Detection of specific human papillomavirus types in paraffin-embedded sections of cervical carcinomas

Anogenital Human Papillomavirus (HPV) Infection, Seroprevalence, and Risk Factors for HPV Seropositivity Among Sexually Active Men Enrolled in a Global HPV Vaccine Trial

BACKGROUND

In men, the incidence of human papillomavirus (HPV)-related cancer is rising, but data regarding male HPV infection and seroprevalence are available from only a few countries.

METHODS

This analysis of a global HPV vaccine trial evaluated baseline data from 1399 human immunodeficiency virus-negative heterosexual men (HM) and men who have sex with men (MSM). Key objectives included assessment of HPV prevalence and risk factors for seropositivity to 9-valent HPV (9vHPV) vaccine types (6, 11, 16, 18, 31, 33, 45, 52, and 58), and concordance between seropositivity and prevalent HPV type.

RESULTS

Overall, 455 of 3463 HM (13.1%) and 228 of 602 MSM (37.9%) were HPV DNA positive for any 9vHPV vaccine type at baseline. Infection prevalence and seroprevalence (≥1 9vHPV vaccine type) were 13.2% and 8.1%, respectively, among 333 HM from Europe, and 37.9% and 29.9%, respectively, among 335 MSM from Europe or North America. Among men with baseline infection, MSM had higher seroprevalence for concordant HPV types (39.5% vs 10.8% in HM). The seropositivity risk (irrespective of baseline infection status) was higher among MSM versus HM (age-adjusted odds ratio, 3.0 [95% confidence interval, 2.4-6.4]). Among MSM, statistically significant seropositivity risk factors included younger age at sexual debut, higher number of receptive anal sex partners, and less frequent condom use. No factors assessed were associated with seropositivity in HM.

CONCLUSIONS

Higher proportions of MSM than HM were HPV DNA positive and seropositive, and concordance between HPV DNA positivity and seropositivity, a potential marker of true infection versus carriage, was higher in MSM. Most MSM and HM were seronegative for all 9vHPV vaccine types, suggesting the potential benefit of catch-up vaccination after sexual debut.Clinical Trials Registration. NCT00090285.

A high prevalence of human papillomavirus 16 and 18 co-infections in cervical biopsies from southern Brazil

HPV types 16 and 18 were studied in paraffin-fixed cervical biopsy collected in southern Brazil. HPV 16, HPV 18 and co-infection HPV 16/18 were identified in 10/57 (17.5%), 4/57 (7%) and in 43/57 (75.4%) samples, respectively. Southern Brazil has one of the highest prevalence rates of HPV 16/18 reported.

Methylation of the L1 gene and integration of human papillomavirus 16 and 18 in cervical carcinoma and premalignant lesions

High-risk human papillomavirus (HPV) is the primary cause of cervical carcinoma (CC). Viral integration into the host chromosomes is associated with neoplastic progression, and epigenetic changes may occur as a result. The objective of the present study was to analyze HPV L1 gene methylation and to compare the use of quantitative polymerase chain reaction (qPCR), in situ hybridization (ISH) and L1 methylation analysis as methods for detecting HPV integration. Cervical scrapes or biopsy samples positive for HPV 16 or 18, from 187 female patients with CC, squamous intraepithelial lesions (SILs) or no intraepithelial lesion (non-IL) were analyzed. Methylation of the L1 gene was determined using bisulfite modification followed by PCR, and HPV integration was subsequently analyzed. HPV 16 L1 gene methylation was revealed to increase with histological grade, with statistically significant differences observed as follows: Low-grade SIL vs. CC, P<0.0001 and non-IL vs. CC, P<0.0001. HPV 18 L1 gene methylation also increased according to histological grade, however, no statistically significant differences were observed. Methylation at CpG site 5608 of the HPV 16 L1 gene was associated with all grades of cervical lesions, whereas methylation at CpG site 5617 demonstrated the strongest association with CC (odds ratio, 42.5; 95% confidence interval, 4.7-1861; P<0.0001). The concordance rates between the various methods for the detection of the physical status of HPV 16 and HPV 18 were 96.1% for qPCR and ISH, 76.7% for qPCR and L1 gene methylation, and 84.8% for ISH and L1 gene methylation. In conclusion, methylation of the HPV 16 L1 gene increases significantly according to the grade of the cervical lesion, and methylation at CpG sites 5608 and 5617 of this gene may be used as prognostic biomarkers. ISH and L1 gene methylation have good concordance with qPCR with regards to the detection of HPV integration. Therefore, these are useful methods in determining the physical state of HPV.

