HPV co-factors related to the development of cervical cancer: results from a population-based study in Costa Rica

Human papillomavirus genotypes and cofactors causing cervical intraepithelial neoplasia and cervical cancer in Korean women

OBJECTIVE

Infection with human papillomavirus (HPV) is a necessary cause of cervical cancer, but the risk associated with the various viral types and related cofactors have not been adequately assessed in Korean women. This study aimed to investigate the genotype distribution of HPV and cofactors related to cervical carcinogenesis in Korean women.

MATERIALS AND METHODS

We conducted a hospital-based case-control study in 215 women with histologically confirmed cervical neoplasia (111 cases of cervical intraepithelial neoplasia [CIN] and 104 cases of invasive cervical cancer [ICC]) and 1214 healthy control women. Polymerase chain reaction-based dot blot assays were used for detection of 16 high-risk HPV types. To clarify the cofactors, we administered questionnaires evaluating smoking, drinking, and sexual and reproductive history from women infected with HPV.

RESULTS

Human papillomavirus was detected in 86.5% of the women with CIN and 96.2% of the women with ICC compared to 14.6% of the control women. The most common HPV types were, in descending order of frequency, types 16, 58, 18, 33, and 66 for CIN, and types 16, 18, 31, and 33 for ICC. Among the control women, HPV 16, 66, 33, 58, 18, and 31 were the most common types. Smoking and higher number of births (≥3) were associated with CIN (odds ratio [OR], 2.49; 95% confidence interval [CI], 1.21-5.15, and OR, 2.67; 95% CI, 1.36-5.28, respectively). This relationship was also found in the women with ICC (OR, 3.42; 95% CI, 1.59-7.38, and OR, 2.17; 95% CI, 1.08-4.38, respectively) compared to controls. In addition, the circumcision of sexual partner and the sexual habit of condom use were protective factors for ICC (OR, 0.47; 95% CI, 0.24-0.90, and OR, 0.19; 95% CI, 0.06-0.57, respectively).

CONCLUSION

Human papillomavirus types 16, 18, 31, 33, and 58 are the major causative genotypes for cervical carcinogenesis in Korean women. Smoking and multiparity seem to be the most significant cofactors.

Association between smoking and size of anal warts in HIV-infected women

While the association between smoking and human papillomavirus infection, cervical cancer, and anal cancer has been well studied, evidence on the association between cigarette smoking and anal warts is limited. The purpose of this study was to investigate if cigarette smoking status influences the size of anal warts over time in HIV-infected women in a sample of 976 HIV-infected women from the Women's Interagency HIV Study (WIHS). A linear mixed model was used to determine the effect of smoking on anal wart size. Even though women who were currently smokers had larger anal warts at baseline and slower growth rate of anal wart size after each visit than women who were not current smokers, there was no association between size of anal wart and current smoking status over time. Further studies on the role of smoking and interaction between smoking and other risk factors, however, should be explored.

Risk for cervical intraepithelial neoplasia grade 3 or worse in relation to smoking among women with persistent human papillomavirus infection

BACKGROUND

Smoking has been associated with cervical cancer. We examined whether smoking increases the risk for high-grade cervical lesions in women with high-risk human papillomavirus (HPV) infection.

METHODS

In a population-based cohort study, 8,656 women underwent a structured interview, and subsequently cervical cells were obtained for HPV DNA testing. Women with high-risk HPV infection and no prevalent cervical disease at baseline (n = 1,353) were followed through the Pathology Data Bank for cervical lesions for up to 13 years. Separate analyses of women with persistent high-risk HPV infection (n = 312) were also conducted. HRs for a diagnosis of cervical intraepithelial neoplasia grade 3 or worse/high-grade squamous intraepithelial lesions or worse (CIN3+) and the corresponding 95% confidence intervals (CI) were calculated in the two groups.

RESULTS

Among high-risk HPV-positive women, an increased risk for CIN3+ was associated with long-term smoking (≥10 years) and heavy smoking (≥20 cigarettes/d). In the subgroup of women with persistent HPV infection, heavy smoking was also associated with a statistically significantly higher risk for CIN3+ than never smoking (HR, 1.85; 95% CI, 1.05-3.22, adjusted for length of schooling, parity, and HPV type at baseline). The average number of cervical cytology screening tests per year during follow-up did not explain the differences in risk in relation to smoking (P = 0.4).

