Epidemiology of HPV infection among Mexican women with normal cervical cytology

Sexual behavior, condom use, and human papillomavirus: pooled analysis of the IARC human papillomavirus prevalence surveys

Human papillomavirus (HPV) is a sexually transmitted infection but it is unclear whether differences in transmission efficacy exist between individual HPV types. Information on sexual behavior was collected from 11 areas in four continents among population-based, age-stratified random samples of women of ages > or = 15 years. HPV testing was done using PCR-based enzyme immunoassay. Unconditional logistic regression was used to estimate odds ratios (OR) of being HPV positive and corresponding 95% confidence intervals (95% CI). Variables were analyzed categorically. When more than two groups were compared, floating confidence intervals were estimated by treating ORs as floating absolute risks. A total of 11,337 women (mean age, 41.9 years) were available. We confirmed that lifetime number of sexual partners is associated with HPV positivity (OR for > or = 2 versus 1, 1.86; 95% CI, 1.63-2.11) but the association was not a linear one for HPV18, 31, and 33 (i.e., no clear increase for > or = 3 versus 2 sexual partners). Women who had multiple-type infection and high-risk HPV type infection reported a statistically nonsignificant higher number of sexual partners than women who had single-type and low-risk type infections, respectively. Early age at sexual debut was not significantly related to HPV positivity. Husband's extramarital sexual relationships were associated with an OR of 1.45 (95% CI, 1.24-1.70) for HPV positivity in their wives after adjustment for age and lifetime number of women's sexual partners. We did not observe a significant association with condom use. Our study showed an effect of both women's and their husbands' sexual behavior on HPV positivity. Furthermore, it suggests some differences in the pattern of the association between sexual behavior and different HPV types.

Distribution of HPV16 and 18 intratypic variants in normal cytology, intraepithelial lesions, and cervical cancer in a Mexican population

OBJECTIVE

Several intratype variants of HPV16 and 18 have been identified. These variants are associated with populations from different geographic regions, and show a differential distribution among the severity of the cervical lesion, most likely due to different pathogenic potential. The objective of this study was to investigate the variant distribution of HPV16 and 18 in a Mexican population and its association with the severity of the cervical lesion and the histological lineage of cervical cancer.

METHODS

HPV types 16 and 18 detection was performed in 412 samples of preinvasive and invasive specimens from patients attending a Primary Health-Care Center, an Early Cervical Lesion Clinic, or a Cancer Center. Distribution of HPV variants was correlated with the cytological findings and tumor cell types using contingency tables. Statistical difference was tested with the Fisher's Exact Test or its Fisher-Freeman-Halton extension for RXC tables. Alpha value was set at the P < 0.05.

RESULTS

Among the 277 women included in this study without cancer, 63.5% (176 cases) had a normal cytology; from the remaining 101 women, 53.5% were LSIL (54 cases), and 46.5% HSIL (47 cases). From a total of 135 invasive carcinomas, 78.5% were squamous (106 cases); 6.6% adenocarcinoma (9 cases); 9.6% adenosquamous (ADSC) (13 cases); and 5.1% were undifferentiated carcinoma (7 cases). HPV16 E and AA-a were evenly distributed among preinvasive and invasive lesions. However, the isolate AA-c was exclusively found in cervical cancer. HPV18 Var-1(E) was almost exclusively found in invasive lesions, while the HPV18 Var-2(Af) predominated in normal or preinvasive lesions. In invasive cancer, this variant was found only in squamous tumors.

CONCLUSIONS

The differential distribution of HPV16 and 18 variants in cervical lesions we found further supports experimental data on the different pathogenic potential of HPV16 and 18 variants for cervical cancer development.

Risk factors for HPV infection and cervical cancer among unscreened women in a high-risk rural area of China

We report a prevalence rate of 23.6% human papillomavirus (HPV) infection with oncogenic subtypes and 2.4% cervical intraepithelial neoplasia (CIN) III and cervical cancer (CC) in rural middle-aged women in 2 counties with the highest CC mortality in Shanxi Province, China. We examined the association of risk factors to HPV infection and to CIN III and CC in 8,798 unscreened women aged 35-50 years. Multivariate odds ratios (OR) and 95% confidence intervals (CI) for each endpoint were obtained for risk factors after adjustment for covariates. The OR of oncogenic HPV were: 1.41 (95% CI = 1.25-1.60) and 1.42 (95% CI = 1.24-1.61) for the participant and her husband having multiple sexual partners, respectively; 1.67 (95% CI = 1.37-2.04), 1.15 (95% CI = 1.04-1.26), and 0.82 (95% CI = 0.72-0.94) for ever (vs. never) diagnosed with tuberculosis, cervical inflammation and vaginal trichomoniasis, respectively; while bathing in a public (v. private) facility had an OR of 1.23 (95% CI =1.11-1.35). Seasonal fluctuations in HPV infection, but not CC, appeared in Xiangyuan County, with OR of 1.23 (95% CI = 1.14-1.33) and 1.51 (95% CI = 1.35-1.67) in Spring and Winter compared to Summer, respectively. The OR of CIN III and CC in the HPV positives were: 2.03 (95% CI = 1.63-2.53) for ages > or =45 years (vs. <40); and 4.01 (95% CI = 1.46-11.0) for > or =3 (vs. no) home births. Public health interventions and control strategies for improving the reproductive health of women in these rural populations need to be developed to reduce risk of HPV and subsequent CC.

Prevalence and determinants of human papillomavirus infection in men attending vasectomy clinics in Mexico

Large studies of genital human papillomavirus (HPV) infection in men are few and mainly include high-risk groups. We interviewed 779 men who requested a vasectomy in 27 public clinics in 14 states of Mexico. Exfoliated cells were obtained from the scrotum, the shaft of the penis, the top of the penis including the coronal sulcus, the glans and the opening of the meatus. HPV testing was performed using biotinylated L1 consensus primers and reverse line blot. Unconditional logistic regression was used to estimate odds ratios (ORs) of being HPV-positive and corresponding 95% confidence intervals (CIs). The prevalence of any type of HPV was 8.7%. HPV positivity was highest among men below age 25 (13.6%), and lowest among men aged 40 years or older (6.0%). The most commonly found HPV types were, in decreasing order, HPV59, 51, 6, 16 and 58. Lifetime number of sexual partners was associated with HPV positivity (OR for > or = 4 vs. 1 partner = 3.7, 95% CI: 2.0-6.8), mainly on account of the strong association with number of occasional and sex-worker partners. Condom use with both regular (OR = 0.4, 95% CI: 0.1-1.0) and sex-worker (OR = 0.1, 95% CI: 0.0-0.3) partners and circumcision (OR = 0.2, 95% CI: 0.1-0.4) were inversely associated with HPV positivity. HPV prevalence in Mexican men was similar to the prevalence found in Mexican women of the same age groups. The association between HPV positivity and lifetime number of sexual partners in the present low-risk male population is one of the strongest ever reported in studies in men. Condom use and circumcision were associated with a strong reduction in HPV prevalence.