High-risk human papilloma virus genotypes in cervical carcinoma of Serbian women: Distribution and association with pathohistological findings

A significant role of high-risk Human papilloma viruses (HR HPV) in the development of cervical carcinoma is well known. HR HPV 16 and 18 account for approximately 70% of all cases of cervical cancer worldwide. The incidence of cervical cancer in Serbia, is one of the highest in Europe. The aim of our study was to investigate the distribution of HR HPV types in cervical carcinoma of Serbian women, as well as association between the HPV types and pathohistological findings. The study included 80 archival cervical cancer tissues from the same number of patients. The presence of HPV DNA was determined using MY09/MY11 primers for L1 gene and GP1/GP2 primers for E1 gene. HPV was detected in 78.75% tissues. HR HPV genotypes found in the decreasing order of frequency were: HPV16 (80.39%), HPV33 (7.84%), HPV58 (5.88%), HPV18 (1.96%), HPV45 (1.96%) and HPV53 (1.96%). The examined tissues were 91.25% squamous cell carcinomas and 8.75% adenocarcinoma. The high frequency of HPV 16 was observed in both types of carcinoma (80.8% and 75%, respectively) while the prevalence of HPV18 was low. These results may contribute to the implementation of cervical carcinoma prevention program in Serbia, including the selection of the most appropriate vaccine and immunization program.

Intelligent screening systems for cervical cancer

Advent of medical image digitalization leads to image processing and computer-aided diagnosis systems in numerous clinical applications. These technologies could be used to automatically diagnose patient or serve as second opinion to pathologists. This paper briefly reviews cervical screening techniques, advantages, and disadvantages. The digital data of the screening techniques are used as data for the computer screening system as replaced in the expert analysis. Four stages of the computer system are enhancement, features extraction, feature selection, and classification reviewed in detail. The computer system based on cytology data and electromagnetic spectra data achieved better accuracy than other data.

Human papillomavirus type 16 viral load measurement as a predictor of infection clearance

Viral load measurements may predict whether human papillomavirus (HPV) type 16 infections may become persistent and eventually lead to cervical lesions. Today, multiple PCR methods exist to estimate viral load. We tested three protocols to investigate viral load as a predictor of HPV clearance. We measured viral load in 418 HPV16-positive cervical smears from 224 women participating in the Ludwig-McGill Cohort Study by low-stringency PCR (LS-PCR) using consensus L1 primers targeting over 40 known HPV types, and quantitative real-time PCR (qRT-PCR) targeting the HPV16 E6 and L1 genes. HPV16 clearance was determined by MY09/11 and PGMY PCR testing on repeated smears collected over 5 years. Correlation between viral load measurements by qRT-PCR (E6 versus L1) was excellent (Spearman's rank correlation, ρ = 0.88), but decreased for L1 qRT-PCR versus LS-PCR (ρ = 0.61). Viral load by LS-PCR was higher for HPV16 and related types independently of other concurrent HPV infections. Median duration of infection was longer for smears with high copy number by all three PCR protocols (log rank P<0.05). Viral load is inversely related to HPV16 clearance independently of concurrent HPV infections and PCR protocol.