CONCLUSIONS

Smoking is associated with an increased risk for subsequent high-grade cervical lesions in women with persistent high-risk HPV infection.

IMPACT

Our study adds to the understanding of the role of smoking in the natural history of HPV and cervical carcinogenesis.

Baseline human papillomavirus infection, high vaginal parity, and their interaction on cervical cancer risks after a follow-up of more than 10 years

OBJECTIVES

Human papillomavirus (HPV) has been recognized as a major factor for cervical cancer causation. Other factors, relating to reproduction, are also important. This study aims to disentangle the roles of baseline HPV infection, high vaginal parity (defined as having ≥4 vaginal deliveries), and the interaction between the two in predicting cervical cancer risk.

METHODS

The authors apply a newly developed causal-pie modeling technique to analyze a cohort of more than 10,000 women conducted in Taiwan with more than 10 years of follow-up. The rate ratios adjusted by age and menopausal status were further modeled by an additive Poisson regression with non-negative parameters. The index of causal-pie weight (CPW) was calculated to indicate the proportion of cervical cancer cases attributable to a particular class of causal pies.

RESULTS

It was found that the CPWs are 36.3 % for baseline HPV infection, 35.6 % for baseline HPV infection and high vaginal parity, and 28.1 % for other factors.

CONCLUSIONS

A causal-pie modeling based on a women cohort in Taiwan successfully disentangles the roles of virus factors and reproductive factors at study entry, independently or interactively, on subsequent cervical cancer risk.

Age-group differences in human papillomavirus types and cofactors for cervical intraepithelial neoplasia 3 among women referred to colposcopy

BACKGROUND

Recommendations for high-risk human papillomavirus (HR-HPV) testing as an adjunct to cytology for cervical cancer screening differ by age group, because HR-HPV tests lack adequate specificity in women aged <30. Here, we assess age-group differences in HPV types and other risk factors for cervical intraepithelial neoplasia (CIN) grade 3 or worse (CIN3+) versus CIN0-2 in women from four colposcopy clinics.

METHODS

Women ages 18 to 69 (n = 1,658) were enrolled and completed structured interviews to elicit data on behavioral risk factors prior to their examinations. HPV genotyping was done on exfoliated cervical cell samples. We estimated relative risks (RR) for HPV types and cofactors for CIN3+, overall and stratified by age group.

RESULTS

After 2 years of follow-up, we identified 178 CIN3+, 1,305 CIN0-2, and 175 indeterminate outcomes. Nonvaccine HR-HPV types were only associated with CIN3+ among women ≥ 30 (RR = 2.3, 95% CI: 1.5-3.4; <30: RR = 0.9). Among all HR-HPV-positive women, adjusting for age, significant cofactors for CIN3+ included current smoking (RR = 1.5), former smoking (RR = 1.8), regular Pap screening (RR = 0.7), current regular condom use (RR = 0.5), and parity ≥ 5 (RR = 1.6, P(trend) for increasing parity = 0.07). However, the parity association differed by age group (≥ 30: RR = 1.8, P(trend) = 0.008; <30: RR = 0.9; P(trend) =.55).

CONCLUSION

Subgroup variation by age in the risk of CIN3+ points to the importance of the timing of exposures in relation to CIN3+ detection.

IMPACT

Future screening strategies need to consider natural history and secular trends in cofactor prevalence in the pursuit of appropriately sensitive and specific screening tools applied to appropriate age groups.

Analysis of 4 single-nucleotide polymorphisms in relation to cervical dysplasia and cancer development using a high-throughput ligation-detection reaction procedure

BACKGROUND

Host genetic characteristics and environmental factors may correlate with risk for cervical cancer development. Here we describe a retrospective screening study for single nucleotide polymorphisms (SNPs) in genetic markers TP53, MTHFR, CYP1A1, and CYP2E1 in 749 patients.

METHODS

A multiplex ligation-dependent polymerase chain reaction approach was applied. We used archived material from human papillomavirus tests and correlated SNP genotypes to the corresponding clinical data. Semantic integration was used to identify and evaluate the clinical status from electronic health records.