Worldwide genomic diversity of the human papillomaviruses-53, 56, and 66, a group of high-risk HPVs unrelated to HPV-16 and HPV-18

Among more than 200 human papillomavirus (HPV) types presumed to exist, 18 "high-risk" HPV types are frequently found in anogenital cancer. The best studied types are HPV-16 and 18, which are only distantly related to one another and form two separate phylogenetic branches, each including six closely related types. HPV-30, 53, 56, and 66 form a third phylogenetic branch unrelated to HPV-16 and 18. Worldwide comparison of HPV-16 and 18 isolates revealed a distribution of variant genomes that correlated with the geographic origin and the ethnicity of the infected cohort and led to the concept of unique African, European, Asian, and Native American HPV-16 and 18 variants. Here, we address the question whether similar phylogenies are found for HPV-53, 56, and 66 by determining the sequence of the long control regions (LCR) of these HPVs in samples from Europe, Asia, and Africa, and from immigrant societies in North and South America. Phylogenetic trees calculated from point mutations and a few insertions/deletions affecting 2-4.2% of the nucleotide sequences were distinct for each of the three HPVs and divergent from HPV-16 and 18. In contrast to the "star-phylogenies" formed by HPV-16 and 18 variants, 44 HPV-53 isolates represented nine variants, which formed two deep dichotomic branches reminiscent of the beginning split into two new taxa, as recently observed for subtypes of HPV-44 and 68. A total of 66 HPV-56 isolates represented 17 variants, which formed three branches preferentially containing European, Asian, and African variants. Variants of a fourth branch, deeply separated from the other three, were characterized by a 25 bp insertion and created a dichotomy rather than star-like phylogeny. As it contained isolates from cohorts in all continents, it may have evolved before the spread of humans into all continents. 18 of 31 HPV-66 isolates represented the prototype clone, which was found in all parts of the world, while the remaining 13 clones formed 11 branches without any geographic association. Our findings confirm the notion of a quantitatively limited genomic diversity of each HPV type with some correlation to the geographic origin of the sample. In addition, we observed in some variants of these three HPV types mutations that affect the amino acid sequence of the E6 oncoproteins and the L1 capsid protein, supporting the possibility of immunogenic and oncogenic diversity between variants of any HPV type.

Worldwide distribution of human papillomavirus types in cytologically normal women in the International Agency for Research on Cancer HPV prevalence surveys: a pooled analysis

BACKGROUND

The proportion of women infected with human papillomavirus (HPV) varies greatly across populations, as might the distribution of HPV types. We aimed to compare HPV-type distribution in representative samples of women from different world regions.

METHODS

Women were randomly selected from the general population of 13 areas from 11 countries (Nigeria, India, Vietnam, Thailand, Korea, Colombia, Argentina, Chile, the Netherlands, Italy, and Spain). A standardised protocol was used for cervical specimen collection. All HPV testing was by GP5+/6+ PCR-based EIA. The proportion of HPV-positive women infected with different HPV types was compared by study area and between pooled regions with age-adjusted odds ratios (ORs) with corresponding 95% floating CIs.

FINDINGS

15 613 women aged 15-74 years without cytological abnormalities were included in a pooled analysis. Age-standardised HPV prevalence varied nearly 20 times between populations, from 1.4% (95% CI 0.5-2.2) in Spain to 25.6% (22.4-28.8) in Nigeria. Although both overall HPV prevalence and HPV16 prevalence were highest in sub-Saharan Africa, HPV-positive women in Europe were significantly more likely to be infected with HPV16 than were those in sub-Saharan Africa (OR 2.64, p=0.0002), and were significantly less likely to be infected with high-risk HPV types other than HPV16 (OR 0.57, p=0.004) and/or low-risk HPV types (OR 0.44. p=0.0002). Women from South America had HPV-type distribution in between those from sub-Saharan Africa and Europe. Heterogeneity between areas of Asia was significant.

INTERPRETATION

Heterogeneity in HPV type distribution among women from different populations should be taken into account when developing screening tests for the virus and predicting the effect of vaccines on the incidence of infection.

Diagnosis and management of oncogenic cervical human papillomavirus infection

Cervical HPV infection should be managed less as a typical STI and more as a strong risk factor predisposing to cervical cancer development. HPV infection is undeniably transmitted predominately through sexual contact.However, the fact that more than 80% of women followed over time will acquire at least one HR-HPV infection reflects the ubiquitous nature of the infection and the ease of transmission. Although the behavioral profiles typically associated with an increased risk for STI (including lifetime partner number, age at first intercourse, and so forth) will certainly lead to an increased risk for HPV detection, there is a high absolute prevalence of HPV even among women who have few lifetime sex partners. It could be argued that to counsel patients for an HPV infection as an STI would be counterproductive, as short of absolute abstinence, the prevention of infection is difficult and treatment options, short of excisional procedures for neoplasia, are limited. The real promise held in this area is the availability of an apparently highly effective prophylactic HPV vaccine, targeting at least HPV 16, 18, 6, and 11[33,34]. This vaccine cocktail, if it achieved 100% coverage, could theoretically prevent 50% to 70% of invasive cervical cancers and most genital warts. Vaccination will be required among women before initiation of sexual contact, presumably among girls 10 to 13 years of age. Many programmatic issues remain regarding the implementation of HPV vaccine programs, including the marketing of the vaccine as STI or cancer prevention,as reviewed in detail by Gravitt and Shah [72]. Even in the era of potentially effective vaccines, screening for cervical cancer is likely to remain a priority in cervical cancer prevention programs for at least several decades. Vaccine trials have proven high short-term efficacy; however, these effects were clearly type-specific and antibody titers gradually decrease postvaccination. It is unclear whether the protection will remain over an individual's lifetime without vaccine booster, and oncogenic HPV infections not targeted by vaccination will continue to contribute to risk for development of cervical intraepithelial neoplasia and cancer. Therefore, although the public health success of HPV vaccination is undoubtedly promising, the role of cervical cancer screening as a secondary prevention effort should not be trivialized. In fact, the nature of screening programs should continue to be reevaluated in the context of effective but limited spectrum vaccines.

Human papillomavirus infection: biology, epidemiology, and prevention

Over the past several decades, knowledge of the biology and epidemiology of human papillomavirus (HPV) infection has increased tremendously. However, there are still many unanswered questions concerning the interaction of the virus with its host. The virus has been identified as a necessary causal agent for cervical squamous neoplasia and has been linked to the development of neoplasia in several other mucosal sites. The viral oncogenes E6 and E7 are the major players in the virus' scheme to evade the immune system and use the host cell replication machinery to survive. Many risk factors for infection with HPV have been identified; however, the focus now centers on identifying risk factors for persistence of the infection as it is likely that transient infections play a very small role in the overall development of clinical disease. Prevention measures to date have centered around screening programs, mostly for cervical cancer, including the perfection of screening techniques and inclusion of molecular testing for HPV into screening regimens. The development of prophylactic and therapeutic vaccines has also increased as primary prevention measures appear to have the best hope for long-term effects on cancer incidence.

Molecular diagnosis of human papillomavirus (HPV) infections

Human papillomaviruses (HPVs) comprise more than 100 genotypes. The mucosal types can be divided into high-risk and low-risk (LR) types depending on the associated disease risk. HPV infection is mainly diagnosed by molecular methods, since reliable serological tools are not available and culture of the virus is not possible. Accurate molecular diagnostic techniques that can be used to inform patient management and follow-up after treatment are now available for detection and identification of HPV. The diagnosis of HPV infections in patients at risk of disease in a clinical setting requires a different approach from that used for epidemiological studies, vaccination trials and natural history studies. This review describes the different molecular methods available for HPV detection and genotyping and their possible clinical utility.

