response.

IMPACT

HPV infections among older women are associated with current and past sexual exposures and possibly with immune senescence. The risk of cancer from these infections is likely to be low but could not be fully evaluated in the context of this study.

Elevated systemic levels of inflammatory cytokines in older women with persistent cervical human papillomavirus infection

BACKGROUND

Defects in lymphoproliferative responses to mitogens/antigens in women >45 years old with a persistent type-specific human papillomavirus (HPV) infection have been reported.

METHODS

To determine whether these defects were associated with altered cytokine profiles, plasma and peripheral blood mononuclear cell (PBMC) culture supernatants from 50 cases (oversampled for their reduced lymphoproliferative ability) and 50 uninfected controls (oversampled for their robust lymphoproliferative ability) were examined for 24 cytokines using multiplexed bead-based immunoassays and ELISA.

RESULTS

The following plasma cytokines were significantly increased in cases relative to controls (cases versus controls; median pg/mL): interleukin (IL)-6, 393.1 versus 14.5; IL-8, 1,128.5 versus 43.9; tumor necrosis factor-alpha (TNF-alpha), 164.1 versus 9.2; macrophage inflammatory protein-1alpha (MIP-1alpha), 1,368.9 versus 25.5; granulocyte macrophage colony-stimulating factor (GM-CSF), 13.8 versus 7.3; IL-1beta, 8.3 versus 1.6 (all P < 0.0001); and IL-1alpha, 218.2 versus 169.5 (P = 0.02). We focused our analysis on the cytokines IL-6, IL-8, TNF-alpha, and MIP-1alpha due to their high fold change (>10) and highly statistically significant difference between cases and controls. Length of persistence or type of infection (high risk and low risk) did not affect these differences. IL-6, TNF-alpha, and MIP-1alpha levels were also increased in unstimulated PBMC culture supernatants from cases compared with controls (P < 0.05), however, the cytokine levels from phytohemagglutinin-stimulated PBMC culture supernatants were significantly lower in the cases (P < 0.0001).

CONCLUSIONS

Persistent HPV infection in older women with evidence of immune deficit is associated with an increase in systemic inflammatory cytokines.

IMPACT

Future studies are needed to determine whether the inflammatory profile is age dependent and to examine the role that inflammatory cytokines play in HPV-induced progression from infection to cervical cancer.

A population-based prospective study of carcinogenic human papillomavirus variant lineages, viral persistence, and cervical neoplasia

Human papillomavirus (HPV) types differ profoundly in cervical carcinogenicity. For the most carcinogenic type HPV16, variant lineages representing further evolutionary divergence also differ in cancer risk. Variants of the remaining 10 to 15 carcinogenic HPV types have not been well studied. In the first prospective, population-based study of HPV variants, we explored whether, on average, the oldest evolutionary branches within each carcinogenic type predicted different risks of >2-year viral persistence and/or precancer and cancer [cervical intraepithelial neoplasia grade 3+ (CIN3+)]. We examined the natural history of HPV variants in the 7-year, 10,049-woman Guanacaste Cohort Study, using a nested case-control design. Infections were assigned to a variant lineage determined by phylogenetic parsimony methods based on URR/E6 sequences. We used the Fisher's combination test to evaluate significance of the risk associations, cumulating evidence across types. Globally, for HPV types including HPV16, the P value was 0.01 for persistence and 0.07 for CIN3+. Excluding HPV16, the P values were 0.04 and 0.37, respectively. For HPV16, non-European viral variants were significantly more likely than European variants to cause persistence [odds ratio (OR), 2.6; P = 0.01] and CIN3+ (OR, 2.4; P = 0.004). HPV35 and HPV51 variant lineages also predicted CIN3+. HPV variants generally differ in risk of persistence. For some HPV types, especially HPV16, variant lineages differ in risk of CIN3+. The findings indicate that continued evolution of HPV types has led to even finer genetic discrimination linked to HPV natural history and cervical cancer risk. Larger viral genomic studies are warranted, especially to identify the genetic basis for HPV16's unique carcinogenicity.