RESULTS

An association with cervical cancer and high-grade dysplasia was found for the rare homozygous CC genotype (rs4646903) in CYP1A1 (odds ratio [OR], 8.862). Odds ratios were also significantly elevated for heterozygous MTHFR CT genotype (rs1801133; OR, 1.457). No significant association was found in TP53 (rs1042522) and CYP2E1 (rs3813867). In addition, we found smokers at higher risk (OR, 2.688) and identified pregnancies as a significant risk factor (OR, 1.54).

CONCLUSIONS

Our protocol enables a feasible way for further retrospective large sample size evaluation of potential genetic markers. This study revealed genetic associations of a rare SNP genotype with cervical dysplasia in one of the largest patient sample to date that warrants further investigation.

High-risk human papillomavirus associated with incident cervical intraepithelial neoplasia developing in mothers in the Finnish Family HPV Study cohort

BACKGROUND

Cofactors of high-risk (HR) human papillomavirus (HPV) in the progression of cervical intraepithelial neoplasia (CIN) are incompletely characterized. In this study these cofactors were investigated in a longitudinal setting.

METHODS

A cohort of 329 women (mean age 25.5 y) were enrolled in the Finnish Family HPV Study, and followed-up for 6 y with serial cervical samples for HPV genotyping, virus integration status, and HPV serology. Hospital records were reviewed until March 2010 and linked with HPV detection data. All incident CIN lesions were subjected to HPV genotyping. HPV covariates were studied in an age- and HPV-matched nested case-control (1:4) setting.

RESULTS

Twelve of the 329 women developed an incident CIN: 2 CIN1, 3 CIN2, and 7 CIN3. HPV16 was detected most frequently (7/12), followed by HPV58 (2/12), HPV18, HPV31, and HPV42. HPV integration was present in 4/12 cases. Long-lasting persistence of HPV31 and HPV16 preceded incident CIN2 and CIN3. In multivariate conditional logistic regression, the risk for incident CIN increased up to 4-fold with increasing number of deliveries (p = 0.024) and decreased with history of genital warts (p = 0.036).

CONCLUSION

Baseline HR-HPV infections and their persistence precede incident CIN by several years. The 2 independent covariates of HR-HPV were (1) number of deliveries (increasing the risk), and (2) history of genital warts (protective effect).

Co-factors of high-risk human papillomavirus infections display unique profiles in incident CIN1, CIN2 and CIN3

In addition to oncogenic 'high-risk' human papillomaviruses (HR-HPV), several co-factors are needed in cervical carcinogenesis, but it is poorly understood whether these HPV co-factors associated with incident cervical intraepithelial neoplasia (CIN) grade 1 are different from those required for progression to CIN2 and CIN3. To gain further insights into the true biological differences between CIN1, CIN2 and CIN3, we assessed HPV co-factors increasing the risk of incident CIN1, CIN2 and CIN3. Data from the New Independent States of the Former Soviet Union (NIS) Cohort (n = 3187) and the Latin American Screening (LAMS) Study (n = 12,114) were combined, and co-factors associated with progression to CIN1, CIN2 and CIN3 were analysed using multinomial logistic regression models with all covariates recorded at baseline. HR-HPV-positive women (n = 1105) represented a subcohort of all 1865 women prospectively followed up in both studies. Altogether, 90 (4.8%), 39 (2.1%) and 14 (1.4%) cases progressed to CIN1, CIN2 and CIN3, respectively. Baseline HR-HPV was the single most powerful predictor of incident CIN1, CIN2 and CIN3. When controlled for residual HPV confounding by analysing HR-HPV-positive women only, the risk profiles of incident CIN1, CIN2 and CIN3 were unique. Completely different HPV co-factors were associated with progression to CIN1, CIN2 and CIN3 in univariate and multivariate analyses, irrespective of whether non-progression, CIN1 or CIN2 was used as the reference outcome. HPV co-factors associated with progression to CIN1, CIN2 and CIN3 display unique profiles, implicating genuine biological differences between the three CIN grades, which prompts us to re-visit the concept of combining CIN2 with CIN3 or CIN1.

