A prospective study of age trends in cervical human papillomavirus acquisition and persistence in Guanacaste, Costa Rica

Vaccination HPV: principes, résultats et perspectives

Human papillomavirus (HPV) are responsible of an important morbidity and mortality. HPV is a significant source of morbidity and mortality. HPV is the most common sexually transmitted infection: adolescents are at high-risk for HPV acquisition. Biologic and epidemiologic studies have demonstrated that HPV infection is a necessary but non-sufficient cause of cervical cancer and genital warts. The vast majority of cervical cancers contain high-risk HPV type and approximately 70% contain HPV types 16 or 18. HPV types 6 or 11 are responsible for approximately 90% of genital warts. Thus, a vaccine that could prevent. Prophylactic vaccines based on the use of virus-like particles (VLPs) obtained by auto-assembly of L1 are under clinical trials. Two vaccines are currently evaluated: Cervarix (GlaxoSmithKline Biologics), a bivalent vaccine against HPV 16 and 18, and Gardasil (Merck & Co) a quadrivalent vaccine against HPV 16, 18, 6, and 11. Phase I, II and III studies have demonstrated that both vaccines are well tolerated and provide an excellent immunogenicity. With approximately 5-year follow-up, both vaccines have been effective in preventing persistent infection with targeted HPV types and in preventing cervical intraepithelial lesions. The optimal target for vaccination is probably 12-year-old girls.

Alternating high-risk human papillomavirus infection: consequences of progression to cervical intraepithelial neoplasia

BACKGROUND

Nearly every Dutch woman will be exposed to genital human papillomavirus (HPV) at least once during her lifetime, and most likely several times. In the current study, the authors investigated the prevalence of high-risk-HPV (HR-HPV) infection and the likelihood of progression to cervical intraepithelial neoplasia (CIN).

METHODS

In this study, the course of HR-HPV infection in 703 women was observed. From a database of 720,016 negative cytology smears, the authors selected 703 women based on the availability of at least 2 HR-HPV polymerase chain reaction tests. The authors database stores not only the HPV data but also all other cytologic and histologic data, allowing the detection of women who progressed from negative cytology to CIN within a period of 10 years.

RESULTS

Of the 703 selected women, 159 were found to have alternating HR-HPV infection (change from a negative HR-HPV test to a positive test or vice versa), 40 had a persistently positive HR-HPV test, and 504 women had a persistently negative HR-HPV test. The percentage of alternating HPV infection declined over time from 37% to 7%. Of the women age older than 40 years, 17% had an alternating HR-HPV infection, 2 of whom developed CIN. These findings led the authors to conclude that all the women in the current study with an increased risk of developing type 2 or 3 CIN were identified using 2 HPV tests. Women age older than 40 years still have a significant risk of acquiring a HR-HPV.

CONCLUSIONS

In light of the current study findings, the authors believe it is worth considering the inclusion of women age 40 years and older who have negative cytology for HPV testing as part of the Dutch national screening program.

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.

Prevalence of the most common high-risk HPV genotypes among women in three new independent states of the former Soviet Union

Type distribution of HPV has been studied in different geographic regions, but the data are scanty from the new independent states of the former Soviet Union. Here the HPV prevalence and distribution of the most frequent high-risk HPV types among 3,187 women at different risk for HPV and cervical intraepithelial neoplasia in Russia, Belarus, and Latvia is reported. HPV detection, type distribution and viral load analysis in DNA samples from cervical scrapes were done with real-time PCR-based assay detecting HPV types 16, 18, 31, 33, 35, 39, 45, 52, and 58. The overall HPV prevalence was 31.2%, HPV16 was the most prevalent type followed by HPV31 and HPV33 group. The overall HPV prevalences in Russia, Belarus and Latvia were 33.4%, 27.5%, and 26.2%. The type distributions were similar in these countries, except for Latvia where HPV39 was the third prevalent genotype. HPV prevalence was highest (40.8%) among women from sexually transmitted disease clinic, followed by 30.9% among gynecological outpatients and 27.2% in screening patients. HPV detection increased with cytological abnormality (P = 0.0001) and lesion grade in the biopsy (P = 0.0001), from 27% to 72% in normal samples to cancer, and from 64% to 77% in cervical intraepithelial neoplasia 1 to cancer. The normalized viral loads varied greatly between and among different HPV-types. The mean log HPV33 group copies/cell increased from negative for intraepithelial lesions to cancer (P = 0.049). Distribution of the most common high-risk HPV-types seems to be similar in these countries as reported in other major geographical regions.