Longitudinal study of human papillomavirus persistence and cervical intraepithelial neoplasia grade 2/3: critical role of duration of infection

BACKGROUND

The natural history of human papillomavirus (HPV) infections in older women is critical for preventive strategies, including vaccination and screening intervals, but is poorly understood. In a 7-year population-based cohort study in Guanacaste, Costa Rica, we examined whether women's age and the duration of carcinogenic HPV infections influenced subsequent persistence of infection and risk of cervical intraepithelial neoplasia grade 2 (CIN 2) or worse disease.

METHODS

At enrollment, of the 9466 participants eligible for pelvic examination, 9175 were screened for cervical neoplasia using multiple methods; those with CIN 2 or worse disease were censored and treated. Participants at low risk of CIN 2 or worse (n = 6029) were rescreened at 5-7 years (passively followed), whereas higher-risk participants (n = 2115) and subsets of low-risk women (n = 540) and initially sexually inactive women (n = 410) were rescreened annually or semiannually (actively followed) for up to 7 years. HPV testing was done using a polymerase chain reaction-based method. We determined, by four age groups (18-25, 26-33, 34-41, and > or =42 years), the proportion of prevalent infections (found at baseline) and newly detected infections (first found during follow-up) that persisted at successive 1-year time points and calculated absolute risks of CIN 2 and CIN grade 3 (CIN 3) or worse during follow-up. P values are two-sided.

RESULTS

Regardless of the woman's age, newly detected infections were associated with very low absolute risks of persistence, CIN 2, or worse disease. For newly detected infections, the rate of progression to CIN 2+ (or CIN 3+), after 3 years of follow-up, was not higher for women aged 34 years and older than for younger women. Moreover, rates of newly detected infections declined sharply with age (in the actively followed group, at ages 18-25, 26-33, 34-41, and > or =42 years, rates were 35.9%, 30.6%, 18.1%, and 13.5%, respectively; P < .001). Among prevalent infections, persistent infections among older women (> or =42 years) was higher than that among younger age groups or new infections at any age (P < .01 for comparison of eight groups). Most (66 of 85) CIN 2 or worse detected during follow-up was associated with prevalent infections. Only a small subset (25 of 1128) of prevalent infections persisted throughout follow-up without apparent CIN 2 or worse.

CONCLUSIONS

The rate of new infections declines with age, and new infections typically do not progress to CIN 2 or worse disease in older women; thus, overall potential benefit of prophylactic vaccination or frequent HPV screening to prevent or detect new carcinogenic HPV infections at older ages is low.

Prevalence of human papillomavirus genotypes, and mucosal IgA anti-viral responses in women with cervical ectopy

BACKGROUND

Data on the prevalence of different human papillomavirus (HPV) genotypes and the associated mucosal immune response in women with cervical ectopy are scarce.

OBJECTIVE

To assess the prevalence of different HPV genotypes and the mucosal anti-viral immune response in cervical ectopy.

STUDY DESIGN

Detection and typing of HPV DNA was determined in 141 women with cervical ectopy, 272 cytologically normal controls and 98 low-grade squamous intraepithelial lesions (LSIL) by PCR and direct sequencing. Mucosal IgA antibodies to HPV16 and HPV18 were evaluated in cervical mucus by ELISA.

RESULTS

The prevalence of HPV in cervical ectopy was higher (73.7%) than that observed in control samples (30.5% in endocervix, and 1.8% in exocervix), but similar to the prevalence in LSIL (62.2%). Typing showed that the overall distribution frequency concerned 14 different genotypes, with HPV18 being the most prevalent in cervical ectopy (53.9%), whereas HPV16 predominated in LSIL (38.7%). High-risk HPV genotypes were 2.2 times more frequent in cervical ectopy than in the normal endocervix (p<0.0001). HPV infection in cervical ectopy patients was accompanied by a mucosal IgA-antibody response. Antibody reactivity to HPV18 was significantly higher than the response to HPV16.