Urothelial carcinoma with prominent squamous differentiation in the setting of neurogenic bladder: role of human papillomavirus infection

Squamous cell carcinomas of the urinary bladder are rare in the Western world; the majority of cases are reported in countries endemic to Schistosoma parasitic infections. Unlike squamous tumors of the uterine cervix or oropharynx, the human papillomavirus (HPV) is not commonly associated with bladder squamous cell carcinomas. We report on two cases of HPV-positive urothelial carcinomas of the urinary bladder with extensive squamous differentiation showing the typical basaloid, poorly differentiated morphology of HPV-associated tumors. These occurred in patients with neurogenic bladders who had long-standing histories of self-catheterization with tumors that tested positive for HPV by in situ hybridization. A retrospective review of our institutional database revealed four additional patients with bladder tumors showing squamous differentiation arising in the setting of neurogenic bladder. Review of these cases showed the more common well-differentiated keratinizing appearance of squamous cell carcinomas of the bladder. These tumors showed only patchy positivity for p16 immunohistochemical stain (not the diffuse strong staining seen in HPV-positive tumors), and the one tested case was negative for HPV by in situ hybridization. HPV infection and neurogenic bladder have been independently associated with increased risk of developing carcinoma in the urinary bladder; however, this is the first report of squamous tumors arising in the setting of concurrent neurogenic bladder and HPV infection. The morphology of these tumors is similar to that of other high-risk HPV-associated squamous carcinomas with a basaloid, poorly differentiated appearance and little to no keratin formation.

Human papillomavirus (HPV) detection using in situ hybridization in histologic samples: correlations with cytologic changes and polymerase chain reaction HPV detection

Although in situ hybridization (ISH) and polymerase chain reaction (PCR) have extensively been used on cytology specimens, there have been limited reports of the usefulness of these techniques in relation to confirmed histologic findings. In this study, we used PCR and ISH to detect human papillomavirus (HPV) in cytologic and histologic specimens, respectively. By using positive and negative likelihood ratios, we attempted to identify any predictive role of ISH testing alone or in combination with PCR for the development of high-grade histologic lesions (cervical intraepithelial neoplasia [CIN] 2+). In our study, ISH was a useful method for detection of HPV, even in a large fraction of samples with normal cytologic or biopsy findings. We suggest that when used together and evaluated in conjunction with histologic sections, ISH is a useful tool for ancillary molecular testing of HPV infection in cervical lesions, especially in CIN 2+ histological lesions where its analytic sensitivities and specificities were as good as those of PCR testing.

Efficacy of quadrivalent HPV vaccine against HPV Infection and disease in males

BACKGROUND

Infection with human papillomavirus (HPV) and diseases caused by HPV are common in boys and men. We report on the safety of a quadrivalent vaccine (active against HPV types 6, 11, 16, and 18) and on its efficacy in preventing the development of external genital lesions and anogenital HPV infection in boys and men.

METHODS

We enrolled 4065 healthy boys and men 16 to 26 years of age, from 18 countries in a randomized, placebo-controlled, double-blind trial. The primary efficacy objective was to show that the quadrivalent HPV vaccine reduced the incidence of external genital lesions related to HPV-6, 11, 16, or 18. Efficacy analyses were conducted in a per-protocol population, in which subjects received all three vaccinations and were negative for relevant HPV types at enrollment, and in an intention-to-treat population, in which subjects received vaccine or placebo, regardless of baseline HPV status.

RESULTS

In the intention-to-treat population, 36 external genital lesions were seen in the vaccine group as compared with 89 in the placebo group, for an observed efficacy of 60.2% (95% confidence interval [CI], 40.8 to 73.8); the efficacy was 65.5% (95% CI, 45.8 to 78.6) for lesions related to HPV-6, 11, 16, or 18. In the per-protocol population, efficacy against lesions related to HPV-6, 11, 16, or 18 was 90.4% (95% CI, 69.2 to 98.1). Efficacy with respect to persistent infection with HPV-6, 11, 16, or 18 and detection of related DNA at any time was 47.8% (95% CI, 36.0 to 57.6) and 27.1% (95% CI, 16.6 to 36.3), respectively, in the intention-to-treat population and 85.6% (97.5% CI, 73.4 to 92.9) and 44.7% (95% CI, 31.5 to 55.6) in the per-protocol population. Injection-site pain was significantly more frequent among subjects receiving quadrivalent HPV vaccine than among those receiving placebo (57% vs. 51%, P<0.001).