Predictors of human papilloma virus (HPV) infection in Italian women

HPV infection is a "necessary cause" of cervical cancer and it is sexually transmitted. Due to upcoming mass vaccination investigation on risk factors for infection is the basis to implement prophylactic strategy even in older women. The aim of the study was to evaluate predictors of high-risk (HR) HPV infection in adult women. Between 2006 and 2008, 100 women aged >18 years, with no previous treatment for cervical lesions, were screened for HR HPV infection in Rome, Italy. Risk factors for HPV infection were investigated through a questionnaire including: ethnicity, religion, education, marital status, sexual behavior, gynecological and obstetrical history, smoking and alcohol intake. Multivariate analysis identified the "never married-separated/divorced" status (OR: 3.38; 95% CI: 1.14-10.12) as predictor of HPV infection, while having a higher age at the first sexual intercourse (FSI) shows a protective effect (OR: 0.84; 95% CI: 0.71-1.00). A trend for the association between the infection and having more than three lifetime partners was also observed (OR: 2.57; 95% CI: 0.86-7.71). No significant association was found for other demographic characteristics investigated. These findings provide a contribution in the knowledge of an adult population defining a "high-risk" sexual behavioral profile and could be helpful to target prophylactic strategies in older woman.

Outcome of expectant management of cervical intraepithelial neoplasia grade 2 in women followed for 12 months

OBJECTIVE

To evaluate the outcome of CIN 2 diagnosed by colposcopy-directed biopsy in women followed without treatment for 12 months and to verify whether the regression and progression of this lesion are associated with the woman's age at diagnosis and age at first sexual intercourse.

STUDY DESIGN

Women diagnosed with CIN 2 by biopsy and with previous cervical smear showing LSIL were included in this cohort study and followed up for one year with cervical smear and colposcopy every three months. The rates of progression, persistence and regression of the CIN 2 were evaluated. The Kruskal-Wallis test was used to analyze the woman's age at diagnosis, age at first sexual intercourse and interval since the first sexual intercourse according to the CIN 2 outcome, assuming a significance level of 5%.

RESULTS

At the end of 12 months of follow-up the CIN 2 regression rate was 74% (31/42), progression rate to CIN 3 was 24% (10/42) and in one case CIN 2 persisted (2%). Among women who had regression, this event was detected in the first six months of follow-up in 26 of the 31 cases. There was no statistically significant association between the evolution of CIN 2 and the woman's age at diagnosis, age at first sexual intercourse and interval since first sexual intercourse. Women whose lesions were restricted to one quadrant were more likely to have CIN 2 regression at three-month follow-up compared with women with a lesion extending to one or more quadrants (OR: 6.50; 95% CI: 1.20-35.23).

CONCLUSIONS

The results of this study indicate that the majority of CIN 2 diagnosed by biopsy in women with previous Pap smear showing LSIL will regress in 12 months and therefore an expectant approach could be considered in these cases, not only for young women. Nevertheless these findings are not conclusive, and larger studies are required in order to certify when it is safe to adopt expectant management for CIN 2.

Lifestyle behaviors in Massachusetts adult cancer survivors

INTRODUCTION

Adoption of healthy lifestyles in cancer survivors has potential to reduce subsequent adverse health. We sought to determine the prevalence of tobacco use, alcohol use, and physical inactivity among cancer survivors overall and site-specific survivors.

METHODS

We performed a cross-sectional analysis of the Massachusetts Behavioral Risk Factor Surveillance System, 2006-2008, and identified 1,670 survivors and 18,197 controls. Specific cancer sites included prostate, colorectal, female breast, and gynecologic (cervical, ovarian, uterine). Covariates included age, gender, race/ethnicity, education, income, marital status, health insurance, and physical and mental health. Gender stratified logistic regression models associated survivorship with each health behavior.

RESULTS

4.9% of men and 7.7% of women reported a cancer history. In adjusted regression models, male survivors were similar to gender matched controls, while female survivors had comparable tobacco and alcohol use but had more physical inactivity than controls (OR 1.5; 95% CI, 1.2-1.8). By site, breast cancer survivors were more likely to be physically inactive (OR 1.5; 95% CI, 1.1-2.0) and gynecologic cancer survivors were more likely to report current tobacco use (OR 1.8; 95% CI, 1.2-2.8).

CONCLUSIONS AND IMPLICATIONS FOR CANCER SURVIVORS

Specific subgroups of cancer survivors are more likely to engage in unhealthy behaviors. Accurate assessment of who may derive the most benefit will aid public health programs to effectively target limited resources.

