Diagnosis and management of oncogenic cervical human papillomavirus infection

Association between oral contraceptives and cervical cancer: A retrospective case-control study based on the National Health and Nutrition Examination Survey

Background: Cervical cancer is the fourth most common cancer among females globally, with a high incidence and high mortality among females in developing countries. This retrospective case-control study aimed to investigate the association between oral contraceptives and cervical cancer, on which insufficient evidence still exists. Material and Methods: To examine the association between oral contraceptives and cervical cancer based on 7,496 females aged over 20 years from the National Health and Nutrition Examination Survey, multivariable logistic regression conducted from 1999 to 2016 was used. Results: Contraceptive use was positively associated with cervical cancer risk. In model 1 (unadjusted), a 195% increased risk of cervical cancer was observed among those who used oral contraceptives (odds ratio [OR] = 2.27, 95% confidence interval [CI] = 1.39-3.98, p = 0.002) compared to those who did not. In addition, the ORs for the exposed population were 1.74 (95% CI = 1.05-3.08, p = 0.041) and 1.93 (95% CI = 1.16-3.44, p = 0.017) in model 2 (adjusted for age, race, and body mass index [BMI]) and model 3 (adjusted for education level, ratio of family income to poverty, drinking status, smoking status, number of pregnancies, age at first sex, number of sexual partners, and whether to receive the human papillomavirus (HPV) vaccine in addition to model 2), respectively. Furthermore, subgroup analyses stratified by age, smoking status, BMI, age at first sex, number of sexual partners, and whether to receive the HPV vaccine also revealed that oral contraceptives were significantly associated with cervical cancer. Conclusion: This study demonstrated that oral contraceptive use increased the risk of cervical cancer. In addition, the higher risk, including individuals older than 45 years, having a high BMI (≥30 kg/m2), being current smokers, and having more than five sexual partners, may contribute to the development of cervical cancer.

Advancements in electrochemical DNA sensor for detection of human papilloma virus - A review

Human papillomavirus (HPV) is one of the most common sexually transmitted disease, transmitted through intimate skin contact or mucosal membrane. The HPV virus consists of a double-stranded circular DNA and the role of HPV virus in cervical cancer has been studied extensively. Thus it is critical to develop rapid identification method for early detection of the virus. A portable biosensing device could give rapid and reliable results for the identification and quantitative determination of the virus. The fabrication of electrochemical biosensors is one of the current techniques utilized to achieve this aim. In such electrochemical biosensors, a single-strand DNA is immobilized onto an electrically conducting surface and the changes in electrical parameters due to the hybridization on the electrode surface are measured. This review covers the recent developments in electrochemical DNA biosensors for the detection of HPV virus. Due to the several advantages of electrochemical DNA biosensors, their applications have witnessed an increased interest and research focus nowadays.

Modelling the effects of quadrivalent Human Papillomavirus (HPV) vaccination in Puerto Rico

Background

No study has estimated the potential impact of Human Papillomavirus (HPV) vaccination in Puerto Rico, a population with considerable burden of HPV-related morbidities. We evaluated the health and economic impacts of implementing a vaccination strategy for females and males in Puerto Rico, with the quadrivalent HPV (HPV4) vaccine, under different vaccination scenarios.

Methods

We adapted a mathematical model which estimates the direct and indirect health benefits and costs of HPV4 vaccination in a dynamic population. The model compared three vaccination scenarios against screening only (no-vaccination) for three doses of HPV4 vaccine among individuals aged 11–15 years in Puerto Rico: 1) 34% for females and 13% for males (34%F/13%M), 2) 50% for females and 40% for males (50%F/40%M), and 3) 80% for female and 64% for male (80%F/64%M). Data specific to Puerto Rico was used. When not available, values from the United States were used. Input data consisted of demographic, behavioral, epidemiological, screening, and economic parameters.

Results

The model predicted decreases in: 1) HPV infection prevalence for females and males, 2) cervical intraepithelial neoplasia and cervical cancer incidence for females, 3) genital warts incidence for females and males, and 4) cervical cancer deaths among females, when various vaccination program scenarios were considered. In addition, when the vaccination percentage was increased in every scenario, the reduction was greater and began earlier. The analysis also evidenced an incremental cost effectiveness ratio (ICER) of $1,964 per quality–adjusted life year gained for the 80%F/64%M uptake scenario.

Conclusions

HPV vaccine can prove its cost effectiveness and substantially reduce the burden and costs associated to various HPV-related conditions when targeted to the adequate population together with an organized HPV vaccination program.