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.

Variations in the age-specific curves of human papillomavirus prevalence in women worldwide

An inverse relationship between age and human papillomavirus (HPV) prevalence has been reported in many developed countries, but information on this relationship is scarce in many other parts of the world. We carried out a cross-sectional study of sexually active women from the general population of 15 areas in 4 continents. Similar standardised protocols for women's enrolment, cervical specimen collection and PCR-based assays for HPV testing were used. HPV prevalence in different age groups was compared by study area. 18,498 women aged 15-74 years were included. Age-standardised HPV prevalence varied more than 10-fold between populations, as did the shape of age-specific curves. HPV prevalence peaked below age 25 or 35, and declined with age in Italy, the Netherlands, Spain, Argentina, Korea and in Lampang, Thailand and Ho Chi Minh, Vietnam. This was not the case in Songkla, Thailand nor Hanoi, Vietnam, where HPV prevalence was low in all age groups. In Chile, Colombia and Mexico, a second peak of HPV prevalence was detected among older women. In the poorest study areas in Asia (Shanxi, China and Dindigul, India), and in Nigeria, HPV prevalence was high across all age groups. The substantial differences observed in age-specific curves of HPV prevalence between populations may have a variety of explanations. These differences, however, underline that great caution should be used in inferring the natural history of HPV from age-specific prevalences.

Human papillomavirus types among women infected with HIV: a meta-analysis

BACKGROUND

HIV-positive women have a high prevalence of human papillomavirus (HPV) infection and are infected with a broader range of HPV types than HIV-negative women. It is not known to what extent these different types are associated with high-grade squamous intraepithelial lesions (HSIL) and cancer.

METHODS

Meta-analysis of HPV type-specific prevalence among HIV-positive women, stratified by geographical region and by cervical cytology: normal, atypical squamous cells of undetermined significance/low-grade squamous intraepithelial lesions (ASCUS/LSIL) or HSIL.

RESULTS

In 20 studies, 5578 HIV-positive women were identified, largely from North America but also Africa, Asia, Europe and South/Central America. For 3230 with no cytological abnormalities, prevalence was 36.3% for any HPV and 11.9% for multiple HPV types. The six most common high-risk HPV types were 16 (4.5%), 58 (3.6%), 18 (3.1%), 52 (2.8%), 31 (2.0%) and 33 (2.0%). HPV16 was also the most common type in 2053 HIV-positive women with ASCUS/LSIL and 295 with HSIL. Those with HSIL were significantly less likely to be infected with HPV16 (odds ratio, 0.6; 95% confidence interval, 0.4-0.7) than the general female population with HSIL. In contrast, HIV-positive women with HSIL were significantly more likely to be infected with HPV types 11, 18, 33, 51, 52, 53, 58 and 61, and with multiple HPV types.

CONCLUSIONS

The proportion of HIV-positive women with HPV16 rose with increasing severity of cervical lesions. Nevertheless, HPV16 remained underrepresented in HIV-positive women with HSIL, who showed a higher proportion of other HPV types and multiple types compared with the general female population with HSIL.

Prospective evaluation of the Hybrid Capture 2 and AMPLICOR human papillomavirus (HPV) tests for detection of 13 high-risk HPV genotypes in atypical squamous cells of uncertain significance