CONCLUSIONS

Quadrivalent HPV vaccine prevents infection with HPV-6, 11, 16, and 18 and the development of related external genital lesions in males 16 to 26 years of age. (Funded by Merck and others; ClinicalTrials.gov number, NCT00090285.).

Human papillomavirus infection induces NF-κB activation in cervical cancer: A comparison with penile cancer

This study aimed to determine the relationship between human papillomavirus (HPV) and nuclear factor-κB (NF-κB) in cervical cancer using 62 tissues of cervical cancer, and to compare the findings to penile cancer. HPV-DNA integration is a crucial factor for malignant transformation in cervical cancer and can be identified using in situ hybridization. Of the 62 cases, HPV infection was detected in 28 (45.2%). This frequency was lower than in penile cancer (68.2%) as shown by our previous study. The earliest age of onset of cervical and penile cancer was 18 and 35, respectively, whereas the mean age of the initial diagnosis of cervical and penile cancer was 50.1 and 59.6, respectively. The discrepancies of HPV prevalence, earliest ages of onset and mean ages between cervical and penile cancer patients may result from the gender-based synergistic action of HPV associated with multiple epidemiological co-factors. Of the 28 HPV-infected cases, NF-κB expression was observed in the nucleus in 18 (64.3%), in the cytoplasm in 19 (67.9%) and in the nucleus and/or cytoplasm in 27 cases (96.4%). The overexpression of NF-κB in cervical cancer cases suggests that NF-κB activation is a key modulator in driving chronic inflammation to cancer.

Evaluation of two commercialised in situ hybridisation assays for detecting HPV-DNA in formalin-fixed, paraffin-embedded tissue

INTRODUCTION

The role of human papilloma virus (HPV) in the pathogenesis of anogenital dysplasia is now conclusive. However, HPV detection in formalin-fixed and paraffin-embedded tissues remains controversial. Therefore, the aim of this study was to evaluate morphological changes directly in tissue specimens using a HPV-DNA detection system involving HPV in situ hybridisation.

MATERIALS AND METHODS

Samples from patients with cervical carcinoma were analysed using the GenPoint HPV DNA Probe Cocktail (Dako, Glostrup, Denmark) and the ZytoFast HPV Screening CISH-Kit (Zytomed, Berlin, Germany). Three cervical carcinoma cell lines with a well-defined HPV copy number per cell (SiHa, HeLa, and CaSki) served as positive controls for sensitivity testing, while two HPV-negative cell lines (AC-1M32, MCF-7) and brain tissue samples served as negative controls. Moreover, to assess the validity of the in situ hybridisation, the expression of HPV-16 DNA in cell lines was demonstrated by HPV-16 E6-specific PCR.

RESULTS

Both HPV-screening assays revealed strong signals of episomal and integrated HPV-DNA at a HPV copy number of more than 50 copies/cell. All cervical carcinoma samples were positive in the Dako assay, which identifies 13 high-risk HPV genotypes, whereas HPV-DNA could be detected in 9/10 cervical carcinoma samples using the Zytofast assay, identifying HPV 16, 18, 31, 33, and 35.

CONCLUSION

HPV in situ hybridisation is a convenient and powerful tool for detecting HPV-DNA in formalin-fixed and paraffin-embedded tissue samples. Therefore, this technique is suitable for analysis of a potential HPV infection using archival pathological slides.