Multiplex Paper-Based Colorimetric DNA Sensor Using Pyrrolidinyl Peptide Nucleic Acid-Induced AgNPs Aggregation for Detecting MERS-CoV, MTB, and HPV Oligonucleotides

The development of simple fluorescent and colorimetric assays that enable point-of-care DNA and RNA detection has been a topic of significant research because of the utility of such assays in resource limited settings. The most common motifs utilize hybridization to a complementary detection strand coupled with a sensitive reporter molecule. Here, a paper-based colorimetric assay for DNA detection based on pyrrolidinyl peptide nucleic acid (acpcPNA)-induced nanoparticle aggregation is reported as an alternative to traditional colorimetric approaches. PNA probes are an attractive alternative to DNA and RNA probes because they are chemically and biologically stable, easily synthesized, and hybridize efficiently with the complementary DNA strands. The acpcPNA probe contains a single positive charge from the lysine at C-terminus and causes aggregation of citrate anion-stabilized silver nanoparticles (AgNPs) in the absence of complementary DNA. In the presence of target DNA, formation of the anionic DNA-acpcPNA duplex results in dispersion of the AgNPs as a result of electrostatic repulsion, giving rise to a detectable color change. Factors affecting the sensitivity and selectivity of this assay were investigated, including ionic strength, AgNP concentration, PNA concentration, and DNA strand mismatches. The method was used for screening of synthetic Middle East respiratory syndrome coronavirus (MERS-CoV), Mycobacterium tuberculosis (MTB), and human papillomavirus (HPV) DNA based on a colorimetric paper-based analytical device developed using the aforementioned principle. The oligonucleotide targets were detected by measuring the color change of AgNPs, giving detection limits of 1.53 (MERS-CoV), 1.27 (MTB), and 1.03 nM (HPV). The acpcPNA probe exhibited high selectivity for the complementary oligonucleotides over single-base-mismatch, two-base-mismatch, and noncomplementary DNA targets. The proposed paper-based colorimetric DNA sensor has potential to be an alternative approach for simple, rapid, sensitive, and selective DNA detection.

A highly sensitive quantum dots-DNA nanobiosensor based on fluorescence resonance energy transfer for rapid detection of nanomolar amounts of human papillomavirus 18

A very sensitive and convenient nanobiosensor based on fluorescence resonance energy transfer (FRET) was developed for the detection of a 22-mer oligonucleotides sequence in Human Papillomavirus 18 virus (HPV18) gene. For this purpose, water-soluble CdTe quantum dots (QDs) were synthesized and, subsequently, amino-modified 11-mer oligonucleotide as one of the two necessary probes was attached to QDs surface to form functional QDs-DNA conjugates. Right after addition of the QDs-DNA and a second Cyanine5 (Cy5)-labeled 11-mer oligonucleotide probe to the DNA target solution, the sandwiched hybrids were formed. The resulting hybridization brings the Cy5 fluorophore as the acceptor to close proximity of the QDs as donor, so that an effective transfer of energy from the excited QDs to the Cy5 probe would occur via FRET processing. The fluorescence intensity of Cy5 found to linearly enhance by increasing the DNA target concentration from 1.0 to 50.0nM, with a detection limit of 0.2nM. This homogeneous DNA detection method does not require excessive washing and separation steps of un-hybridized DNA, due to the fact that no FRET can be observed when the probes are not ligated. Finally, feasibility and selectivity of the proposed one-spot DNA detection nanobiosensor were investigated by analysis of derived nucleotides from HPV18 and mismatched sequences.

CHAPTER 7 Methods for detection of HPV infection and its clinical utility

HPVs cannot be cultured and the detection of virus relies on a variety of techniques used in immunology, serology, and molecular biology. Currently the only FDA-approved commercially available method for the detection of HPV DNA is the Hybrid Capture assay, version hc2 (Digene, Gaithersburg, MD, USA) which is able to detect 13 high-risk types of HPV. The advantage of PCR-based methods of HPV DNA detection is that they allow for the identification of different types of HPV. This article discusses the advantages and disadvantages of the different methods of HPV DNA detection. HPV DNA testing can be used in a variety of clinical scenarios that include a primary screening test, particularly in women older than 30 years;as an adjunctive test to cytology;to triage women who have an equivocal cytologic finding, e.g., ASC-US, or for follow up post-treatment. In addition, HPV DNA testing can be performed on samples obtained by women themselves (so-called self-sampling), which may be useful in women who are resistant to undergoing gynecologic examinations.