The use of high-risk human papillomavirus (hrHPV) testing as an adjunct to cervical cytology in population-based screening programs is currently based on DNA hybridization and PCR assays. The aim of this study was to prospectively assess the diagnostic performance of the Hybrid Capture 2 test (HC2; Digene Corporation) in comparison with that of the recently developed PCR-based AMPLICOR HPV test (Roche Molecular Systems) for the detection of 13 hrHPV types. A reverse line blot hybridization assay (Innogenetics) was used as an internal reference standard in discordant cases. Two hundred seventy-one patients with atypical squamous cells of uncertain significance (ASCUS) in cervical samples underwent hrHPV testing. The chi-square test was performed to compare respective proportions. Totals of 160/271 (59%) and 156/271 (58%) were found to be positive for hrHPV with HC2 and AMPLICOR, respectively. Concordant results were obtained for 235 (86.7%) of the 271 samples (kappa statistic, 0.73 +/- 0.04). Considering types 26, 53, and 66 as oncogenic types, negative predictive values (NPVs) of HC2 and AMPLICOR were 92.8% and 87.8%, respectively (difference was not significant), and their respective accuracies were 94.8% and 91.9% (difference was not significant). Considering types 26, 53, and 66 as not oncogenic, the respective HC2 and AMPLICOR NPVs were 92.8% and 97.4% (difference was not significant), and accuracy was significantly higher for the AMPLICOR assay (95.9% versus 90.8% for HC2) (P<0.05). For ASCUS samples, the NPV was 92.8% for HC2 testing and might be compromised if the copy number of HPV DNA was low. The NPV was 97.4% for the AMPLICOR assay and might be compromised if HPV types 26, 53, and 66 were considered oncogenic. The accuracy of these two assays is good and is compatible with routine clinical use in the triage of ASCUS cases.

Human papillomavirus testing in primary cervical screening and abnormal Papanicolaou management

Human papillomavirus (HPV) infection is a necessary cause of cervical cancer; HPV testing capitalizes on this fact to maximize the clinical benefits of cervical screening and abnormal Papanicolaou (Pap) test management. HPV tests in combination with Pap tests are 96% to 100% sensitive for detection of cervical intraepithelial neoplasia (CIN) 2/3 and cancer. However, because HPV infection is common in young women and most commonly transient, HPV testing is not recommended as part of primary cervical screening for women younger than 30 years of age. HPV testing is recommended for women of any age for the clarification of atypical cells of undetermined significance (ASC-US) and as an option for follow-up of women with HPV-positive ASC-US, atypical squamous cells "cannot rule out high-grade," or low-grade squamous intraepithelial lesions not found to have CIN 2/3. HPV testing is also recommended as an alternative to colposcopy and/or cytology for follow-up of treated cases. Proper use of HPV testing improves the management of women with cytologic abnormalities. In addition, a negative HPV test in combination with a normal Pap test result in women age 30 and older allows the safe extension of the interval between cervical screenings. Thus, when used properly, HPV testing may reduce morbidity and mortality and do so in a cost-effective manner.

Relationships of Human Papillomavirus Type, Qualitative Viral Load, and Age with Cytologic Abnormality

Persistent cervical infections with carcinogenic human papillomaviruses (HPV) cause virtually all cervical cancer. Cytologic abnormalities are the manifestations of HPV infections used to identify women at risk. To compare the potential of the full range of anogenital HPV genotypes to induce cytopathic effects, we examined the influences of HPV type, viral load, and age on cytopathology among 1,222 women having a single HPV type at enrollment into a 10,000-woman population-based study in Costa Rica. Cervical specimens were tested for approximately 40 HPV types by MY09/MY11 L1 primer PCR and type-specific dot blot hybridization. Types were organized by phylogenetic species and cancer risk. PCR signal strength served as a qualitative surrogate for viral load. Overall, 24.8% [95% confidence interval (95% CI), 22.4-27.3] of single prevalent HPV infections had concurrent abnormalities (atypical squamous cells or worse) ranging from 0.0% to 80.0% based on HPV type. Noncarcinogenic alpha3/alpha15 types, although highly prevalent, uncommonly caused cytologic abnormalities (13.1%; 95% CI, 9.8-17.0). In contrast, one quarter to nearly one half of infections with a single major carcinogenic species type (alpha9/alpha11/alpha7/alpha5/alpha6) produced abnormalities. Greater abnormalities were observed with increasing qualitative viral load of carcinogenic types; fewer abnormalities were observed among older women (>54 years). A high percentage (46.2%) of detected abnormalities in women infected with HPV16 or related alpha9 types were high grade or worse, consistent with strong carcinogenicity, compared with 10.7% in women infected with alpha7 types, including HPV18, a major cause of adenocarcinoma. The lack of evident severe abnormalities associated with HPV18 and related HPV types might have implications for screening for poorly detected glandular and alpha7-related lesions.