Determinants of Prevalence, Acquisition, and Persistence of Human Papillomavirus in Healthy Mexican Military Men

BACKGROUND

Human papillomavirus (HPV) infection is sexually transmitted, but the nature of the infection in males is poorly understood. We sought to identify determinants of HPV infection, acquisition, and persistence in 1,030 healthy military men in Mexico.

METHODS

From July 2000 to July 2003, trained interviewers administered a questionnaire, conducted a genital examination, and collected samples. The presence of multiple HPV types in genital cells from the urethra, urethral meatus, scrotum, penile shaft, and coronal sulcus was evaluated. At baseline 1,030 participants and after 1-year follow-up 336 individuals were sampled using a highly sensitive DNA reverse blot strip assay.

RESULTS

HPV prevalence was 44.6%; infection with high-risk types was observed in 34.8% participants and 51.1% were multiply infected. After 1-year follow-up, 165 men remained free of HPV, 68 cleared their infection, 45 acquired one, and 37 remained infected with the same HPV type. The period prevalence was 50.9%, the incidence rate was 17.9/1,000 men-months [95% confidence interval (95% CI), 13.0-23.9], clearance was 54%, and persistence was 29.4%. At baseline, the number of partners before age 20 years, a history of a sexually transmitted disease, and the presence of condilomas significantly increased the association with HPV infection. Having anal intercourse with males was associated with the risk of acquiring a HPV infection (odds ratio, 5.2; 95% CI, 1.2-23). The odds ratio for persistent infection was 0.10 (95% CI, 0-0.87) in men who reported being circumcised compared with those who did not.

CONCLUSIONS

High-risk sexual behavior increases the risk of HPV infection in males, whereas circumcision may lower the risk of persistence.

Human papillomavirus and abnormal Pap test results in Vietnamese-American women: a pilot case-control study

OBJECTIVE

To evaluate the relationship between abnormal Pap test results and human papillomavirus (HPV) in Vietnamese-American women, who have the highest cervical cancer incidence in the United States.

MATERIALS AND METHODS

In 2001, we obtained specimens from 117 Vietnamese women, 24 with abnormal Pap test results including atypical squamous cells of undetermined significance (cases) and 93 with normal Pap test results (controls), as classified by the 1991 Bethesda System. We used L1 consensus primers MY09/MY11 to perform HPV polymerase chain reaction analysis and type-specific probes to perform genotyping.

RESULTS

Thirteen cases (54%) and 6 controls (6%) were HPV positive (p < .001). Ten of 24 cases (42%) and 0 controls (0%) had high-risk HPV types (16, 18, 45, 53, 56, or 66; p < .001). High-risk HPV types were significantly associated with increasing severity of Pap test results.

CONCLUSIONS

Compared with those with normal Pap test results, Vietnamese-American women with abnormal Pap test results were more likely to have high-risk HPV types. Higher cervical cancer incidence among these women is likely the result of less frequent Pap screening rates and not different biology.

Human papilloma virus in oral squamous cell carcinoma in a Mexican population

OBJECTIVE

To determine the human papilloma virus (HPV) infection in oral cancer and its association with smoking and drinking habits.

STUDY DESIGN

A cross-sectional study was performed; samples were collected from 51 patients with histological diagnosis of squamous-cell carcinoma were collected at the Instituto Nacional de Cancerología in Mexico City. HPV infection was detected by polymerase chain reaction, and the clinical characteristics of this population were analyzed.

RESULTS

Fifty samples out of 51 were positive for beta-globin; 21 (42%) cases were HPV-positive, and 14/21 were positive for HPV-16. We found more samples positive in men than in women (71% vs 29%). No differences were observed between HPV-positive and -negative patients in relation to smoking and drinking habits (81% vs 79%).

CONCLUSIONS

HPV infection was present in 42% of patients with oral squamous-cell carcinoma (OSCC); HPV-16 was the most frequent type, identified in 66.6%. Other cofactors participate in the development of OSCC, independent of HPV infection.

Age-related performance of human papillomavirus testing used as an adjunct to cytology for cervical carcinoma screening in a population with a low incidence of cervical carcinoma

BACKGROUND

High-risk human papillomavirus (HR-HPV) testing has been proposed as a replacement for cytology or as an adjunct to cytology for primary cervical carcinoma screening. The objective of this study was to assess the age-specific prevalence of HR-HPV infection and the correlation between HR-HPV status and cytologic diagnosis.

METHODS

The authors enrolled 7254 women receiving routine cytologic screening in a cross-sectional study that was conducted during 12 months. Cervical samples were collected using liquid-based cytology to perform both Papanicolaou smears and HR-HPV testing. Analyses were performed using age stratification, and the cytologic results were considered as the reference diagnosis for parameter analysis tests.

RESULTS

The overall rate of HR-HPV infection was 11.4% (95% confidence interval, 9-12%) and was higher in younger women compared with older women (age < 30 years vs. > or = 30 years; 16% vs. 8.5%, respectively; P < 0.0001). The overall rate of abnormal cytology was 3.2% and, similarly, was more prevalent in younger women (6.1% vs. 2.4%; P < 0.0001). The best balance between sensitivity and specificity for high-grade lesions or worse occurred predominantly in older age groups (age > or = 50 years).

CONCLUSIONS

The prevalence of HR-HPV was age-dependent, with the strongest correlation between HR-HPV positivity and disease observed among older women, who potentially may derive the most benefit.

Epidemiologic correlates of cervical human papillomavirus prevalence in women with abnormal Pap smear tests: A Taiwan cooperative oncology group (TCOG) study

To explore factors affecting human papillomavirus (HPV) prevalence in all grades of cervical neoplasia among Chinese women, 1,264 women with abnormal cervical cytology attending the gynaecologic clinics of 11 major medical centres in Taiwan. Patients were interviewed and underwent complete gynaecologic examination including colposcopy. Cervical scrapings were collected for HPV DNA detection by both Hybrid Capture-2 (high-risk probe) and L1 consensus PCR-reverse line blot. The prevalences of HPV in the four different diagnosis groups: (i) suspicious (n = 316), (ii) low-grade intraepithelial lesion (n = 474), (iii) high-grade intraepithelial lesion (n = 450), and (iv) cancer (n = 16), were 36.1%, 74.7%, 83.6%, and 100%, respectively. In the latter two groups, Patients less than 30 or 40 years old, respectively, tended to be infected more frequently with HPV than the older patients were. The main correlates of HPV prevalence were lifetime number of sex partners (odds ratio (OR) for two or more partners: 2.44; 95% CI, 1.44-4.15), vaginal douching after intercourse (OR for douching frequently: 1.44; 95% CI, 1.01-2.04), vitamin supplementation (OR for regular vitamin supplement: 0.71, 95% CI, 0.55-0.92), and performance of Pap smear tests (OR for never having a Pap smear performed: 2.22; 95% CI, 1.19-4.17). The risk for vaginal douching was augmented by the promiscuity of sex partners (OR of 3.19 (1.91-5.34)) and smoking (OR of 1.90 (1.15-3.13)), whereas vitamin supplementation reduced the odds ratio to 1.35 (0.85-2.15). The results of this study provide further evidence of the role of HPV in cervical carcinogenesis. The data also indicate the main areas of risk for the prevalence of HPV in cervical neoplasia in Chinese women living in Taiwan.