CONCLUSION

Cervical ectopy is a risk factor for infection with high-risk HPV genotypes, in particular HPV18. Our results emphasize the need of further studies to clarify the oncogenic potential of this virus in cervical ectopy.

An evaluation by midwives and gynecologists of treatability of cervical lesions by cryotherapy among human papillomavirus-positive women

OBJECTIVES

To estimate efficacy of a visual triage of human papillomavirus (HPV)-positive women to either immediate cryotherapy or referral if not treatable (eg, invasive cancer, large precancers).

METHODS

We evaluated visual triage in the HPV-positive women aged 25 to 55 years from the 10,000-woman Guanacaste Cohort Study (n = 552). Twelve Peruvian midwives and 5 international gynecologists assessed treatability by cryotherapy using digitized high-resolution cervical images taken at enrollment. The reference standard of treatability was determined by 2 lead gynecologists from the entire 7-year follow-up of the women. Women diagnosed with histologic cervical intraepithelial neoplasia grade 2 or worse or 5-year persistence of carcinogenic HPV infection were defined as needing treatment.

RESULTS

Midwives and gynecologists judged 30.8% and 41.2% of women not treatable by cryotherapy, respectively (P < 0.01). Among 149 women needing treatment, midwives and gynecologists correctly identified 57.5% and 63.8% (P = 0.07 for difference) of 71 women judged not treatable by the lead gynecologists and 77.6% and 59.7% (P < 0.01 for difference) of 78 women judged treatable by cryotherapy. The proportion of women judged not treatable by a reviewer varied widely and ranged from 18.6% to 61.1%. Interrater agreement was poor with mean pairwise overall agreement of 71.4% and 66.3% and kappa's of 0.33 and 0.30 for midwives and gynecologists, respectively.

CONCLUSIONS

In future "screen-and-treat" cervical cancer prevention programs using HPV testing and cryotherapy, practitioners will visually triage HPV-positive women. The suboptimal performance of visual triage suggests that screen-and-treat programs using cryotherapy might be insufficient for treating precancerous lesions. Improved, low-technology triage methods and/or improved safe and low-technology treatment options are needed.

Treatability by cryotherapy in a screen-and-treat strategy

OBJECTIVES

We estimated the percentage of women infected with human papillomavirus (HPV+) who cannot be immediately treated with cryotherapy.

MATERIALS AND METHODS

In a 10,000-woman Costa Rican cohort, we analyzed the 559 HPV+ women aged 25 to 55 years and estimated the proportion for whom immediate cryotherapy was not indicated (i.e., invasive cancer, large precancerous lesions, or benign abnormalities that risk failure such as large ectopy, squamocolumnar junction not visualized, polyps, ulcers, or distorted or atrophied cervix). To determine whether cryotherapy at time of baseline HPV screening would effectively treat HPV+ women, 2 expert gynecologists independently judged entire clinical histories (5-7 years of cytology, histology, and HPV tests) and a full longitudinal series of digitized cervical images.

RESULTS

Reviewers judged 144 (25.8%) of 559 HPV+ women as not treatable by immediate cryotherapy. Among 72 women with cervical intraepithelial neoplasia grade 3 who would benefit most from a screening program, 35 (48.6%) were not treatable. In particular, 29 women (40.3%) were determined not treatable for reasons most likely associated with cryotherapy's inadequacy (lesion was large, suspected cancerous or in the endocervical canal or fornix).

CONCLUSIONS

"Screen-and-treat" programs in low-resource settings will soon use a rapid HPV test to screen older women once or twice in their lifetime, identifying women at higher risk for precancer. Our findings suggest that cryotherapy might not effectively treat many precancers, and other safe, low-technology treatment options could be required, in a scenario where all HPV+ women in this targeted group would receive cryotherapy at the same visit.