Infectious Agents

There is substantial evidence that infectious agents play a causal role in a variety of human malignancies. These cancers include the liver, cervix, stomach, nasopharynx, bladder, and bile duct as well as Kaposi sarcoma (KS) and several lymphomas. This chapter summarizes the biological and epidemiologic features of each of the major oncogenic infections, beginning with the viruses, followed by H. pylori, and with a brief summary of the relevant parasites.

Relationship between prevalent oral and cervical human papillomavirus infections in human immunodeficiency virus-positive and -negative women

Human papillomavirus (HPV) is an etiologic agent for both oropharyngeal and cervical cancers, yet little is known about the interrelationship between oral and cervical HPV infections. Therefore, we compared the prevalences and type distributions of oral and cervical HPV infections and evaluated infection concordance in a cross-sectional study within the Women's Interagency HIV Study cohort. Oral rinse and cervical-vaginal lavage samples were concurrently collected from a convenience sample of 172 human immunodeficiency virus (HIV)-positive and 86 HIV-negative women. HPV genomic DNA was detected by PGMY09/11 L1 consensus primer PCR and type specified by reverse line blot hybridization for 37 HPV types and beta-globin. Only 26 of the 35 HPV types found to infect the cervix were also found within the oral cavity, and the type distribution for oral HPV infections appeared distinct from that for cervical infections (P<0.001). Oral HPV infections were less common than cervical infections for both HIV-positive (25.2% versus 76.9%, P<0.001) and HIV-negative (9.0% versus 44.9%, P<0.001) women. Oral HPV infections were more common among women with a cervical HPV infection than those without a cervical HPV infection (25.5% versus 7.9%, P=0.002). The majority of women (207; 93.7%) did not have simultaneous oral and cervical infections by the same HPV type; however, the number of women who did (14; 6.3%) was significantly greater than would be expected by chance (P=0.0002). Therefore, the oral and cervical reservoirs for HPV infection are likely not entirely independent of one another.

The epidemiology of genital human papillomavirus infection

Clinical and subclinical human papillomavirus (HPV) infections are the most common sexually transmitted infections in the world, and most sexually-active individuals are likely to be exposed to HPV infection during their lifetimes. More than 40 genotypes of HPV infect the epithelial lining of the anogenital tract and other mucosal areas of the body; of these, 13-18 types are considered to be high-oncogenic risk HPV types (HR-HPV). Persistent infection with HR-HPVs is now unequivocally established as a necessary cause of cervical cancer and is likely to be responsible for a substantial proportion of other anogenital neoplasms and upper aero-digestive tract cancers. Low oncogenic risk HPV types (LR-HPV) are also responsible for considerable morbidity as the cause of genital warts. Youth and certain sexual characteristics are key risk factors for HPV acquisition and persistence of HPV infection, but other mediating factors include smoking, oral contraceptive (OC) use, other STIs (e.g. chlamydia, herpes simplex virus), chronic inflammation, immunosuppressive conditions including HIV infection, parity, dietary factors, and polymorphisms in the human leukocyte antigen system. Not surprisingly, these factors are also established or candidate cofactors identified in epidemiologic studies of cervical cancer. HPV transmissibility and molecular events in HPV-induced carcinogenesis have been the focus of recent multidisciplinary epidemiologic studies. This shift in research focus coincides with a shift in cancer prevention techniques towards immunization with HPV vaccines and HPV testing of precancerous lesions.

Human Papillomavirus Type 16 and 18 Variants: Race-Related Distribution and Persistence

BACKGROUND

Analogous to the geographic distribution of variants of human papillomavirus (HPV) types, the distribution and persistence of these variants among infected individuals may be related to the racial composition of a population living in one geographic region.

METHODS

We studied 1114 women in the United States participating in the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study who were positive for HPV16 and/or HPV18 at enrollment. Race was self-reported. HPV samples were characterized by sequencing the E6 gene and part of the long control region and classified as variants according to established lineages. Subjects were examined for HPV every 6 months for 2 years. All statistical tests were two-sided.