The IARC commitment to cancer prevention: the example of papillomavirus and cervical cancer

Every year approximately half a million women worldwide develop cervical cancer (CC) of whom 80% live in poor countries where population-based screening programmes are virtually non-existent. The role of sexually transmitted agents in the aetiology of cervical cancer has been suspected for more than a century, but knowledge in this field has rapidly expanded only in the last 20 years, after major improvements were made in detection methods for human papillomavirus (HPV). A dozen types of HPV have been identified in 99% of biopsy specimens from CC worldwide and the relative risk estimates for HPV in case-control studies of CC are in the 50 to 100 range. A meta-analysis done at the International Agency for Research on Cancer (IARC) included a total of 10,058 CC cases from 85 published studies. The most common HPV types identified in CC were, in order of decreasing prevalence, HPV 16, 18, 45, 31, 33, 58, 52, 35, 59, 56, 6, 51, 68, 39, 82, 73, 66 and 70. Over two-thirds of CC cases were associated with an infection of either HPV 16 (51.0%) or HPV 18 (16.2%). Despite the overwhelming importance of HPV, other factors contribute to the rare occurrence of CC after HPV infection. Nine case-control studies from the IARC have confirmed the adverse effect of long-term use of oral contraceptives, high parity, smoking and sexually transmitted infections (i.e. Chlamydia trachomatis and herpes simplex virus-2) after adjustment for, or stratification by, HPV infection. Ten surveys of HPV infection in population-based samples of approximately 15,000 women in four continents have shown that: (1) the prevalence of HPV infection varies greatly (between 2% and nearly 30%); and (2) the age distribution also varies widely, pointing to cohort effects. There is no effective medical treatment for HPV, but a prophylactic vaccine, based on late (L) 1 HPV 16 proteins, has been shown to be safe, highly immunogenic and efficacious in preventing persistent HPV infections. A multivalent vaccine against the most common oncogenic HPV types may thus ultimately represent the most effective way to prevent CC worldwide either alone, or in combination with screening. It may, however, take several years before this approach becomes a reality. Thus, early detection of CC precursor lesions by screening, and their treatment, will remain the most important measures for the control of CC for the foreseeable future.

A cost-effectiveness analysis of four management strategies in the determination and follow-up of atypical squamous cells of undetermined significance

Atypical squamous cells of undetermined significance (ASC-US) are the most common abnormal cytological result on Papanicolaou (Pap) smear. We analyzed four management strategies in a hypothetical cohort of women divided by age group: (1) immediate colposcopy, (2) repeat cytology after an ASC-US Pap smear result, (3) conventional Pap with reflex human papillomavirus (HPV) testing, and (4) liquid-based cytology with reflex HPV testing. Parameter variables were collected from previously published data. Strategies that included reflex HPV testing had the lowest overall costs for all age groups combined. Repeat Pap smears had the highest number of true positive results throughout all stages but also had the uppermost number of missed cancers and highest costs. Immediate colposcopy had the second highest overall costs and detected fewer true positive results than liquid-based cytology. Younger women (aged 18-24 yr) consistently had higher total costs for all strategies investigated. Using the incremental cost-effectiveness (CE) ratio, the immediate colposcopy strategy was more costly and less effective than liquid-based cytology and, therefore, was dominated. The incremental CE ratio was lowest for liquid-based cytology compared with conventional cytology and liquid-based cytology with reflex HPV testing was the most cost-effective strategy.

Prevalence of human papillomavirus infection in women in Turin, Italy

Human papillomavirus (HPV) is recognised as necessary for the development of cervical cancer. An age-stratified random sample of 1013 women, aged 25-70 years, participating in the organised cervical screening programme in Turin, Italy was tested for 36 HPV types using polymerase chain reaction (PCR) with the general primers GP5+/GP6+. The overall HPV prevalence was 8.8%. High-risk types were found in 7.1% of women and multiple infections in 1.1%. HPV-16 was the most common type (32.6% of HPV-positive women). HPV prevalence (any type) was 13-14% at ages 25-39 years, 11.5% at age 40-44 years, and approximately 5% among older women. After age-adjustment, HPV prevalence was significantly increased in single vs married, (Odds Ratio (OR)=2.23; 95% Confidence Interval (CI): 1.28-3.89) and decreased in parous vs nulliparous women (OR=0.49; 95% CI: 0.31-0.78). However, the association with marital status and parity was restricted to women less than 45 years of age. In conclusion, overall, the female population of Turin showed an HPV prevalence that is intermediate compared with worldwide levels.

Human papillomavirus infection and P53 codon 72 genotypes in a hispanic population at high-risk for cervical cancer

Cervical cancer mortality is high in Texas, especially among Hispanic women living in south Texas and adjacent Mexico. Though human papillomavirus (HPV) infection has a causal role in the development of cervical cancer, there are no published data on the prevalence of HPV genotypes in this underscreened region. We studied 398 Hispanic women on both sides of the border along the lower Rio Grande River to determine the prevalence of HPV genotypes and risk factors for cervical cancer. Using a nested PCR system HPV was detected in 62% of cervical specimens, including all the known high-risk HPV genotypes, with HPV16 and HPV18 the most frequent (30.6% and 23.0%, respectively). Multiple infections were common (29.4% of the infected specimens), and where this occurred we were more likely to find high-risk HPV genotypes. We examined host p53 codon 72 genotype frequencies and found that patients with cervical abnormalities and women with HPV16 and HPV18 infections had a lower genotype frequency of the homozygous (AA) previously reported to be associated with cervical cancer, than uninfected women with no abnormalities. In this US/Mexico border population high rates of potentially oncogenic HPV viruses and multiple infections are consistent with observed elevated cervical cancer rates. These data are further evidence that in this underserved population HPV infections are associated with high rates of malignancy, but that host p53 genotypic variations are unlikely to be primary factors in oncogenesis.

Noncorrelating Pap tests and cervical biopsies: Histological predictors of subsequent correlation

Lack of correlation between dysplastic cervicovaginal Papanicolaou (Pap) tests and subsequent cervical biopsies raises the concern that a significant squamous intraepithelial lesion (SIL) may go unconfirmed. Additional tissue sections of cervical biopsies may detect SILs after noncorrelation on initial sections. Complete step sectioning of paraffin blocks was undertaken on 111 noncorrelating biopsy specimens from 95 patients and selected slides were reviewed for the presence of SIL. The initial negative biopsy slides were evaluated for four histological features: chronic cervicitis, acute cervicitis, mucosal erosion, and squamous atypia. Twenty-seven biopsies (24.3%) demonstrated the presence of a SIL in deeper levels. The presence of squamous atypia was significantly associated with the presence of dysplasia deeper in the block (P < 0.002). Acute and chronic cervicitis was seen roughly equally. Additional tissue levels are a productive way of confirming SILs, and squamous atypia allows a refined selection of negative cervical biopsies most likely to reveal an SIL on review of deeper levels.