Neither one-time negative screening tests nor negative colposcopy provides absolute reassurance against cervical cancer

A population sample of 10,049 women living in Guanacaste, Costa Rica, was recruited into a natural history of human papillomavirus (HPV) and cervical neoplasia study in 1993-1994. At the enrollment visit, we applied multiple state-of-the-art cervical cancer screening methods to detect prevalent cervical cancer and to prevent subsequent cervical cancers by the timely detection and treatment of precancerous lesions. Women were screened at enrollment with 3 kinds of cytology (often reviewed by more than one pathologist), visual inspection and cervicography. Any positive screening test led to colposcopic referral and biopsy and/or excisional treatment of CIN2 or worse. We retrospectively tested stored specimens with an early HPV test (hybrid capture tube test) and for >40 HPV genotypes using a research PCR assay. We followed women typically 5-7 years and some up to 11 years. Nonetheless, 16 cases of invasive cervical cancer were diagnosed during follow-up. Six cancer cases were failures at enrollment to detect abnormalities by cytology screening; 3 of the 6 were also negative at enrollment by sensitive HPV DNA testing. Seven cancers represent failures of colposcopy to diagnose cancer or a precancerous lesion in screen-positive women. Finally, 3 cases arose despite attempted excisional treatment of precancerous lesions. Based on this evidence, we suggest that no current secondary cervical cancer prevention technologies applied once in a previously under-screened population is likely to be 100% efficacious in preventing incident diagnoses of invasive cervical cancer.

Short term persistence of human papillomavirus and risk of cervical precancer and cancer: population based cohort study

OBJECTIVE

To evaluate the cumulative incidence of cervical intraepithelial neoplasia II or worse (grade II+) or cervical intraepithelial neoplasia grade III+ after short term persistence of prevalently detected carcinogenic human papillomavirus (HPV).

DESIGN

Population based cohort study.

SETTING

Guanacaste, Costa Rica.

PARTICIPANTS

2282 sexually active women actively followed after enrolment.

MAIN OUTCOME MEASURES

Primary end points: three year and five year cumulative incidence of histologically confirmed cervical intraepithelial neoplasia grade II+ (n=70). Cervical specimens collected at each visit tested for more than 40 HPV genotypes. HPV 16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68, 73, and 82 were considered the primary carcinogenic genotypes.

RESULTS

Women who tested positive for a carcinogenic HPV at enrolment and after about one year (9-21 months) (positive/positive) had a three year cumulative incidence of cervical intraepithelial neoplasia grade II+ of 17.0% (95% confidence interval 12.1% to 22.0%). Those who tested negative/positive (3.4%, 0.1% to 6.8%), positive/negative (1.2%, -0.2% to 2.5%), and negative/negative (0.5%, 0.1% to 0.9%) were at a significantly lower risk. There was little difference in the cumulative incidence of cervical intraepithelial neoplasia grade II+ between testing positive twice for any carcinogenic HPV genotype (same genotype or different genotypes) v testing positive twice for the same carcinogenic genotype (17.0% v 21.3%, respectively). Short term persistence of HPV 16 strongly predicted cervical intraepithelial neoplasia grade II+, with a three year cumulative incidence of 40.8% (26.4% to 55.1%). Similar patterns were observed for the five year cumulative incidence of grade II+ and for three year and five year cumulative incidence of grade III+.

CONCLUSIONS

Short term persistence of a prevalently detected carcinogenic HPV infection, especially HPV 16, strongly predicts a subsequent diagnosis of cervical intraepithelial neoplasia II+ over the next few years.