Application of multiplex PCR for Rapid and sensitive detection of human papillomaviruses in cervical cancer

Objectives:

Reffering to an increase in cervical cancer in the recent years, rapid, sensitive and economical detection of human papillomaviruses (HPVs) as causative agents of cervical cancer is important. The traditional methods for the detection of HPVs in cervical cancer, such as pap smear, suffer from limitation and PCR has a potential to overcome the limitaitons. The purpose of present research work was to identify the five important strains of HPV (16, 18, 31, 33 and 45) simultaneously by Multiplex PCR application.

Methods:

Study was done on 100 cervical lesions of women. DNA was extracted from specimens by a genomic DNA purification kit. A 5-plex PCR was developed for the simultaneous detection of major HPV. Five pair of new primers was designed for detection of HPV 16, 18, 31, 33 and 45 by Multiplex PCR.

Results:

Among the 100 evaluated samples, 82 were found positive to HPVs. In the meantime the highest rate of infection was for HPV 16. Also 30 of HPV positive samples had infections with two or more HPV types.

Conclusion:

Multiplex PCR assay used in present study can provide a rapid, sensitive and economical method for detection of viral infections and is applicable to small volumes of vaginal samples.

Modern therapy of anogenital warts

Modern views on human papilloma virus are presented. Actual approaches to diagnostics and treatment of patients with anogenital warts are discussed. Clinical cases of high efficiency of Imiquimodum (Keravort) in treating anogenital warts of men and women are illustrated.

Detection of human papillomavirus (HPV) DNA prevalence and p53 codon 72 (Arg72Pro) polymorphism in prostate cancer in a Greek group of patients

Prostate cancer is the most common neoplasm found in males and the second most frequent cause of cancer-related mortality in males in Greece. Among other pathogens, the detection frequency of human papillomavirus (HPV) has been found to be significantly increased in tumor tissues among patients with sexually transmitted diseases (STDs), depending on the geographical distribution of each population studied. The present study focused on the detection of HPV and the distribution of Arg72Pro p53 polymorphism in a cohort of healthy individuals, as well as prostate cancer patients. We investigated the presence of HPV in 50 paraffin-embedded prostate cancer tissues, as well as in 30 physiological tissue samples from healthy individuals by real-time PCR. Furthermore, the same group of patients was also screened for the presence of the Arg72Pro polymorphism of the p53 gene, a p53 polymorphism related to HPV. Out of the 30 control samples, only 1 was found positive for HPV (3.33 %). On the contrary, HPV DNA was detected in 8 out of the total 50 samples (16 %) in the prostate cancer samples. The distribution of the three genotypes, Arg/Arg, Arg/Pro, and Pro/Pro, was 69.6, 21.7, and 8.7 % in the cancer patients and 75.0, 17.86, and 7.14 % in healthy controls, respectively. No statistically significant association was observed between the HPV presence and the age, stage, p53 polymorphism status at codon 72, or PSA. The increased prevalence of HPV detected in the prostate cancer tissues is in agreement with that reported in previous studies, further supporting the association of HPV infection and prostate cancer.

Electrochemical detection of human papillomavirus DNA type 16 using a pyrrolidinyl peptide nucleic acid probe immobilized on screen-printed carbon electrodes

An electrochemical biosensor based on an immobilized anthraquinone-labeled pyrrolidinyl peptide nucleic acid (acpcPNA) probe was successfully developed for the selective detection of human papillomavirus (HPV) type 16 DNA. A 14-mer acpcPNA capture probe was designed to recognize a specific 14 nucleotide region of HPV type 16 L1 gene. The redox-active label anthraquinone (AQ) was covalently attached to the N-terminus of the acpcPNA probe through an amide bond. The probe was immobilized onto a chitosan-modified disposable screen-printed carbon electrode via a C-terminal lysine residue using glutaraldehyde as a cross-linking agent. Hybridization with the target DNA was studied by measuring the electrochemical signal response of the AQ label using square-wave voltammetric analysis. The calibration curve exhibited a linear range between 0.02 and 12.0 µM with a limit of detection and limit of quantitation of 4 and 14 nM, respectively. This DNA sensing platform was successfully applied to detect the HPV type 16 DNA from a PCR amplified (240 bp fragment of the L1 gene) sample derived from the HPV type 16 positive human cancer cell line (SiHa), and failed to detect the HPV-negative c33a cell line. The sensor probe exhibited very high selectivity for the complementary 14 base oligonucleotide over the non-complementary oligonucleotides with sequences derived from HPV types 18, 31 and 33. The proposed sensor provides an inexpensive tool for the early stage detection of HPV type 16, which is an important biomarker for cervical cancer.