Detection and genotyping of human papillomavirus in cervical samples from Italian patients

Human papillomaviruses (HPVs) are etiological agents of cervical cancer. In order to assess the epidemiological incidence and frequency of different HPV types, we applied a polymerase chain reaction (PCR)-direct sequencing approach based on the use of MY09/MY11 primers as compared to Hybrid Capture assay. Cervical samples were taken from 1,500 women, both with normal and abnormal cytological smears, and we found an incidence of 6.6% of HPV infection in Brescia. Overall, 97 samples tested HPV-positive, yielding 18 HPV types. The four most frequent HPV types were: HPV 16, -31, -6, and -58. This approach could be used in ordinary laboratory settings for quick and reliable typing of known and novel HPVs from clinical specimens and it could also be applied to anti-cancer vaccine development.

Population-Based Prevalence and Age Distribution of Human Papillomavirus Among Women in Santiago, Chile

More than 18 types of human papillomavirus (HPV) are associated with cervical cancer, the relative importance of the HPV types may vary in different populations.

Objective: To investigate the types of HPV, age distribution, and risk factors for HPV infection in women from Santiago, Chile.

Methods: We interviewed and obtained two cervical specimens from a population-based random sample of 1,038 sexually active women (age range, 15-69 years). Specimens were tested for the presence of HPV DNA using a GP5+/6+ primer-mediated PCR and for cervical cytologic abnormalities by Papanicolaou smears.

Results: 122 women tested positive for HPV DNA, 87 with high risk types (HR), and 35 with low risks (LR) only. Standardized prevalence of HPV DNA was 14.0% [95% confidence interval (95% CI), 11.5-16.4]. HR HPV by age showed a J reverse curve, whereas LR HPV showed a U curve, both statistically significant in comparison with no effect or with a linear effect. We found 34 HPV types (13 HR and 21 LR); HPV 16, 56, 31, 58, 59, 18, and 52 accounted for 75.4% of HR infections. Thirty-four (3.6%) women had cytologic lesions. Main risk factor for HPV and for cytologic abnormalities was number of lifetime sexual partners, odds ratios for ≥3 versus 1 were 2.8 (95% CI, 1.6-5.0) and 3.8 (95% CI, 1.3-11.4), respectively.

Conclusions: LR HPV presented a clear bimodal age pattern; HR HPV presented a J reverse curve. HPV prevalence was similar to that described in most Latin American countries.

Human papillomavirus infection and cervical ectopy

OBJECTIVES

To investigate the prevalence of human papillomavirus (HPV), and HPV type 16 (HPV16) infection in cervical ectopy, and the presence of anti-HPV16 secretory IgA (sIgA) antibodies.

METHODS

DNA from patients with cervical ectopy (n=218), HPV-associated lesions (n=111), and controls without evidence of cervical ectopy or HPV infection (n=93) were analyzed by PCR for the presence of HPV and HPV16. The presence of mucosal sIgA antibodies against HPV16 capsid antigens (VLP) was assayed in cervical mucus by ELISA.

RESULTS

Prevalence of HPV DNA was higher in cervical ectopy than in controls (P=0.04; OR=2.06; 95% CI 0.99-4.33). HPV16 was 6.3 times more prevalent in cervical ectopy than in controls. Anti-HPV16 sIgA were detected more frequently in cervical ectopy patients than in controls (P=0.0004).

CONCLUSIONS

Cervical ectopy correlates with HPV infection. HPV16 is highly prevalent in cervical ectopy. sIgA antibodies against HPV16 capsids are generated in patients with cervical ectopy.

Human papillomavirus and cervical cancer: issues for biobehavioral and psychosocial research

There is now overwhelming evidence that high-risk, sexually transmitted types of human papillomavirus (HPV) are the main causal agent in cervical cancer. Biobehavioral and psychosocial research is uniquely capable of addressing many of the issues raised by HPV and its link with cervical cancer. In this article we review current findings in this area and identify issues for future research. The first of the three sections explores issues associated with the introduction of HPV testing for the detection and management of cervical abnormalities and the impact of growing public awareness of the sexually transmitted nature of cervical cancer. The implications for public understanding of cervical cancer, psychosocial issues associated with screening, and the potential impact on screening uptake are discussed. The second section addresses the role of biobehavioral factors in the persistence and progression of HPV infection as well as possible interventions to minimize the risk of persistence. Finally, primary prevention of HPV is discussed.

Low prevalence of HPV infection and its natural history in normal oral mucosa among volunteers on Miyako Island, Japan

OBJECTIVE

To investigate the prevalence of human papillomavirus (HPV) infection in normal oral mucosa, and to observe the natural history in the oral cavity in oral swab samples collected from healthy volunteers on Miyako Island, Okinawa, Japan.

STUDY DESIGN

The prevalence of HPV infection in oral buccal mucosa cell scrapes collected between 2000 and 2002 from a cohort of 668 healthy volunteers was determined. HPV DNA was detected by consensus polymerase chain reaction (PCR) using MY09/MY11 primers followed by direct cycle sequencing. Just over 2 years later the HPV-positive participants were reevaluated.

RESULTS

Of the 668 subjects, 662 samples were analyzed for HPV. HPV DNA was detected in 4 (0.6%) specimens. HPV type 16 (HPV16), HPV53, and HPV71, mucosal types, and HPV12, a cutaneous type, were all identified by direct sequencing. In the follow-up survey, the HPV71- and HPV12-positive participants again tested positive, while HPV DNA was not detected in the HPV16- and HPV53-positive participants.

CONCLUSION

The results of this study among healthy individuals from Miyako Island suggest that oral HPV infection is uncommon. In this cohort, HPV71 and HPV12 were persistent, while HPV16 and HPV53 were transient in normal oral mucosa.

Human papillomavirus typing of rare cervical carcinomas

CONTEXT

Most cervical tumors are classified as squamous cell carcinoma or adenocarcinoma, both of which are associated with persistent human papillomavirus (HPV) infection. Although other (rare) types represent less than 5% of all cervical carcinomas, it is necessary that these more unusual tumors be studied in the current era of papillomavirus vaccine development, especially in regions with high incidence of cervical cancer.

OBJECTIVE

To compare papillomavirus types found in histologically rare cervical carcinomas (n = 29) with those types found in common cervical carcinomas (n = 14) archived at the Institute of Cancer in Mexico City, Mexico.

DESIGN

Paraffin-embedded tissues were received and sectioned at the Louisiana State University Health Sciences Center at Shreveport. One section for each block was stained and examined by 2 pathologists. Specific histologies were categorized into 2 broad groups: common (squamous cell carcinoma or adenocarcinoma) or rare (adenosquamous, papillary, villoglandular, anaplastic, transitional, spindle, adenoid basal, colloid, neuroendocrine, and glassy cell carcinomas). Papillomavirus typing results were based on Roche Molecular Systems line-blot assay.

RESULTS

No significant difference was found for dual HPV types (21% of both groups), positivity for HPV-16 (66% of rare tumors and 71% of common tumors), or absence of HPV types 16 or 18, although the rare cancers had a greater tendency toward more unusual HPV types (8/29 rare tumors and 1/14 common tumors had no HPV- 16 or HPV-18 DNA). Non-HPV-16/18 types found only in rare tumors included HPV types 52, 84, 26, 35, and 58.

CONCLUSIONS

Rare types of cervical carcinoma also are associated with papillomavirus, most with types similar to those found in common cervical neoplasias.

Levels and correlates of knowledge about cancer risk factors among 13,293 public school students in Morelos, Mexico

BACKGROUND

Data on young people's knowledge about cancer prevention are not currently available for many populations, including Mexican young people, although cancer is the second most common cause of death among the Mexican population.