RESULTS

HPV18 African variants were predominant in the 97 HPV18-infected African American women (i.e., 62 women or 63.9%, 95% confidence interval [CI] = 53.5% to 73.4%), and European variants were common in the 168 HPV18-infected white women (i.e., 91 women or 54.2%, 95% CI = 46.3% to 61.9%). HPV16 African variants accounted for 43 (26.5%, 95% CI = 19.9% to 34.0%) of the infections in the 162 HPV16-infected African American women but for only 25 (4.3%, 95% CI = 2.8% to 6.3%) in the 584 HPV16-infected white women. The likelihood of remaining HPV18 positive was statistically significantly higher in white women infected with European than in white women infected with African variants (P = .04); the reverse was observed in African American women (P = .03). A similar pattern was observed for persistence of HPV16 variants, with the likelihood of remaining positive being higher for white women, but lower for African American women, infected with an European variant than with an African variant (P = .03 and P = .16, respectively).

CONCLUSIONS

Variants of HPV16 and HPV18 appear to persist longer in a host whose race indicates an ancestral geographic distribution that was once shared with that of the variant-i.e., European variants persist longer in white women, and African variants persist longer in African American women.

Chapter 9: Clinical applications of HPV testing: A summary of meta-analyses

BACKGROUND

More than ever, clinicians need regularly updated reviews given the continuously increasing amount of new information regarding innovative cervical cancer prevention methods.

MATERIAL AND METHODS

A summary is given from recently published meta-analyses on three possible clinical applications of human papillomavirus (HPV)-DNA testing: triage of women with equivocal or low-grade cytological abnormalities; prediction of the therapeutic outcome after treatment of cervical intraepithelial neoplasia (CIN) lesions, and last not but not least, primary screening for cervical cancer and pre-cancer.

RESULTS

Consistent evidence is available indicating that HPV-triage with the Hybrid Capture-2 assay (HC2) is more accurate (significantly higher sensitivity, similar specificity) than repeat cytology to triage women with equivocal Pap smear results. When triaging women with low-grade squamous intraepithelial lesions (LSIL), a reflex HC2 test does not show a significantly higher sensitivity, but a significantly lower specificity compared to a repeat Pap smear. After treatment of cervical lesions, HPV testing easily detects (with higher sensitivity and not lower specificity) residual or recurrent CIN than follow-up cytology. Primary screening with HC2 generally detects 23% (95% confidence interval, CI: 13-23%) more CIN-2, CIN-3, or cancer compared to cytology at cut-off atypical squamous cells of undetermined significance (ASCUS) or LSIL, but is 6% (95% CI: 4-8%) less specific. By combined HPV and cytology screening, a further 4% (95% CI: 3-5%) more CIN-3 lesions can be identified but at the expense of a 7% (95% CI: 5-9%) loss in specificity, in comparison with isolated HC2 screening.

CONCLUSIONS

Sufficient evidence exists to recommend HPV testing in triage of women with atypical cytology and in surveillance after treatment of CIN lesions. In the United States, recently reviewed knowledge has resulted in the approval of combined cytology and HC2 primary screening in women older than 30 years. However, in Europe, cytology-based screening still remains the standard screening method. The European screening policy will be reviewed based on the longitudinal results of randomised population trials which are currently underway.

Genital human papillomavirus infection

Over the past few decades, epidemiology and natural history studies have led to improved understanding of human papillomavirus (HPV) infection and to promising prevention strategies. HPV infection is the cause of anogenital warts and cervical cancer, as well as a proportion of other anogenital and head and neck cancers. Data from clinical trials have resulted in recommendations that support the use of an HPV test in the context of cervical cancer screening and management. Prophylactic HPV vaccine trials have demonstrated high efficacy, and an HPV vaccine that prevents cervical cancer precursors, cervical cancer, and anogenital warts caused by HPV types 6, 11, 16, and 18 was licensed for use in girls and women aged 9-26 years by the US Food and Drug Administration (FDA) in June 2006. In this article, we review genital HPV for the clinician, with a primary focus on the prevalence of HPV infection in the United States.