Detection and typing of human papilloma virus by multiplex PCR with type-specific primers

The primary underlying cause of cervical cancer is infection with one or more high-risk (HR) types of the human papilloma virus (HPV). Detection and typing of HPV have been commonly carried out by PCR-based assays, where HPV detection and typing are two separate procedures. Here, we present a multiplex PCR-based HPV typing assay that detects 20 HPV types (15 HR, 3 probably HR and 2 low risk) using type-specific primers and agarose gel electrophoresis. 46 cervical, urethral, and biopsy samples were analyzed by both Multiplex PCR and PGMY09/11 consensus PCR, and results were compared. 611 samples were further analyzed by Multiplex PCR, 282 were positive for HR HPV, and 101 showed multiple HR HPV infections. The relatively ease and economic accessibility of the method and its improved ability to detect high-risk HPV types in multiple HPV-infected samples make it an attractive option for HPV testing.

Deconstructing fatalism: ethnographic perspectives on women's decision making about cancer prevention and treatment

Researchers have long held that fatalism (the belief in a lack of personal power or control over destiny or fate) constitutes a major barrier to participation in positive health behaviors and, subsequently, adversely affects health outcomes. In this article, we present two in-depth, ethnographic studies of rural women's health decisions surrounding cancer treatments to illustrate the complexity and contestability of the long-established fatalism construct. Narrative analyses suggest that for these women, numerous and complex factors--including inadequate access to health services, a legacy of self-reliance, insufficient privacy, combined with a culturally acceptable idiom of fatalism--foster the use of, but not necessarily a rigid conviction in, the notion of fatalism.

Perspectives on Pap test follow-up care among rural Appalachian women

Approximately one- to three-quarters of women notified of abnormal Pap test results do not receive appropriate follow-up care, dramatically elevating their risk for invasive cervical cancer. We explored barriers to and facilitators of follow-up care for women in two counties in Appalachian Kentucky, where invasive cervical cancer incidence and mortality are significantly higher than the national average. In-depth interviews were conducted among 27 Appalachian women and seven local health department personnel. Those who had been told of an atypical Pap test result tended to have one of three reactions: (1) not alarmed and generally did not obtain follow-up care; (2) alarmed and obtained follow-up care; or (3) alarmed, but did not obtain care. Each of these typologies appeared to be shaped by a differing set of three categories of influences: personal factors; procedure/provider/system factors; and ecological/community factors. Recommendations to increase appropriate follow-up care included pursuing research on explanations for these typologies and developing tailored interventions specific to women in each of the response types.

Human papilloma virus genotyping, variants and viral load in tumors, squamous intraepithelial lesions, and controls in a north Indian population subset

A study of human papilloma virus (HPV) types and variants is important for developing preventive protocols and appropriate intervention targets. The presence of HPV types, their variants, and viral load in a population subset from North India was studied. Polymerase chain reaction (PCR) and line blots were used for HPV genotyping; HPV 16 and 18 viral loads were measured using real-time PCR. Variant analysis was done by sequencing of the PCR-amplified E6/E7 regions of HPV 16 and the long control region and E6/E7 regions of HPV 18. The 93.6%, 78.6%, and 10% of tumors, squamous intraepithelial lesions (SILs), and controls were HPV-positive, respectively. The most commonly observed type was HPV 16. Human papilloma virus 73 which is uncommonly observed was seen in 2 tumors. Multiple infections were more common in controls and SILs than tumors. The majority (86.4%) of the HPV 16-positive and all of the HPV 18-positive samples belonged to the European variant class. Five novel nonsynonymous changes were seen in the HPV 16-positive and 2 in HPV 18-positive samples. There was a significant increase in viral loads from controls through SILs to tumors, but no significant differences in viral loads were observed between different stages of cancer. In tumors, a significant increase in HPV 16 viral loads was seen with increasing age. The study shows a similar HPV type and variant distribution to European studies, with some differences in type distribution. Viral load does not appear to be good marker for stage wise progression and intralesional variability may affect its use as a differentiating parameter between high-grade squamous intraepithelial lesion and low-grade squamous intraepithelial lesions.