Human papillomavirus genotypes in cervical intraepithelial neoplasia grade 3

BACKGROUND

There are few large case series describing the human papillomavirus (HPV) genotypes found in women diagnosed with rigorously reviewed cervical intraepithelial neoplasia grade 3 (CIN3), cervical precancer.

METHODS

The Atypical Squamous Cells of Undetermined Significance (ASCUS) and Low-Grade Squamous Intraepithelial Lesion (LSIL) Triage Study (ALTS) was a clinical trial to evaluate the best management strategies for women with equivocal (ASCUS) or mildly abnormal (LSIL) Pap tests. During enrollment and the 2-year follow-up, 608 women had a histopathologic diagnosis of CIN3 and PCR-based HPV genotyping results on cervical specimens. The genotyping results were ranked hierarchically according to cancer risk: HPV16 > other carcinogenic HPV > noncarcinogenic HPV > PCR negative.

RESULTS

Among the 608 women diagnosed with CIN3, 601 (98.8%) cases were positive for any HPV genotype and 95.4% for any carcinogenic HPV. HPV16 (59.9%), HPV31 (18.1%), HPV52 (14.8%), HPV51 (14.0%), and HPV18 (13.2%) were the five most common HPV genotypes detected. Younger age, consensus histologic confirmation, smoking, and multiparity increased the likelihood of testing HPV 16 positive. Specifically, HPV16-positive CIN3 occurred at a younger age than CIN3 positive for other carcinogenic HPV genotypes (median of 23.5 years versus 25 years, respectively; P = 0.0003, Kruskal-Wallis).

CONCLUSIONS

HPV16-positive CIN3 was more commonly diagnosed in younger women (versus older women), with consensus diagnosis (versus some disagreement between reviewers), and in smokers (versus nonsmokers), and was less commonly diagnosed in multiparous women compared CIN3 positive for other carcinogenic HPV genotypes.

IMPACT

In populations vaccinated against HPV16 (and HPV18), the median age of CIN3 in women with ASCUS and LSIL cytology should shift to older ages, possibly permitting later age at first screening.

Coverage of Jade Goody's cervical cancer in UK newspapers: a missed opportunity for health promotion?

BACKGROUND

It has been claimed that publicity surrounding popular celebrity Jade Goody's experience of cervical cancer will raise awareness about the disease. This study examines the content of newspaper articles covering her illness to consider whether 'mobilising information' which could encourage women to adopt risk-reducing and health promoting behaviours has been included.

METHODS

Content analysis of 15 national newspapers published between August 2008 and April 2009

FINDINGS

In the extensive coverage of Goody's illness (527 articles in the 7 months of study) few newspaper articles included information that might make women more aware of the signs and symptoms or risk factors for the disease, or discussed the role of the human papilloma virus (HPV) and the recently introduced HPV vaccination programme to reduce the future incidence of cervical cancer. For example, less than 5% of articles mentioned well-known risk-factors for cervical cancer and less than 8% gave any information about HPV. The 'human interest' aspects of Goody's illness (her treatment, the spread of her disease in later months, her wedding, and her preparations for her children's future) were more extensively covered.

CONCLUSIONS

Newspaper coverage of Goody's illness has tended not to include factual or educational information that could mobilise or inform women, or help them to recognise early symptoms. However, the focus on personal tragedy may encourage women to be receptive to HPV vaccination or screening if her story acts as a reminder that cervical cancer can be a devastating and fatal disease in the longer term.

Molecular Variants of HPV Type 16 E6 Among Honduran Women

OBJECTIVE

In this study, we investigated the prevalence of human papillomavirus 16 (HPV-16) variants in Honduran women with normal cytology and with dysplasia and cervical cancer.

METHODS

Samples identified as positive for HPV-16 by SPF10-LiPA were tested for intratypic subtypes and variants by analysis of the E6/E7 region using a novel reverse hybridization assay (line probe assay).

RESULTS

We found that most infections in all clinical groups belong to the E6 European variants, suggesting that HPV-16 non-European variants do not represent an additional factor associated with increased occurrence of high-grade cervical lesions in the studied population. Among the 106 HPV-16-positive women analyzed, E-350G was the most prevalent variant in all different disease stages, being present in 18% of cervical cancer, 13% of cervical intraepithelial neoplasia grade III (CIN III), 5% of CIN II, 5% of CIN I, and 20% of control samples. Mixed variants of HPV-16 infections were detected in 7.7% of the samples, mostly in women with normal cytology.