Human papillomavirus genotype distribution and cervical squamous intraepithelial lesions among high-risk women with and without HIV-1 infection in Burkina Faso

Human papillomavirus (HPV) infection and cervical squamous intraepithelial lesions (SILs) were studied in 379 high-risk women. Human papillomavirus DNA was detected in 238 of 360 (66.1%) of the beta-globin-positive cervical samples, and 467 HPV isolates belonging to 35 types were identified. Multiple (2-7 types) HPV infections were observed in 52.9% of HPV-infected women. The most prevalent HPV types were HPV-52 (14.7%), HPV-35 (9.4%), HPV-58 (9.4%), HPV-51 (8.6%), HPV-16 (7.8%), HPV-31 (7.5%), HPV-53 (6.7%), and HPV-18 (6.4%). Human immunodeficiency virus type 1 (HIV-1) seroprevalence was 36.0%. Human papillomavirus prevalence was significantly higher in HIV-1-infected women (87 vs 54%, prevalence ratio (PR) = 1.61, 95% confidence interval (CI): 1.4-1.8). High-risk HPV types (71 vs 40%, PR = 1.79, 95% CI: 1.5-2.2), in particular HPV-16+18 (22 vs 9%, PR = 2.35, 95% CI: 1.4-4.0), and multiple HPV infections (56 vs 23%, PR = 2.45, 95% CI: 1.8-3.3) were more prevalent in HIV-1-infected women. High-grade SIL (HSIL) was identified in 3.8% of the women. Human immunodeficiency virus type 1 infection was strongly associated with presence of HSIL (adjusted odds ratio = 17.0; 95% CI 2.2-134.1, P = 0.007) after controlling for high-risk HPV infection and other risk factors for HSIL. Nine of 14 (63%) HSIL cases were associated with HPV-16 or HPV-18 infection, and might have been prevented by an effective HPV-16/18 vaccine.

Chapter 5: Updating the natural history of HPV and anogenital cancer

The major steps in cervical carcinogenesis include infection of the metaplastic epithelium of the cervical transformation zone with one or more of the 12-18 carcinogenic types of human papillomavirus (HPV) infection, viral persistence, clonal progression of the persistently-infected epithelium to cervical precancer, and invasion. Although these fundamental steps are established, several new epidemiologic studies have shed light on the factors that influence each of these transitions. The importance of the transformation zone in cervical cancer has been extended to other HPV-induced cancers such as anal or tonsillar cancers. Natural history studies show that HPV with normal cervical cytology and cervical intraepithelial neoplasia (CIN) grade 1 behave similarly, with the majority of both showing regression. Although these studies have demonstrated the importance of HPV persistence in the development of precancer CIN-3, the timing from infection to evidence of CIN-3 varies from 1 to 10 years. Whether equivalent lesions diagnosed later differ in their natural history remains unknown. Several factors have been implicated in enhancing persistence and/or progression. However, none are consistently associated with both except age: young women are less likely to show persistence and older women with persistence are more likely to be at risk of invasive cancer. Recent studies have also underscored the importance of the host immune response in clearance of established infections. Finally, data on non-cervical HPV infections, such as penile infections are limited to date compared to cervical infections. Several ongoing cohort studies should give us further insight into male infections in the near future.

Human papillomavirus infection in Shanxi Province, People's Republic of China: a population-based study

To investigate the prevalence of, and risk factors for, cervical infection with human papillomavirus (HPV) in the rural province of Shanxi, People's Republic of China, which has relatively high cervical cancer mortality rates, we interviewed and obtained cervical cell samples from 662 women aged 15–59 years. A total of 24 different HPV types were identified using a GP5+/6+-based PCR assay able to detect 44 different HPV types. Human papillomavirus prevalence was 14.8% overall and 9.6% among women without cervical abnormalities (14.2 and 8.9%, respectively, age standardised to the world standard population). Multiple-type infections accounted for 30.6% of all infections. By far the most commonly found type was HPV16 (5.7% of all women and 38.8% of HPV-positive women), followed by HPV 58, 52, 33 and 18. Unlike most previous studies published, HPV prevalence was lower among women younger than 35 years (8.7%) than those older than 35 years (17.8%). High-risk HPV types predominated in all age groups. Although low-risk HPV types were rare in young women, they became more common with increasing age. 92.3% of women with cervical intraepithelial neoplasia grade 3 were infected with high-risk HPV types, but none with low-risk types only. No significant difference in HPV positivity was observed by educational level, sexual habits, reproductive history or use of contraceptive methods in this rural low-income Chinese population.