Human papillomavirus types by age in cervical cancer precursors: predominance of human papillomavirus 16 in young women

In a population-based study conducted in Guanacaste, Costa Rica, we investigated the human papillomavirus (HPV) types detected in 233 cases of cervical intraepithelial neoplasia (CIN) 2/3 and cancer by age. CIN2+ and CIN3+ in young women were significantly more likely to be associated with HPV 16 than the same lesions in older women (80% of CIN3+ were associated with HPV 16 among women ages 18-26 years compared with only 32% among women older than 55 years; Ptrend=0.018). There were no differences by age in HPV 18 positivity. Lesions in older women were mainly caused by other carcinogenic types. This association was present for both prevalent and incident lesions and supports the notion that HPV 16 is a stronger carcinogen than other HPV types. It also has implications for prevention, including the need to vaccinate young women before exposure to HPV vaccine-containing types (HPV 16 and HPV 18) to prevent the majority of cervical cancer precursors.

Human Papillomavirus Quadrivalent Vaccine: A Look Behind The Numbers

The human papillomavirus (HPV) quadrivalent vaocine was licensed in 2006 for prevention of cervical, vulvar, and vaginal cancers caused by HPV-16 and −18 and genital warts caused by HPV-6 and −11. It is also indicated for prevention of precancerous and dysplastic lesions caused by HPV-6, −11, −16, and −18. Questions exist about the number of women and girls infected with the HPV strains covered by the vaccine, as well as about the vaccine's cost-effectiveness. There are also concerns about the efficacy of the vaccine in girls and young women, the population impact of the vaccine, the duration of protection, and the usefulness of the vaccine in developing countries. Careful consideration should be given to these issues by pharmacy and pharmacy professional organizations. To formulate reasonable healthcare guidelines, pharmacists and other healthcare professionals will need to engage policymakers in conversations concerning the vaccine's merits or limitations and the economic impact.

Factors associated with fluctuations in IgA and IgG levels at the cervix during the menstrual cycle

OBJECTIVE

The objective of this analysis was to describe patterns and determinants of cervical immunoglobulin A (IgA) and G (IgG) levels during the menstrual cycle.

METHODS

A total of 154 women who attended 3 visits coinciding with the follicular, periovulatory, and luteal phases of their menstrual cycle were studied. Cervical secretions were collected at each visit for determination of total IgA and IgG levels. Questionnaires administered at each visit inquired about demographic characteristics and behavioral practices.

RESULTS

Total IgA and IgG levels were higher among oral contraceptive (OC) users than among naturally cycling women (hereafter, "non-OC users"). IgA and IgG levels decreased at midcycle, particularly among non-OC users. After adjustment for phase of the current cycle, specimen weight, and detection of blood in the sample, report of a recent illness was associated with lower IgA and IgG levels and increased age with higher IgA and IgG levels among OC users and non-OC users. Increased lifetime number of pregnancies was associated with a higher IgA level among non-OC users and a higher IgG level among OC users. Change in immunoglobulin levels between visits was associated with sample weight and the presence of blood for both OC users and non-OC users.

CONCLUSIONS

Phase of the current menstrual cycle and OC use were significant determinants of cervical IgA and IgG levels. The impacts of endogenous and exogenous hormones on cervical immunoglobulin levels should be further investigated.

Rationale and design of a community-based double-blind randomized clinical trial of an HPV 16 and 18 vaccine in Guanacaste, Costa Rica

We report the rationale, design, methods and details of participation of a community-based, double-blind, randomized clinical trial of an HPV 16 and 18 vaccine conducted in two provinces of Costa Rica to investigate the efficacy and population impact of the vaccine in the prevention of cervical cancer precursors. More than 24,000 women between 18 and 25 years of age were invited to participate and pre-screened for eligibility, with recruitment of 7466 women (30% of those pre-screened, 59% of those eligible) who were randomized to receive 3 doses of the HPV vaccine or hepatitis A vaccine as control. A complex protocol of data and specimen collection was applied, including an interview, pelvic exam for sexually active women, blood for serology and cell-mediated immunity, cervical secretions for local immunity and cells for HPV, Chlamydia trachomatis and gonorrhea testing. Eighty percent of the women received three doses, 12.4% two doses and 7.4% one dose. At visits, compliance with data and specimen collection was close to 100%. Baseline characteristics and age-specific prevalence of HPV and cervical neoplasia are reported. Overall prevalence of HPV was high (50%), with 8.3% of women having HPV 16 and 3.2% HPV 18. LSIL was detected in 12.7% of women at baseline and HSIL in 1.9%. Prevalence of Chlamydia was 14.2%. There was very good agreement in HPV detection between clinician-collected and self- collected specimens (89.4% agreement for all types, kappa 0.59). Follow up will continue with yearly or more frequent examinations for at least 4 years for each participant.