CONCLUSIONS

This study shows for the first time the diversity of HPV-16 variants in cervical samples of Honduran women.

Smoking behavior in women with locally advanced cervical carcinoma: a Gynecologic Oncology Group study

OBJECTIVE

The purpose of this study was to assess cigarette use and environmental smoke exposure in women with cervical cancer.

STUDY DESIGN

Smoking behavior was recorded prospectively in a clinical trial of women with locally advanced cervical carcinoma.

RESULTS

Of 315 participants, 133 women (42%) were current smokers; 72 women (23%) were former smokers, and 110 women (35%) were never smokers. Current smokers began smoking earlier (16 vs 18 years; P = .009), for more years (29 vs 24 years; P = .005), and in greater amounts (20 vs 11 cigarettes/d; P < .001) than former smokers. Active smokers lived more often with another smoker (63.3%), compared with former smokers (35.0%; P < .001) or never-smokers (28.7%; P < .001). Agreement between self-report and urine cotinine level was high (kappa = 0.872; P < .001). A significant decrease in cotinine level during treatment occurred in 5.2% of current smokers.

CONCLUSION

Prevalence of smoking and tobacco consumption was twice that of the North American female population. Few smokers quit or decreased consumption during treatment.

Inducible heat shock protein 70 enhances HPV31 viral genome replication and virion production during the differentiation-dependent life cycle in human keratinocytes

Increasing data indicate heat shock proteins (HSPs) including inducible HSP70 (HSP70i) are involved in the replicative cycles of various viruses including adenoviruses (Ads), polyomaviruses (PyVs), and some RNA viruses. Cell-free system studies implicate HSP70i in human papillomavirus type 11 (HPV11) genome replication with E1 and E2 proteins, and there is evidence that HSP70 is involved in capsid assembly and disassembly for PyVs and HPVs. HSP70 expression is increased in HPV16 E6/E7 gene transduced human primary keratinocytes, and frequently detected in early stage uterine cervical cancer at levels in conjunction with lesion severity. In this study we carry out analyses in the natural host epithelial tissues to assess the role of inducible HSP70 (HSP70i) in the HPV infectious life cycle. For these studies we used the organotypic (raft) culture system to recapitulate the full viral life cycle of the high-risk HPV31. Upon heat shock of HPV31-infected organotypic tissues, we find high and sustained expression of HSP70i coincident with enhanced HPV genome replication and virion production. Whereas there is no clear effect on L1 expression levels, we find HSP70i and L1 interact and HSP70i colocalizes with and enhances the nuclear localization of L1 in differentiated cells. Ad-mediated gene transfer was used to study the effects of HSP70i in naturally HPV-infected differentiating tissues and showed results similar to those in heat shocked rafts. These results indicate that increased HSP70i augments late activities in the viral life cycle. We conclude that HSP70i contributes directly to HPV replicative viral activities and the production of infectious virions.

[Human papillomavirus and cervical neoplasia]

Human papillomavirus (HPV) has been established as an important etiological factor for the development of cervical cancer. This DNA virus primarily infects the epithelium and can induce benign and malignant lesions of the mucous membranes and skin. Some HPVs are considered high risk due to their role in malignant progression of cervical tumors. Genital HPV infections are common and usually transient among young sexually active women. Only a small fraction of infected women develop cervical cancer, implying the involvement of environmental and genetic cofactors in cervical carcinogenesis. Classification, virology, pathology, natural history, epidemiological features of genital HPV infection, and future prospects for cervical cancer prevention with HPV vaccines will be reviewed here.

The role of retinoid deficiency and estrogens as cofactors in cervical cancer

Persistent infection with high-risk human papillomaviruses (HR-HPVs) is involved in cervical cancer (CC), a major cause of cancer mortality worldwide. Infection occurs primarily at the transformation zone (TZ), the most estrogen- and retinoid-sensitive region of the cervix. Development of CC affects a small percentage of HR-HPV-infected women and often takes decades after infection, suggesting that HR-HPV is a necessary but not sufficient cause of CC. Thus, other cofactors are necessary for progression from cervical HR-HPV infection to cancer such as long-term use of hormonal contraceptives, multiparity, smoking, as well as micronutrient depletion and in particular retinoid deficiency, which alters epithelial differentiation, cellular growth and apoptosis of malignant cells. Therefore, early detection of HR-HPV and management of precancerous lesions together with a profound understanding of additional risk factors could be a strategy to avoid this disease. In this review we focus on the synergic effect of estrogens, retinoid deficiency and HR-HPVs in the development of CC. These risk factors may act in concert to induce neoplastic transformation in squamous epithelium of the cervix, setting the stage for secondary genetic or epigenetic events leading to cervical cancer.