High prevalence of genital human papillomavirus type 52 and 58 infection in women attending gynecologic practitioners in South Taiwan

BACKGROUND

We attempted to determine the prevalence of genital human papillomavirus (HPV) infection in women attending gynecologic practitioners in South Taiwan.

METHODS

The population included 4383 women aged 16-78 seeking HPV testing at primary gynecologic practitioners regardless of their cervical cytology results. HPV DNA was identified from cervical swabs using semi-nested polymerase chain reaction with MY11, MY09/HMB01, and MY11/bioGP6+ primers. Genotyping for high-risk HPV (HR-HPV) was done separately by a HR-HPV chip, which contained 13 type-specific oligonucleotides on a nylon membrane.

RESULTS

The overall HPV prevalence was 19.3% (849/4383), 11.1% (488/4383) were confirmed as HR-HPV positive. Among the women with HR-HPV infection, HPV-16 was the most prevalent type (22.1%; 108/488), followed by HPV-52 (21.3%; 104/488), and HPV-58 (19.9%; 97/488). Multiple infections were detected in 73 women (15.0%; 73/488). For women with age 30 or younger, the overall HPV and HR-HPV prevalence were 32.0% and 20.7%, respectively, which were significantly higher than those of women age older than 30 (17.2% and 9.5%, P < 0.001). More multiple infections (22.1% vs. 12.4%) were also found in women with age 30 or younger (P = 0.021). However, the relative contribution of types to the overall HR-HPV positive among different age groups remains the same.

CONCLUSIONS

Our results showed an HPV prevalence that is similar compared with worldwide levels. HPV prevalence and multiple infections rate were decreasing across the age groups. Unlike most previous studies, the relative high prevalence of HPV 52 and 58 among South Taiwan women has important implications in vaccine prophylaxis.

Preferential risk of HPV16 for squamous cell carcinoma and of HPV18 for adenocarcinoma of the cervix compared to women with normal cytology in The Netherlands

We present the type-distribution of high-risk human papillomavirus (HPV) types in women with normal cytology (n=1467), adenocarcinoma in situ (ACIS) (n=61), adenocarcinoma (n=70), and squamous cell carcinoma (SCC) (n=83). Cervical adenocarcinoma and ACIS were significantly more frequently associated with HPV18 (OR_MH 15.0; 95% CI 8.6–26.1 and 21.8; 95% CI 11.9–39.8, respectively) than normal cytology. Human papillomavirus16 was only associated with adenocarcinoma and ACIS after exclusion of HPV18-positive cases (OR_MH 6.6; 95% CI 2.8–16.0 and 9.4; 95% CI 2.8–31.2, respectively). For SCC, HPV16 prevalence was elevated (OR_MH 7.0; 95% CI 3.9–12.4) compared to cases with normal cytology, and HPV18 prevalence was only increased after exclusion of HPV16-positive cases (OR_MH 4.3; 95% CI 1.6–11.6). These results suggest that HPV18 is mainly a risk factor for the development of adenocarcinoma whereas HPV16 is associated with both SCC and adenocarcinoma.

Cervical human papillomavirus screening among older women

Rates of acquisition and clearance of cervical human papillomavirus (HPV) during a 3-year period in women 51 years of age were compared with rates in younger women to provide data on cervical screening for women >50 years of age. Paired, cytologically negative, archived cervical smears taken 3 years apart from 710 women in Nottingham, United Kingdom, were retrieved and tested for HPV infection with polymerase chain reaction (PCR) with GP5+/6+ primers. Seventy-one (21.3%) of 333 women 51 years of age who were HPV negative at baseline were positive 3 years later. This percentage was higher than the corresponding acquisition rates among women 21 (15.2%), 31 (14.1%), and 41 (13.3%) years of age, although these differences were not significant. This retrospective study shows that HPV-negative women >50 years of age can acquire HPV and, therefore, require cervical screening.