Rapid clearance of human papillomavirus and implications for clinical focus on persistent infections

Health professionals and the public need to understand the natural history of human papillomavirus (HPV) infections of the cervix to best use the information provided by new molecular screening tests. We investigated outcomes of 800 carcinogenic HPV infections detected in 599 women at enrollment into a population-based cohort (Guanacaste, Costa Rica). For individual infections, we calculated cumulative proportions of three outcomes (viral clearance, persistence without cervical intraepithelial neoplasia grade 2 or worse [CIN2+], or persistence with new diagnosis of CIN2+) at successive 6-month time points for the first 30 months of follow-up. Cervical specimens were tested for carcinogenic HPV genotypes using an L1 degenerate-primer polymerase chain reaction method. Infections typically cleared rapidly, with 67% (95% confidence interval [CI] = 63% to 70%) clearing by 12 months. However, among infections that persisted at least 12 months, the risk of CIN2+ diagnosis by 30 months was 21% (95% CI = 15% to 28%). The risk of CIN2+ diagnosis was highest among women younger than 30 years with HPV-16 infections that persisted for at least 12 months (53%; 95% CI = 29% to 76%). These findings suggest that the medical community should emphasize persistence of cervical HPV infection, not single-time detection of HPV, in management strategies and health messages.

A comparison of cervical and vaginal human papillomavirus

OBJECTIVES

We wanted to compare detection of a broad spectrum of human papillomavirus (HPV) types detected in cellular specimens from the vagina and cervix, which could provide information about the potential of each anatomical site for harboring infection. Previous studies have failed to present data on or detect a broad spectrum of HPV genotypes and/or have not carefully sampled the vagina, instead relying on self-collection that is likely contaminated with cervical cells.

STUDY DESIGN

We conducted follow-up study of 353 women who had participated in study of HPV and cervical neoplasia in Costa Rica. We collected paired cervical and vaginal specimens; vaginal specimens were collected from the fornix to minimize cervical contamination. Specimens were tested in a masked fashion for >40 HPV types using a MY09/MY11 PCR method and type-specific dot blot hybridization.

RESULTS

The prevalence for any carcinogenic HPV type in vaginal and cervical specimens was similar (P = 0.3). However, the prevalence for any HPV type in vaginal specimens was greater than in cervical specimens (P = 0.0002), primarily due to a twofold increased vaginal prevalence of HPV types of the alpha3/alpha15 phylogenetic species (e.g., HPV61) (P <0.00005).

CONCLUSIONS

Carcinogenic HPV types appeared to have a similar affinity for vaginal and cervical epithelium, but noncarcinogenic HPV types of the alpha3/alpha15 phylogenetic species may have a tropism for vaginal epithelium.

High load for most high risk human papillomavirus genotypes is associated with prevalent cervical cancer precursors but only HPV16 load predicts the development of incident disease