Cervical cancer: the sub-Saharan African perspective

Cervical cancer is the second most common cancer in women worldwide and the leading cause of cancer deaths in developing countries. While incidence and mortality rates of cervical cancer have fallen significantly in developed countries, 83% of all new cases that occur annually and 85% of all deaths from the disease occur in developing countries. Cervical cancer is the most common cancer among women in sub-Saharan Africa. The incidence is on the increase in some countries. Knowledge and awareness of this disease on the continent are very poor and mortality still very high. Facilities for the prevention and treatment of cervical cancer are still very inadequate in many countries in the region. Governments in sub-Saharan Africa must recognise cervical cancer as a major public health concern and allocate appropriate resources for its prevention and treatment, and for research. Indeed, cervical cancer in this region must be accorded the same priority as HIV, malaria, tuberculosis and childhood immunisations.

The EVER proteins as a natural barrier against papillomaviruses: a new insight into the pathogenesis of human papillomavirus infections

Infections by human papillomaviruses (HPVs) are the most frequently occurring sexually transmitted diseases. The crucial role of genital oncogenic HPV in cervical carcinoma development is now well established. In contrast, the role of cutaneous HPV in skin cancer development remains a matter of debate. Cutaneous beta-HPV strains show an amazing ubiquity. The fact that a few oncogenic genotypes cause cancers in patients suffering from epidermodysplasia verruciformis is in sharp contrast to the unapparent course of infection in the general population. Our recent investigations revealed that a natural barrier exists in humans, which protects them against infection with these papillomaviruses. A central role in the function of this HPV-specific barrier is played by a complex of the zinc-transporting proteins EVER1, EVER2, and ZnT-1, which maintain cellular zinc homeostasis. Apparently, the deregulation of the cellular zinc balance emerges as an important step in the life cycles not only of cutaneous but also of genital HPVs, although the latter viruses have developed a mechanism by which they can break the barrier and impose a zinc imbalance. Herein, we present a previously unpublished list of the cellular partners of EVER proteins, which points to future directions concerning investigations of the mechanisms of action of the EVER/ZnT-1 complex. We also present a general overview of the pathogenesis of HPV infections, taking into account the latest discoveries regarding the role of cellular zinc homeostasis in the HPV life cycle. We propose a potential model for the mechanism of function of the anti-HPV barrier.

Depot-medroxyprogesterone acetate and combined oral contraceptive use and cervical neoplasia among women with oncogenic human papillomavirus infection

OBJECTIVE

The objective of the study was to examine the relationship of depot-medroxyprogesterone acetate (DMPA) and combined oral contraceptive (COC) use with cervical intraepithelial neoplasia (CIN).

STUDY DESIGN

Two case-control studies of women who presented for gynecologic care and underwent cytologic and human papillomavirus (HPV) testing were performed. The first included oncogenic HPV-positive women grouped based on histology: negative (n = 152), CIN1 (n = 133), and CIN2-3 or greater (n = 173). For the second, 2 groups were identified: negative HPV/negative histology (n = 107) and positive oncogenic HPV/negative histology (n = 152).

RESULTS

Among oncogenic HPV-positive women, DMPA use was inversely associated with CIN2-3 or greater (adjusted odds ratio [OR(adj)], 0.4; 95% confidence interval [CI], 0.2-1.1) and CIN1 (OR(adj), 0.1; 95% CI, 0.01-0.6); COC use was not associated with either. Among histologically negative women, DMPA use was associated with oncogenic HPV (OR(adj), 4.7; 95% CI, 1.4-15.8).

CONCLUSION

Among women with oncogenic HPV, hormonal contraceptive use was not associated with an increased risk of CIN2-3 or greater. Longer-term DMPA use may attenuate the colposcopic and histologic features of CIN because women reporting such use were more likely than others to have cervical oncogenic HPV without evidence of CIN.