METHODS

A questionnaire was applied to 13,293 public school students aged 11-24 years in Morelos, Mexico. A knowledge-based scale was constructed from survey answers about risk factors for cancer. Data were analyzed using multivariate logistic multinomial models.

RESULTS

Knowledge levels were low: 78% of male and 74% of female students had only wrong answers to questions about risk factors for cancer. A significant dose-response gradient was observed between age and knowledge of cancer risk factors (P < 0.001), with a higher prevalence in young women at all ages (female students OR 4.6, 95% CI 3.81-5.66). Students 18 years old and older knew more than 13-year-olds (OR = 2.39; 95% CI 1.89-3.01). Sexually active students (OR 2.10; 95% CI 1.70-2.58), especially those who consistently used condoms (OR 2.84; 95% CI 1.00-8.07), knew more about cancer prevention. Tobacco smoking was the most frequently recognized cancer risk factor, and smokers also recognized this as an important cause of cancer (OR 1.37; 95% CI 1.44-2.52).

CONCLUSIONS

Our results reveal a poor level of knowledge about cancer prevention among adolescents. These data are the first step in the development of an intervention based on empirical findings that will be susceptible to evaluation.

[Epidemiology of HPV infection]

HPV DNA testing using Hybrid Capture 2 (Digene) was added to a program of liquid based (Thinprep, Cytyc) cervical cancer screening in a population of sexually active women aged from 20 to 62 years, without the history of uterine cervix pathology. 14.32% of 3832 women in this population were HPV positive. Positivity peaked in women aged 25-29 (19.4%) and gradually decreased, with 8% of positivity after 60 years. Positivity was independently related to parity, tobacco use and was correlated to cervical pathology. The rate of positivity in this population seems to preclude the use of HPV testing as a primary screening tool.

Prevalence of papillomavirus infection in women in Ibadan, Nigeria: a population-based study

To investigate the prevalence of and the risk factors for cervical infection with human papillomavirus (HPV) in an inner-city area of Ibadan, Nigeria, we interviewed and obtained a sample of cervical cells from 932 sexually active women aged 15 years or older. A total of 32 different HPV types were identified with an HPV prevalence of 26.3% overall and 24.8% among women without cervical lesions; or age-standardised to the world standard population of 28.3 and 27.3%, respectively. High-risk HPV types predominated, most notably HPV 16, 31, 35 and 58. In all, 33.5% of infections involved more than one HPV type. Unlike most populations studied so far, HPV prevalence was high not only among young women, but also in middle and old age. Single women (odds ratio, OR=2.1; 95% confidence interval, CI=1.1–3.9) and illiterate women (OR=1.7; 95%CI=1.1–2.5) showed increased HPV positivity. Associations were also found with anti-Herpes simplex-2 antibodies (OR=1.6; 95% CI: 1.1–2.1) and with the husband's extramarital relationships (OR=1.6: 95% CI: 1.0–2.6). High prevalence of HPV in all age groups may be a distinctive feature of populations where HPV transmission continues into middle age and cervical cancer incidence is very high.

Human population-based identification of CD4(+) T-cell peptide epitope determinants

A human cell-based method to identify functional CD4(+) T-cell epitopes in any protein has been developed. Proteins are tested as synthetic 15-mer peptides offset by three amino acids. Percent responses within a large donor population are tabulated for each peptide in the set. Peptide epitope regions are designated by difference in response frequency from the overall background response rate for the compiled dataset. Epitope peptide responses are reproducible, with a median coefficient of variance of 21% when tested on multiple random-donor sets. The overall average response rate within the dataset increases with increasing putative human population antigenic exposure to a given protein. The background rate was high for HPV16 E6, and was low for human-derived cytokine proteins. The assay identified recall epitope regions within the donor population for the protein staphylokinase. For an industrial protease with minimal presumed population exposure, immunodominant epitope peptides were identified that were found to bind promiscuously to many HLA class II molecules in vitro. The peptide epitope regions identified in presumably unexposed donors represent a subset of the total recall epitopes. Finally, as a negative control, the assay found no peptide epitope regions in human beta2-microglobulin. This method identifies functional CD4(+) T-cell epitopes in any protein without pre-selection for HLA class II, suggests whether a donor population is pre-exposed to a protein of interest, and does not require sensitized donors for in vitro testing.

Chapter 1: Human papillomavirus and cervical cancer--burden and assessment of causality

Cervical cancer remains the second most common cancer in women worldwide and the most frequent in developing countries. Pre-neoplasic cervical lesions represent an additional burden in countries where screening is widespread. The human papillomavirus (HPV) prevalence and type distribution in normal smears and in cancer specimens are being described and show relatively small international variation. State-of-the-art detection techniques have unequivocally shown that HPV-DNA can be detected in 95% to 100% of adequate specimens of cervical cancer, supporting the claim that HPV is the necessary cause. The odds ratios for cervical cancer related to a cross sectional detection of HPV-DNA range from 50 to several hundred in all studies. The risk for any of 15 high-risk types is not statistically different from the risk reported for HPV16. The estimates of the attributable fraction range from 90% to 98%. Additional work should be done in providing information on incidence of cervical cancer and on HPV infection in areas where the disease is common. Theoretical work including modeling of the incidence could be of potential use in the evaluation of the existing and novel preventive strategies. Research is currently being conducted on the mechanisms of HPV carcinogenesis. These include the determinants of the systemic and cellular immune response to the viral infection, the interaction between the host and the virus and the relevance of the different strains and variants of the HPV viral types. Technology developments in this area suitable for epidemiological studies are needed.

Cervical cytological screening and human papillomavirus DNA testing in Flanders

The causal relationship between genital human papillomavirus (HPV) infection and cervical dysplasia/carcinoma has been recognised for some time. The aim of this study was to document the occurrence and distribution of HPV infection in the five provinces of the Flemish region in Belgium and to correlate the HPV DNA test results with the cytological results on simultaneously performed thin layer preparations of cervical cells. Out of a total screened group of 105107 samples, 1978 samples with cytological abnormalities were tested for HPV DNA using the MY09/MY11 consensus PCR. The mean age of the whole group was 36.9 years. The LSIL group, with a mean age of 33.6 years, was significantly younger than the other groups. There was no significant difference in HPV prevalence among the provinces. In four out of five provinces the HPV prevalence reached 100% in high-grade lesions. There is a significant increase in predominance of high-risk HPV types, with increasing abnormal cytology (17.9% WNL < 51.1% ASCUS < 83.8% LSIL < 97.2% HSIL). Three peaks of HPV DNA positivity were observed, a first at 22 yrs (82%), a second at 47 yrs (60%) and a third in women older than 65 yrs (52%). These results shed more light on HPV prevalence in Flanders and show that the MY09/MY11 consensus primer based detection system is very suitable for the detection of HPV infections in Flanders.

Human papillomavirus infection and use of oral contraceptives

Human papillomavirus (HPV) infection is thought to be a necessary but not sufficient cause of most cases of cervical cancer. Since oral contraceptive use for long durations is associated with an increased risk of cervical cancer, it is important to know whether HPV infection is more common in oral contraceptive users. We present a systematic review of 19 epidemiological studies of the risk of genital HPV infection and oral contraceptive use. There was no evidence for a strong positive or negative association between HPV positivity and ever use or long duration use of oral contraceptives. The limited data available, the presence of heterogeneity between studies and the possibility of bias and confounding mean, however, that these results must be interpreted cautiously. Further studies are needed to confirm these findings and to investigate possible relations between oral contraceptive use and the persistence and detectability of cervical HPV infection.