Automated analysis of fluorescent in situ hybridization (FISH) labeled genetic biomarkers in assisting cervical cancer diagnosis

The numerical and/or structural deviation of some chromosomes (i.e., monosomy and _polysomy of chromosomes 3 and X) are routinely used as positive genetic biomarkers to diagnose cervical cancer and predict the disease progression. Among the available diagnostic methods to analyze the aneusomy of chromosomes 3 and X, fluorescence in situ hybridization (FISH) technology has demonstrated significant advantages in assisting clinicians to more accurately detect and diagnose cervical carcinoma at an early stage, in particular for the women at a high risk for progression of low-grade and high-grade squamous intra-epithelium lesions (LSIL and HSIL). In order to increase the diagnostic accuracy, consistency, and efficiency from that of manual FISH analysis, this study aims to develop and test an automated FISH analysis method that includes a two-stage scheme. In the first stage, an interactive multiple-threshold algorithm is utilized to segment potential interphase nuclei candidates distributed in different intensity levels and a rule-based classifier is implemented to identify analyzable interphase cells. In the second stage, FISH labeled biomarker spots of chromosomes 3 and X are segmented by a top-hat transform. The independent FISH spots are then detected by a knowledge-based classifier, which enables recognition of the splitting and stringy FISH signals. Finally, the ratio of abnormal interphase cells with numerical changes of chromosomes 3 and X is calculated to detect positive cases. The experimental results of four test cases showed high agreement of FISH analysis results between the automated scheme and the cytogeneticist's analysis including 92.7% to 98.7% agreement in cell segmentation and 4.4% to 11.0% difference in cell classification. This preliminary study demonstrates the feasibility of potentially applying the automatic FISH analysis method to expedite the screening and detecting cervical cancer at an early stage.

Automated detection and analysis of fluorescent in situ hybridization spots depicted in digital microscopic images of Pap-smear specimens

Fluorescence in situ hybridization (FISH) technology has been widely recognized as a promising molecular and biomedical optical imaging tool to screen and diagnose cervical cancer. However, manual FISH analysis is time-consuming and may introduce large inter-reader variability. In this study, a computerized scheme is developed and tested. It automatically detects and analyzes FISH spots depicted on microscopic fluorescence images. The scheme includes two stages: (1) a feature-based classification rule to detect useful interphase cells, and (2) a knowledge-based expert classifier to identify splitting FISH spots and improve the accuracy of counting independent FISH spots. The scheme then classifies detected analyzable cells as normal or abnormal. In this study, 150 FISH images were acquired from Pap-smear specimens and examined by both an experienced cytogeneticist and the scheme. The results showed that (1) the agreement between the cytogeneticist and the scheme was 96.9% in classifying between analyzable and unanalyzable cells (Kappa=0.917), and (2) agreements in detecting normal and abnormal cells based on FISH spots were 90.5% and 95.8% with Kappa=0.867. This study demonstrated the feasibility of automated FISH analysis, which may potentially improve detection efficiency and produce more accurate and consistent results than manual FISH analysis.

HPV in situ hybridization signal patterns as a marker for cervical intraepithelial neoplasia progression

OBJECTIVE

HPV-DNA integration is one factor for malignant transformation and can be identified using in situ hybridization (ISH), where a diffuse signal represents episomal HPV and punctate, integrated. The aim is to verify if a punctate pattern could be a marker of CIN1 that progresses.

METHODS

74 CIN1 biopsies were studied. In the follow up, a second biopsy was performed and 65% showed CIN1 or no lesion (group without progression) and 35% CIN2/3 (with progression). ISH was carried out with HR-HPV GenPoint in the first biopsy looking for the positive distribution in epithelium regions (basal, intermediate, superficial) and reaction pattern (diffuse and punctate). The Mann-Whitney and Fisher tests were used to compare the groups (p<or=0.05).