Development and evaluation of a liquid bead microarray assay for genotyping genital human papillomaviruses

We developed a liquid bead microarray (LBMA) assay for genotyping genital human papillomaviruses (HPVs) based on the MY09-MY11-HMB01 PCR system and the reverse line blot (RLB) assay probe sequences. Using individual HPV plasmids, we were able to detect as few as 50 copies per reaction. In two separate retrospective studies, the LBMA assay was compared to the RLB assay and to the Hybrid Capture II (hc2) assay. Testing was performed without knowledge of other assay results. In the first study, 614 cervical swab samples (enriched for HPV infection) from 160 young women were tested for HPV DNA, and 360 (74.8%) type-specific HPV infections were detected by both assays, 71 (14.8%) by the LBMA assay only, and 50 (10.4%) by the RLB assay only. Type-specific agreement for the two assays was excellent (99.1%; kappa=0.85; 95% confidence interval [95% CI], 0.82 to 0.88). Samples with discrepant LBMA and RLB test results tended to have low viral loads by a quantitative type-specific PCR assay. In the second study, cervical swab samples from 452 women (including 54 women with histologically confirmed cervical-intraepithelial neoplasia grade 2 or worse [>or= CIN2]) were tested initially by the hc2 and subsequently by the LBMA assay. The estimated sensitivities for >or= CIN2 were similar for the LBMA and hc2 assays (98.4% [95% CI, 95.0 to 100%] and 95.6% [95% CI, 89.2 to 100%], respectively). The percentages of negative results among 398 women without >or= CIN2 were similar for the LBMA and hc2 assays (45% and 50%, respectively). The repeat test reproducibility for 100 samples was 99.1% (kappa=0.92; 95% CI, 0.90 to 0.95). We conclude that the new LBMA assay will be useful for clinical and epidemiological research.

HPV infection in women: psychosexual impact of genital warts and intraepithelial lesions

INTRODUCTION

Genital Human Papillomavirus (HPV) infection is the most commonly occurring sexually transmitted viral infection in humans. HPV is a wide family of DNA viruses, which may cause benign skin and mucosal tumors (genital, anal, or oral warts), intraepithelial neoplasias, and/or malignant cancers in different organs. Women are more susceptible to the oncogenic effect of HPVs, mostly at the genital site on the uterine cervix.

AIMS

This review analyzes the impact of: (i) genital warts (GWs) and their treatment; (ii) HPV-related genital, oral, and anal precancerous lesions on women's sexual function.

METHODS

A Medline search was carried out. Search terms were HPV, GWs, intraepithelial neoplasia, cervical cancer, anal cancer, oral cancer, epidemiology, HPV risk factors, sexual dysfunctions, desire disorders, arousal disorders, dyspareunia, vulvar vestibulitis, vulvodynia, orgasmic difficulties, sexual repertoire, couple sexual problems, depression, anxiety, pap smear, screening program, therapy, and vaccines.

MAIN OUTCOME MEASURES

Sexual consequences of HPV infection in women, specifically GWs and intraepithelial HPV-related neoplasia.

RESULTS

Psychosexual vulnerability increases with number of recurrences of HPV infections. Depression, anxiety, and anger are the emotions most frequently reported. However, to date, there is no conclusive evidence of a specific correlation between HPV infection and a specific female sexual disorder. The relationship between HPV and vulvar vestibulitis/vulvodynia-related dyspareunia seems not to be direct. Counseling problems, the role of anti-HPV vaccine, and the concept of the high-risk partner are discussed. The reader is offered a practical approach with clinically relevant recommendations that may prove useful in his/her daily practice when dealing with HPV-infected women and couples.

CONCLUSION

The evidence of psychosexual consequences of HPV-related GWs and intraepithelial lesions is limited. Specific research on the sexual impact of GWs and intraepithelial HPV-related lesion in women is urgently needed.

Reducing the burden of glandular carcinomas of the uterine cervix

Widespread use of the Papanicolaou test for the screening of cervical cancers has lead to a significant decline in overall incidence and mortality rates over the past 3 decades. When different histologic types of cervical cancers are considered and trends are reexamined, it becomes apparent that observed declines are reflective of squamous cell carcinomas predominantly; the rates for adenocarcinomas continue to rise. This rise in incidence may be due to the greater difficulty in screening for glandular precursor lesions that often arise high within the endocervical canal. Reducing the incidence and mortality rates that are associated with adenocarcinomas can be accomplished by using improved screening techniques and large-scale implementation of cervical cancer vaccines that target the predominant oncogenic human papillomavirus types that are associated with adenocarcinoma.