The elevated 10-year risk of cervical precancer and cancer in women with human papillomavirus (HPV) type 16 or 18 and the possible utility of type-specific HPV testing in clinical practice

BACKGROUND

Human papillomavirus (HPV) types 16 and 18 cause 60%-70% of cervical cancer worldwide, and other HPV types cause virtually all remaining cases. Pooled HPV testing for 13 oncogenic types, including HPV16 and 18, is currently used in clinical practice for triage of equivocal cytology and, in conjunction with Pap tests, is an option for general screening among women 30 years of age and older. It is not clear to what extent individual identification of HPV16 or HPV18 as an adjunct to pooled oncogenic HPV testing might effectively identify women at particularly high risk of cervical cancer or its immediate precursor, cervical intraepithelial neoplasia 3 (CIN3).

METHODS

From April 1, 1989, to November 2, 1990, a total of 20 810 women in the Kaiser Permanente health plan in Portland, OR, enrolled in a cohort study of HPV and cervical neoplasia. Women were tested for 13 oncogenic HPV types by Hybrid Capture 2 (HC2), and those women with a positive HC2 test were tested for HPV16 and 18. Enrollment Pap smear interpretation and HPV test results were linked to histologically confirmed CIN3 and cervical cancer (> or = CIN3) occurring during 10 years of cytologic follow-up. We calculated cumulative incidence rates with 95% confidence intervals for each interval up to 122 months using Kaplan-Meier methods.

RESULTS

The 10-year cumulative incidence rates of > or = CIN3 were 17.2% (95% confidence interval [CI] = 11.5% to 22.9%) among HPV16+ women and 13.6% (95% CI = 3.6% to 23.7%) among HPV18+ (HPV16-) women, but only 3.0% (95% CI = 1.9% to 4.2%) among HC2+ women negative for HPV16 or HPV18. The 10-year cumulative incidence among HC2- women was 0.8% (95% CI = 0.6% to 1.1%). A subanalysis among women 30 years of age and older with normal cytology at enrollment strengthened the observed risk differences.

CONCLUSIONS

HPV screening that distinguishes HPV16 and HPV18 from other oncogenic HPV types may identify women at the greatest risk of > or = CIN3 and may permit less aggressive management of other women with oncogenic HPV infections.

Vaccination Against Cervical Cancer: Hopes and Realities

Globally, carcinomas of the anogenital tract, in particular cervical cancer, remain some of the most common cancers in women, cervical cancer represents the second most frequent gynecological malignancy and the third leading cause of cancer-related death in women worldwide. The causal relationship between human papilomavirus (HPV) infection and anogenital cancer has prompted substantial interest in the development of both preventive and therapeutic vaccines against high-risk HPV types. In the past decade, several groups have shown encouraging results using experimental vaccination systems in animal models and these results have led to several current prophylactic and therapeutic vaccine clinical trials in humans. Prophylactic vaccination focuses on the induction of high titer neutralizing antibodies that are potentially protective against incident and persistent HPV infection. Two major phase II clinical trials conducted by pharmaceutical companies have demonstrated that their vaccines have 100% efficacy in preventing persistent viral DNA and its associated cellular abnormalities; however, whether they induce long-lasting protective immunity is yet to be determined. At least one US FDA approved prophylactic vaccine targeting the two most common high-risk HPVs is expected to be on the market within the next 2-3 years. Nevertheless, significant reductions in the frequency and onset of cytologic screening and incidences of HPV-related lesions are not expected to become apparent for decades due to the fact that there will be women who are already infected with HPV, the long latency period between infection and development of high-grade lesions, and lesions associated with other high-risk HPV types not being included in the vaccines. Therapeutic vaccines aim to control HPV-associated malignancies by stimulating cellular immune responses that target established HPV infections via viral proteins. Progress in the field of HPV immunotherapy has remained elusive, with clinical trials being limited to small numbers of patients. Potential treatment of precancerous lesions is unique to HPV-associated infection and cancer because of cytologic monitoring and HPV typing. Unlike more common surgical treatments for cervical lesions, active immunotherapy has the potential to address HPV persistence as the cause of lesion development in addition to leaving the patient with long-term immunity that can be reactivated if and when the patient becomes reinfected.