Cervicovaginal human papillomavirus (HPV) viral load has been purported as a potential marker for the detection of high-grade cervical intraepithelial neoplasia or cancer (>/=CIN2). To examine disease association with type-specific viral load for the full-range of anogenital HPV infections, we conducted cross-sectional and prospective analyses of approximately 2,000 HPV-infected women from a 10,000-woman population-based study in Guanacaste, Costa Rica with 7 years of follow-up. Cervical specimens were tested for >40 HPV types using a MY09/MY11 L1 consensus primer PCR method with type-specific dot blot hybridization and PCR signal intensity as a measure of viral load. A positive association was observed between prevalent >/=CIN2 and high viral load compared to low viral load for women with baseline single HPV16 infections (OR = 19.2, 95% CI = 4.4-83.2) and single non-16 carcinogenic infections (OR = 9.2, 95% CI = 2.1-39.9). Inclusion of women with multiple HPV types did not substantially change these associations. In prospective follow-up, only women infected with HPV16 alone (OR = 27.2, 95% = 3.5-213.5) had a strong association between high viral load and incident >/=CIN2; non-16 carcinogenic high viral load was not associated with incident >/=CIN2 (OR = 0.7, 95% CI = 0.2-1.9). Single noncarcinogenic type viral load was not associated with increased risk of prevalent or incident >/=CIN2 (OR = 1.2 and 1.1, respectively). In conclusion, carcinogenic high viral load was associated with prevalent >/=CIN2; however HPV16 was uniquely associated with incident >/=CIN2. The extent to which these observations can be translated into clinical practice must be rigorously examined in the context of the method of viral load measurement and the type-specific differences observed for incident >/=CIN2.

Evaluation of two types of sponges used to collect cervical secretions and assessment of antibody extraction protocols for recovery of neutralizing anti-human papillomavirus type 16 antibodies

Immunogenicity evaluations in human papillomavirus (HPV) vaccine trials have relied on serological samples, yet cervical antibodies are likely to be most relevant for protection against infection. In order to assess functional antibody levels at the cervix, the secreted-alkaline-phosphatase neutralization assay (SEAPNA) was used to measure HPV-neutralizing activity. We assessed the variability of the SEAPNA with serum samples after vaccination with an HPV type 16 (HPV16) L1 virus-like particle vaccine and whether the SEAPNA can be used to monitor neutralizing activity at the cervix. The SEAPNA has an overall coefficient of variation of 29.3%. Recovery from ophthalmic sponges was assessed by spiking V5 (mouse anti-HPV16) antibody onto and extracting it from sterile Merocel and Ultracell sponges and sponges used to collect specimens from participants. V5 recovery from sterile Merocel sponges was complete, yet that from Ultracell sponges was null. The mean V5 recoveries from participant Ultracell and Merocel sponges were 61.2% and 93.5%, respectively, suggesting that Merocel sponges are more appropriate for specimen collection. The SEAPNA can be applied to determine the surrogates of protection and to examine the durability of protection at the cervix.

CIN2 Is a Much Less Reproducible and Less Valid Diagnosis than CIN3

We wished to compare the relative reproducibility and validity of cervical intraepithelial neoplasia (CIN) 2 and CIN3 diagnoses. In a population-based cohort study (1993-2001) of human papillomavirus (HPV) and cervical neoplasia in Costa Rica, we compared community pathologists' diagnoses with those of the 2 independent reviewers from the United States (total, n = 357). As measures of validity, we correlated primary and review diagnoses with HPV positivity and cytological interpretations. Two review pathologists agreed with 84% and 81%, respectively, of initial diagnoses of CIN3 compared with 13% and 31% of CIN2. The CIN3 diagnoses made by review pathologists were 94% oncogenic HPV positive, compared with 72% of CIN2 diagnoses. Eighty-one percent of CIN3 diagnoses versus 61% of CIN2 were correlated with high-grade cytological interpretations. The CIN3 is a substantially more reproducible diagnosis that can be validated more frequently with HPV tests and cytological interpretations than CIN2.