Inter-laboratory validation of PCR-based HPV detection in pathology specimens

The detection and typing of human papilloma virus (HPV) in pathology specimens is gaining increasingly in importance. In the context of the initiative for quality assurance in pathology (QuIP) of the German Society of Pathology and the Professional Association of German Pathologists, four panel laboratories with experience and expertise in polymerase chain reaction (PCR)-based HPV detection were selected to establish an inter-laboratory trial. In a first step, these laboratories performed an internal testing of their own methodologies, which comprised DNA sequencing, multiplex nested PCR and hybridization techniques. Material from 39 samples including paraffin sections and DNA preparations of tissues and plasmids were evaluated by each panel institute according to their own protocols. Despite the different methodologies, a high degree of inter-laboratory reliability was achieved. In this report, we summarise the results. Pretested specimens are available for the external trail and can be ordered from the steering institute via provitro GmbH Berlin ( http://www.provitro.de ). Supplementary data are online available at http://pathologie-ccm.charite.de (rubric "Forschung"), which includes a web-based photo gallery of HPV-associated lesions and their potential association with specific virus types. The initiative is intended to foster the quality assurance of molecular HPV analysis in pathology and its correlation with morphological changes.

Immunization update

Although the development and licensure of new vaccines over the last 2 years has generated a lot of excitement as well as debate, there is a lot more to come. Not discussed in this article. licensure of another long-awaited vaccine albeit for use in adults was that for herpes zoster. The second HPV and rotavirus vaccines are awaiting approval in the US. Next in line are the vaccines both prophylactic as well as therapeutic against HIV. Topics of debate over the new vaccines include discussions amongst practices as to the affordability and cost of the new vaccines as well as the ethical debate amongst lawmakers and the general public regarding the rights and wrongs of compulsory vaccination against HPV. Another ongoing discussion is regarding the availability of approved vaccines. Shortages have been seen with several of the childhood vaccines including heptavalent pneumococcal conjugate vaccine, tetravalent meningococcal conjugate vaccine, hepatitis A vaccine, as well as the ongoing saga with influenza vaccines. Across the globe while the struggle against polio continues, there is encouraging news regarding the reduction in measles-related deaths, particularly in Africa. The last few years have indeed been landmark years in infectious disease research as the search continues for better and safer vaccines globally.

An armamentarium of wart treatments

Patients and clinicians experience the frustration of cutaneous viral warts caused by infection with the human papilloma virus (HPV).Warts appear in various forms on different sites of the body and include common warts (verruca vulgaris), plane or flat warts, myrmecia, plantar warts, coalesced mosaic warts, filiform warts, periungual warts, anogenital warts (venereal or condyloma acuminata), oral warts and respiratory papillomas. Cervical infection with HPV is now known to cause cervical cancer if untreated. A review of the medical literature reveals a huge armamentarium of wart monotherapies and combination therapies. Official evidence-based guidelines exist for the treatment of warts, but very few of the reported treatments have been tested by rigorous blinded, randomized controlled trials.Therefore, official recommendations do not often include treatments with reportedly high success rates, but they should not be ignored when considering treatment options. It is the purpose of this review to provide a comprehensive overview of the wart treatment literature to expand awareness of the options available to practitioners faced with patients presenting with problematic warts.

Chapter 3: HPV type-distribution in women with and without cervical neoplastic diseases

Geographical widespread data on human papillomavirus (HPV) type-distribution are essential for estimating the impact of HPV-16/18 vaccines on cervical cancer and cervical screening programmes. Epidemiological studies employing a variety of HPV typing protocols have been collated in meta-analyses. HPV-16/18 is estimated to account for 70% of all cervical cancers worldwide, although the estimated HPV-16/18 fraction is slightly higher in more developed (72-77%) than in less developed (65-72%) regions. About 41-67% of high-grade squamous intraepithelial lesion (HSIL), 16-32% of low-grade squamous intraepithelial lesion (LSIL) and 6-27% of atypical squamous cells of undetermined significance (ASCUS) are also estimated to be HPV-16/18-positive, thus highlighting the increasing relative frequency of HPV-16/18 with increasing lesion severity. After HPV-16/18, the six most common HPV types are the same in all world regions, namely 31, 33, 35, 45, 52 and 58; these account for an additional 20% of cervical cancers worldwide.