Prevalence of human papillomavirus infection in rural villages of the Bolivian Amazon

Cervical cancer constitutes a major health problem in developing countries like Bolivia. The roles of certain genotypes of human papillomaviruses (HPVs) in the pathogenesis of cervical cancer is well established. The prevalence of HPV infection among sexually active women varies greatly. Information regarding HPV infection in Bolivia is very much scarce, specially in regions like the Amazonian lowland. We studied 135 healthy women living in four rural localities of the Bolivian Amazon. Presence of HPV in DNA extracted from cervical swabs was analyzed using a reverse line hybridization assay. The estimated overall HPV infection prevalence among the studied rural localities was 5.9% (ranging from 0-16.6%). These values were unexpectedly low considering Bolivia has a high incidence of cervical cancer. The fact that Amazonian people seem to be less exposed to HPV, makes it likely that some other risk factors including host lifestyle behaviors and genetic background may be involved in the development of cervical cancer in this population.

Human papillomavirus infection among women in South and North Vietnam

The incidence rate of invasive cervical carcinoma (ICC) is 4-fold higher in Ho Chi Minh City, in the South of Vietnam, than in Hanoi, in the North. Thus, we explored the prevalence of and the risk factors for human papillomavirus (HPV) infection in these 2 areas. A population-based random sample of married women aged 15-69 years were interviewed and had a gynaecological examination in the urban district of Ho Chi Minh City and in a peri-urban district in Hanoi. HPV DNA detection was performed using a GP5+/6+ primer-mediated PCR enzyme immunoassay. A total of 922 women from Ho Chi Minh and 994 from Hanoi, for whom a Pap smear and HPV-status were available, were evaluated. HPV DNA was detected among 10.9% of women in Ho Chi Minh City and 2.0% in Hanoi (age standardized prevalence, world standard population: 10.6% and 2.3%, respectively). In the 2 areas combined, 30 different HPV types were found, the most common being HPV 16 (in 14 single and 18 multiple infections), followed by HPV 58, 18 and 56. A peak of HPV DNA detection in women younger than age 25 was found in Ho Chi Minh City (22.3%) but not in Hanoi. Major risk factors for HPV DNA detection were indicators of sexual habits, most notably the presence of HSV-2 antibodies, nulliparity and the current use of oral contraceptives. Women in Hanoi showed the lowest HPV prevalence ever reported so far, suggesting that HPV has not spread widely in this population. As expected, HPV prevalence in a population seemed to be closely correlated with ICC incidence rates.

Prevalence of specific types of human papillomavirus and cervical squamous intraepithelial lesions in consecutive, previously unscreened, West-African women over 35 years of age

Previous studies among women worldwide have demonstrated that infection with specific types of human papillomaviruses (HPV) is central to the pathogenesis of cervical neoplasia. There is little data, however, concerning the prevalence of specific HPV types and the association of each type with cervical neoplasia among women in sub-Saharan Africa, who remain at very high risk of cervical cancer. We studied 2,065 consecutive patients aged 35 years or older, presenting to community health clinics in Dakar and Pikine, West Africa, who had not been screened previously for cytologic abnormalities or HPV. Cytologic diagnosis and HPV detection were accomplished using a ThinPrep Pap and a polymerase chain reaction-based reverse-line strip assay, respectively. Odds ratios (OR) and associated 95% confidence intervals (CI) were estimated using polynomial logistic regression. Cytologic abnormalities were found in 426 women (20%), including 254 (12%) with atypical squamous cells of undetermined significance, 86 (4%) with low-grade squamous intraepithelial lesions, 66 (3%) with high-grade squamous intraepithelial lesions (HSIL) and 20 (1%) with invasive cancer. HPV infection was detected in 18%. Among women with negative cytologic findings, the prevalence of high risk but not low risk HPV types increased with age. HPV16 (2.4%) and HPV58 (1.6%) were the most frequently detected HPV types in this population, as well as being the most strongly associated with risk of HSIL/cancer (HPV16: OR = 88, 95% CI = 39-200; HPV58: OR = 51, 95% CI = 16-161). These data suggest that in addition to HPV16, HPV58 should be considered in the strategic planning of vaccination against cervical cancer in this geographic region.

Prevalence of human papillomavirus infection in women in Busan, South Korea

To investigate the prevalence of and the risk factors for human papillomavirus (HPV) infection in South Korea, we interviewed and examined a randomly selected sample of 863 sexually active women (age range = 20-74 years, median 44) and 103 self-reported virgins from Busan. The presence of DNA of 34 different HPV types in cervical exfoliated cells was tested among sexually active women by means of a PCR-based assay. IgG antibodies against L1 virus-like particles (anti-VLPs) of HPV types 16, 18, 31, 33 and 58 were also evaluated by means of ELISA. The overall prevalence of HPV DNA was 10.4% (95% confidence interval, CI: 8.5-12.7%). The most often found HPV DNA types were HPV 70, HPV 16 and HPV 33; 19.8% (95% CI: 17.2-22.0) of sexually active women had antibodies against one or more HPV types. The most common anti-VLPs were against HPV 18, 31 and 16. Prevalences standardized by age on the basis of the world standard population were 13.0% for HPV DNA and 17.1% for anti-VLPs. The concordance between the 2 HPV markers at an individual level was modest, but the risk factors for detection of HPV DNA and anti-VLPs were similar: number of lifetime sexual partners (odds ratio, OR for >/= 4 vs. 1 = 3.5 and 5.4, respectively), seropositivity for herpes simplex virus-2 antibodies (OR = 2.6 and 2.5, respectively) and being single or divorced. HPV DNA, but not anti-VLPs, were elevated among women whose husbands were thought by their wives to have extra-marital affairs and those who had undergone vasectomy. Among 103 virgins, 4.9% had anti-VLPs (1/73 among those aged 24 years or less).

Low grade squamous intra-epithelial lesions and human papillomavirus infection in Colombian women

Low grade squamous intra-epithelial lesions could be considered as a manifestation of human papillomavirus exposition, however the discrepancy between rates of infection with human papillomavirus and development of low grade squamous intra-epithelial lesions is notable. Here we report a cross-sectional three-armed case-control study in the Colombian population, to compare the risk factors of women with low grade squamous intra-epithelial lesions with that of human papillomavirus DNA-negative and positive women with normal cytology.

Strategies for HPV prevention

The HPV types that cause cervical cancer are sexually transmitted, but there is little evidence that infection can be avoided by behavioral change, such as condom use. In contrast, prophylactic vaccines against HPV infection are likely to have high efficacy. In principle, the effectiveness of HPV vaccination as a strategy for cervical cancer control can be measured either by monitoring secular trends in cervical cancer incidence or by conducting randomized trials. The former approach is unlikely to provide convincing evidence of effectiveness, since cervical cancer rates are subject to strong secular trends that are independent of intervention measures. A few phase III trials of HPV prophylactic vaccines are being started. Such trials are very expensive studies involving frequent and complicated investigations. It is important, however, to start as soon as possible simpler trials which may demonstrate the effectiveness of HPV vaccine in field conditions, i.e. in developing countries which do not have the resources to mount effective cytology-based screening programs, yet suffer the major burden of mortality from cervical cancer. Such trials may capture a difference in the most severe, and rarest, preinvasive cervical lesions. The design of such studies is briefly considered for two areas: Southern India and South Korea. Finally, projections of the number of cases of cervical cancer following the introduction of mass vaccination are given for developed and developing countries.