RESULTS

The mean age of patients without progression was 26 and, with progression 31 (p=0.02). ISH was positive in 22 cases, 8 with CIN2/3 in the second biopsy. The punctate signal was observed in all epithelial layers, and the mean coefficient between the number of cells with punctate and diffuse signals was 3.5 times more common in the progression group (p=0.08). The average percentage of punctate nuclei patterns in the basal region in cases without progression was 0.5% and 11% in those with progression (p=0.05). However, in superficial layer this was not correlated with progression.

CONCLUSION

Progression was observed in 35% of CIN1 and associated with age; 30% of the cases were positive by ISH, but must be carefully interpreted. Punctate signals were related to progression only in basal cells, identifying CIN1 with potentially aggressive behavior.

Prophylactic HPV vaccines: new interventions for cancer control

Human Papillomavirus (HPV) infection causes cervical cancer, a significant portion of anal, vulvar, vaginal, and oropharyngeal cancers, genital warts, and recurrent respiratory papillomatosis (RRP). HPV 16 and 18 cause 70-90% of HPV-related cancers whereas HPV 6 and 11 cause 90% of RRP and genital wart cases. Together these four types cause 30-50% of all cervical intraepithelial neoplasia such as those detected by Papinicalou screening. In June 2006, a quadrivalent HPV (6, 11, 16, 18) vaccine was licensed in the United States, and subsequently in the European Union (September 2006), both following expedited review. We describe the primary objectives of the quadrivalent HPV vaccine clinical trial program including studies in females aged 9-45 and males aged 9-26. Planned long-term efficacy and safety evaluations, as well as programs to evaluate vaccine impact on oropharyngeal cancer are also described.

A novel algorithm for reliable detection of human papillomavirus in paraffin embedded head and neck cancer specimen

Human papillomavirus type 16 (HPV16) plays a role in the development of a subgroup of head and neck squamous cell carcinomas (HNSCC). However, uncertainty exists about the true impact of HPV in this tumor type as conflicting reports have been published with prevalence rates from 0 to 100%. We aimed to find a detection algorithm of a biologically and thus clinically meaningful infection, applicable for high-throughput screening of frozen and formalin-fixed paraffin embedded (FFPE) specimens. By considering detection of HPV E6 oncogene expression in frozen biopsies as gold standard for a meaningful HPV infection, the value of several assays was evaluated on FFPE tumor specimens and sera of 48 HNSCC patients. The following assays were evaluated on FFPE tissue samples: HPV DNA general primer (GP)5+/6+ PCR, viral load analysis, HPV16 DNA FISH detection, HPV16 E6 mRNA RT-PCR, p16 immunostaining, and on corresponding serum samples detection of antibodies against the HPV16 proteins L1, E6 and E7. Comparing single assays on FFPE tissue samples detection of E6 expression by RT-PCR was superior, but application remains at present limited to HPV16 detection. Most suitable algorithm with 100% sensitivity and specificity appeared p16 immunostaining followed by GP5+/6+ PCR on the p16-positive cases. We show that clinically meaningful viral HPV infections can be more reliably measured in FFPE HNSCC samples in a standard and high throughput manner, paving the way for prognostic and experimental vaccination studies, regarding not only HNSCC, but possibly also cancer types with HPV involvement in subgroups such as penile and anal cancer.

Effect of prophylactic human papillomavirus L1 virus-like-particle vaccine on risk of cervical intraepithelial neoplasia grade 2, grade 3, and adenocarcinoma in situ: a combined analysis of four randomised clinical trials

BACKGROUND

Cervical cancer and its obligate precursors, cervical intraepithelial neoplasia grades 2 and 3 (CIN2/3), and adenocarcinona in situ (AIS), are caused by oncogenic human papillomavirus (HPV). In this combined analysis of four clinical trials we assessed the effect of prophylactic HPV vaccination on these diseases.