Human papillomavirus genotyping after denaturation of specimens for Hybrid Capture 2 testing: feasibility study for the HPV persistence and progression cohort

Human papillomavirus (HPV) genotyping could be clinically useful, depending on the results of large, prospective studies like the HPV persistence and progression (PaP) cohort. The cohort is based on genotyping and follow-up of Hybrid Capture-positive women at Kaiser Permanente, Northern California. HPV DNA testing by Hybrid Capture 2 requires denaturation with alkali, possibly damaging the DNA for optimal PCR-based genotyping. A feasibility study was conducted on paired aliquots of anonymized specimens from 100 women with low-grade intraepithelial lesion cytology. Test aliquots were left in denaturant for 10 or 18h at 4 degrees C and then neutralized; comparison aliquots were not denatured but diluted to match the timing, temperature, concentration and salt conditions of the treated specimens. The masked aliquots were tested using a commercialized PCR-based assay that detects of 37 HPV genotypes. There was no overall effect of treatment on test positivity or number of types. HPV16 was marginally more likely to be detected in untreated versus treated aliquots (P=0.09) but HPV45 was marginally more likely to be detected in treated than untreated aliquots (P=0.07), suggesting that these differences represented chance (intra-test variability). It can be concluded that residual Hybrid Capture-positive specimens can be genotyped by PCR after Hybrid Capture 2 processing.

The Natural History of Human Papillomavirus Infection and Cervical Intraepithelial Neoplasia Among Young Women in the Guanacaste Cohort Shortly After Initiation of Sexual Life

OBJECTIVE

Cross-sectional analyses of our 10,000-woman, population-based Guanacaste cohort suggest a lag of > or =10 years between the peak of human papillomavirus (HPV) infection and the later peak of cervical intraepithelial neoplasia grade 3 (CIN 3). We wanted to explore early HPV natural history and CIN 3 prospectively.

STUDY DESIGN

As part of the Guanacaste cohort, we followed 206 initially virginal women aged 18 to 26 semiannually for a median of 3.6 years after initiation of sexual life.

RESULTS

A total of 53.4% of women tested positive during the study for > or =1 HPV type. Very few infections persisted for >1 to 2 years. Three women had histologically confirmed CIN 3, of which 2 showed persistent HPV 16. The other had serologic evidence of HPV 31.

CONCLUSIONS

HPV infection occurs frequently and clears rapidly in most young women initiating sexual intercourse. Persistent HPV 16 can cause early CIN 3. The peak age for CIN 3 will decline with the increased screening intensity and sensitivity typical of longitudinal studies.

Prophylaktische und therapeutische HPV-Impfstoffe

Papilloma viruses (PV) have been known to cause benign and malignant tumors in animals for more than 100 years. It took over 20 years to win general acceptance for their causative role in anogenital carcinomas in humans in particular in cervial carcinoma. Extensive research has led to the development of a prophylactic vaccine which is now commercially available. It remains to be investigated if HPV-specific therapeutic vaccines can be developed.

Persistent human papillomavirus infection is associated with a generalized decrease in immune responsiveness in older women

The development of cervical cancer and its precursors are linked to persistent infection with oncogenic types of human papillomavirus (HPV). Host immune responses seem to be determinants of risk for this disease. However, little is known about the immunologic determinants of HPV persistence. Here, we examined the association between lymphoproliferative responses to antigens/mitogens and persistent HPV infection in women older than 45 years. Women included in this study were participants in a 10,000-woman population-based cohort study of cervical neoplasia in Costa Rica. Women older than 45 years and HPV DNA positive at a screening visit were selected as cases (n = 283). We selected a comparably sized control group of HPV DNA-negative women, matched to cases on age and time since enrollment (n = 261). At an additional clinical visit, women were cytologically and virologically rescreened, and cervical and blood specimens were collected. Proliferative responses to phytohemagglutinin (PHA), influenza virus (Flu), and HPV16 virus-like particle (VLP) were lower among women with persistent HPV infection [median counts per minute (cpm): 72,849 for PHA, 1,241 for Flu, and 727 for VLP] than for the control group (median cpm: 107,049 for PHA, 2,111 for Flu, and 2,068 for VLP). The decreases were most profound in women with long-term persistence and were only observed for the oldest age group (>/=65 years). Our results indicate that an impairment in host immunologic responses is associated to persistent HPV infection. The fact that effects were evident for all studied stimuli is suggestive of a generalized effect.