Prevalence and determinants of HPV infection among Colombian women with normal cytology

Human papillomavirus is the principal risk factor associated with cervical cancer, the most common malignancy among women in Colombia. We conducted a survey, aiming to report type specific prevalence and determinants of human papillomavirus infection in women with normal cytology. A total of 1859 women from Bogota, Colombia were interviewed and tested for human papillomavirus using a general primer GP5+/GP6+ mediated PCR-EIA. The overall HPV DNA prevalence was 14.8%; 9% of the women were infected by high risk types, 3.1% by low risk types, 2.3% by both high risk/low risk types and 0.4% by uncharacterized types (human papillomavirus X). Thirty-two different human papillomavirus types were detected, being human papillomavirus 16, 58, 56, 81(CP8304) and 18 the most common types. The human papillomavirus prevalence was 26.1% among women younger than 20 years, 2.3% in women aged 45-54 years, and 13.2% in women aged 55 years or more. For low risk types the highest peak of prevalence was observed in women aged 55 years or more. Compared to women aged 35-44 years, women aged less than 20 years had a 10-fold increased risk of having multiple infections. Besides age, there was a positive association between the risk of human papillomavirus infection and number of regular sexual partners and oral contraceptive use. In women aged below 25 years, high educational level and having had casual sexual partners predicted infection risk. In conclusion, there was a broad diversity of human papillomavirus infections with high risk types being the most common types detected. In this population multiplicity of sexual partners and, among young women, high educational level and casual sexual partners seem to determine risk.

Imiquimod 5% cream in the treatment of anogenital warts in female patients

OBJECTIVE

To investigate the efficacy and safety of imiquimod 5% cream in the treatment of anogenital warts in a female population.

METHODS

In two open-label studies, female patients with anogenital warts applied imiquimod 5% cream three times a week for up to 16 weeks. Patients who cleared their warts were monitored for a 6-month follow-up period. Patients could be re-treated with imiquimod 5% cream for up to an additional 16 weeks if their warts recurred or new warts developed during the follow-up period. The treatment period could also be extended for up to an additional 16 weeks if patients only experienced partial clearance during the initial 16-week treatment period.

RESULTS

Of the female patients who applied imiquimod 5% cream, 75% (449/600) experienced complete clearance of their warts (treatment failure analysis). This includes 46 patients who experienced total clearance when they applied imiquimod for longer than 16 weeks as their warts had only partially cleared in the initial 16 weeks of therapy. During the 6 months of follow-up after the initial treatment period, 15% of patients had recurrent warts. Thirty-nine (75%) of those patients experienced total clearance again after they re-applied imiquimod for up to an additional 16 weeks. The most frequently observed local skin reaction was erythema.

CONCLUSION

In these studies, imiquimod 5% cream was an effective and well-tolerated treatment for anogenital warts in females and continued to be safe and effective in the small proportion of patients who needed to re-apply imiquimod after wart recurrence.

The causal relation between human papillomavirus and cervical cancer

The causal role of human papillomavirus infections in cervical cancer has been documented beyond reasonable doubt. The association is present in virtually all cervical cancer cases worldwide. It is the right time for medical societies and public health regulators to consider this evidence and to define its preventive and clinical implications. A comprehensive review of key studies and results is presented.

Human papillomavirus in cervical cancer

Epidemiologic studies supported by molecular technology have provided sufficient evidence of the causal role of some human papillomavirus (HPV) infections in the development of cervical cancer. The finding is consistent universally, and HPV has been proposed as the first identified necessary cause of cervical cancer. Such recognition translates into the concept that cervical cancer does not develop without persistent presence of HPV DNA. In the developed parts of the world, cytologic screening programs could benefit from the addition of HPV testing to their protocols. Controlled studies and one randomized trial have shown that HPV testing is helpful in solving the ambiguous cases generated by cytology reading. In populations where cytology programs are not functional or efficient, HPV testing is being evaluated as an alternative means of primary screening. Prevention of exposure to high-risk HPV types, either by prophylactic vaccination or by combined prophylactic and therapeutic immunologic intervention, may prove to be the most efficient and logistically feasible option for the prevention of cervical cancer in developing populations.

Molecular detection and genotyping of human papillomavirus

Human papillomavirus infections are associated with the development of cervical neoplasia. Human papillomavirus is a group of heterogeneous viruses, comprising many genotypes, which can be divided into high-risk and low-risk types, depending on their association with disease. Therefore, accurate molecular diagnostic tools are required for detection and identification of human papillomavirus. Monitoring of human papillomavirus infection is necessary for adequate patient management and follow-up during treatment. This review describes the different molecular methods available for human papillomavirus detection and identification of genotypes.

Asian-American variants of human papillomavirus 16 and risk for cervical cancer: a case-control study

BACKGROUND

Human papillomavirus 16 (HPV16) has a number of variants, each with a different geographic distribution and some that are associated more often with invasive neoplasias. We investigated whether the high incidence of cervical cancer in Mexico (50 cases per 100 000 women) may be associated with a high prevalence of oncogenic HPV16 variants.

METHODS

Cervical samples were collected from 181 case patients with cervical cancer and from 181 age-matched control subjects, all from Mexico City. HPV16 was detected with an E6/E7 gene-specific polymerase chain reaction, and variant HPV classes and subclasses were identified by sequencing regions of the E6 and L1/MY genes. Clinical data and data on tumor characteristics were also collected. All statistical tests were two-sided.

RESULTS

HPV16 was detected in cervical scrapes from 50.8% (92 of 181) of case patients and from 11% (20 of 181) of control subjects. All HPV16-positive samples, except one, contained European (E) or Asian-American (AA) variants. AA and E variants were found statistically significantly more often in case patients (AA = 23.2% [42 of 181]; E = 27.1% [49 of 181]) than in control subjects (AA = 1.1% [two of 181]; E = 10% [18 of 181]) (P<.001 for case versus control subjects for either E or AA variants, chi2 test). However, the frequency of AA variants was 21 times higher in cancer patients than in control subjects, whereas that ratio for E variants was only 2.7 (P =.006, chi2 test). The odds ratio (OR) for cervical cancer associated with AA variants (OR = 27.0; 95% confidence interval [CI] = 6.4 to 113.7) was higher than that associated with E variants (OR = 3.4; 95% CI = 1.9 to 6.0). AA-positive case patients (46.2 +/- 12.5 years [mean +/- standard deviation]) were 7.7 years younger than E-positive case patients (53.9 +/- 12.2 years) (P =.004, Student's t test). AA variants were associated with squamous cell carcinomas and adenocarcinomas, but E variants were associated with only squamous cell carcinomas (P =.014, Fisher's exact test).

CONCLUSIONS

The high frequency of HPV16 AA variants, which appear to be more oncogenic than E variants, might contribute to the high incidence of cervical cancer in Mexico.