METHODS

20,583 women aged 16-26 years were randomised to receive quadrivalent HPV6/11/16/18 vaccine (n=9087), its HPV16 vaccine component (n=1204), or placebo (n=10 292). They underwent periodic Papanicolaou testing, with colposcopy or biopsy for detected abnormalities. The primary composite endpoint was the combined incidence of HPV16/18-related CIN2/3, AIS, or cervical cancer. These trials are registered at ClinicalTrials.gov, numbers NCT00365378, NCT00365716, NCT00092521, and NCT00092534.

FINDINGS

Mean follow-up was 3.0 years (SD 0.66) after first dose. In women negative for HPV16 or HPV18 infection during the vaccination regimen (n=17 129, per protocol), vaccine efficacy was 99% for the primary endpoint (95% CI 93-100), meeting the statistical criterion for success. In an intention-to-treat analysis of all randomised women (including those who were HPV16/18 naive or HPV16/18-infected at day 1), efficacy was 44% (95% CI 31-55); all but one case in vaccine recipients occurred in women infected with HPV16 or HPV18 before vaccination. In a second intention-to-treat analysis we noted an 18% reduction (95% CI 7-29) in the overall rate of CIN2/3 or AIS due to any HPV type.

INTERPRETATION

Administration of HPV vaccine to HPV-naive women, and women who are already sexually active, could substantially reduce the incidence of HPV16/18-related cervical precancers and cervical cancer.

Efficacy of a quadrivalent prophylactic human papillomavirus (types 6, 11, 16, and 18) L1 virus-like-particle vaccine against high-grade vulval and vaginal lesions: a combined analysis of three randomised clinical trials

BACKGROUND

Vulval and vaginal cancers among younger women are often related to infection with human papillomavirus (HPV). These cancers are preceded by high-grade vulval intraepithelial neoplasia (VIN2-3) and vaginal intraepithelial neoplasia (VaIN2-3). Our aim was to do a combined analysis of three randomised clinical trials to assess the effect of a prophylactic quadrivalent HPV vaccine on the incidence of these diseases.

METHODS

18 174 women (16-26 years) were enrolled and randomised to receive either quadrivalent HPV6/11/16/18 L1 virus-like-particle vaccine or placebo at day 1, and months 2 and 6. Individuals underwent detailed anogenital examination at day 1, 1 month after dose three, and at 6-12-month intervals for up to 48 months. Suspect genital lesions were biopsied and read by a panel of pathologists and vaccine HPV type-specific DNA testing was done. The primary endpoint was the combined incidence of VIN2-3 or VaIN2-3 associated with HPV16 or HPV18. Primary efficacy analyses were done in a per-protocol population.

FINDINGS

The mean follow-up time was 3 years. Among women naive to HPV16 or HPV18 through 1 month after dose three (per-protocol population; vaccine n=7811; placebo n=7785), the vaccine was 100% effective (95% CI 72-100) against VIN2-3 or VaIN2-3 associated with HPV16 or HPV18. In the intention-to-treat population (which included 18 174 women who, at day 1, could have been infected with HPV16 or HPV18), vaccine efficacy against VIN2-3 or VaIN2-3 associated with HPV16 or HPV18 was 71% (37-88). The vaccine was 49% (18-69) effective against all VIN2-3 or VaIN2-3, irrespective of whether or not HPV DNA was detected in the lesion. The most common treatment-related adverse event was injection-site pain.

INTERPRETATION

Prophylactic administration of quadrivalent HPV vaccine was effective in preventing high-grade vulval and vaginal lesions associated with HPV16 or HPV18 infection in women who were naive to these types before vaccination. With time, such vaccination could result in reduced rates of HPV-related vulval and vaginal cancers.

The natural history of cervical HPV infection: unresolved issues

The identification of high-risk human papillomavirus (HPV) types as a necessary cause of cervical cancer offers the prospect of effective primary prevention and the possibility of improving the efficiency of cervical screening programmes. However, for these opportunities to be realized, a more complete understanding of the natural history of HPV infection, and its relationship to the development of epithelial abnormalities of the cervix, is required. We discuss areas of uncertainty, and their possible effect on disease prevention strategies.