Cervical carcinoma and sexual behavior: collaborative reanalysis of individual data on 15,461 women with cervical carcinoma and 29,164 women without cervical carcinoma from 21 epidemiological studies

High-risk human papillomavirus (HPV) types cause most cervical carcinomas and are sexually transmitted. Sexual behavior therefore affects HPV exposure and its cancer sequelae. The International Collaboration of Epidemiological Studies of Cervical Cancer has combined data on lifetime number of sexual partners and age at first sexual intercourse from 21 studies, or groups of studies, including 10,773 women with invasive cervical carcinoma, 4,688 women with cervical intraepithelial neoplasia grade 3 (CIN3)/carcinoma in situ, and 29,164 women without cervical carcinoma. Relative risks for invasive cancer and CIN3 were estimated by conditional logistic regression. Risk of invasive cervical carcinoma increased with lifetime number of sexual partners (P for linear trend <0.001). The relative risk for > or =6 versus 1 partner, conditioned on age, study, and age at first intercourse, was 2.27 [95% confidence interval (95% CI), 1.98-2.61] and increased to 2.78 (95% CI, 2.22-3.47) after additional conditioning on reproductive factors. The risk of invasive cervical carcinoma increased with earlier age at first intercourse (P for linear trend <0.001). The relative risk for age at first intercourse < or =14 versus > or =25 years, conditioned on age, study, and lifetime number of sexual partners was 3.52 (95% CI, 3.04-4.08), which decreased to 2.05 (95% CI, 1.54-2.73) after additional conditioning on reproductive factors. CIN3/carcinoma in situ showed a similar association with lifetime number of sexual partners; however, the association with age at first intercourse was weaker than for invasive carcinoma. Results should be interpreted with caution given the strong correlation between sexual and reproductive factors and the limited information on HPV status.

Smoking enhances risk for new external genital warts in men

Repeat episodes of HPV-related external genital warts reflect recurring or new infections. No study before has been sufficiently powered to delineate how tobacco use, prior history of EGWs and HIV infection affect the risk for new EGWs. Behavioral, laboratory and examination data for 2,835 Multicenter AIDS Cohort Study participants examined at 21,519 semi-annual visits were evaluated. Fourteen percent (391/2835) of men reported or were diagnosed with EGWs at 3% (675/21,519) of study visits. Multivariate analyses showed smoking, prior episodes of EGWs, HIV infection and CD4+ T-lymphocyte count among the infected, each differentially influenced the risk for new EGWs.

Is smoking an independent risk factor for invasive cervical cancer? A nested case-control study within Nordic biobanks

The strong correlation between smoking and exposure to oncogenic human papillomaviruses (HPVs) has made it difficult to verify the independent role of smoking in cervical carcinogenesis. Thus, the authors evaluated this role. Five large Nordic serum banks containing samples from more than 1,000,000 subjects were linked with nationwide cancer registries (1973-2003). Serum samples were retrieved from 588 women who developed invasive cervical cancer and 2,861 matched controls. The samples were analyzed for cotinine (a biomarker of tobacco exposure) and antibodies to HPV types 16 and 18, herpes simplex virus type 2, and Chlamydia trachomatis. Smoking was associated with the risk of squamous cell carcinoma (SCC) among HPV16- and/or HPV18-seropositive heavy smokers (odds ratio=2.7, 95% confidence interval: 1.7, 4.3). A similar risk of SCC (odds ratio=3.2, 95% confidence interval: 2.6, 4.0) was found in heavy smokers after adjustment for HPV16/18 antibodies. The point estimates increased with increasing age at diagnosis and increasing cotinine level. This study confirms that smoking is an independent risk factor for cervical cancer/SCC in women infected with oncogenic HPVs. These findings emphasize the importance of cervical cancer prevention among women exposed to tobacco smoke.

Prevalence of human papillomavirus genotypes in women from a rural region of Puebla, Mexico

OBJECTIVE

To determine the prevalence of human papillomavirus (HPV) genotypes 6, 11, 16, 18, and 31 in Mexican women living in rural areas of Puebla, Mexico and to evaluate risk factors associated with cervical neoplasm in this population.

METHODS

A cross-sectional study was conducted in 326 women at the General Hospital of Metepec, Puebla. Cervical samples were obtained using a cytobrush and tested for HPV genotypes by PCR assays using type-specific primers. A questionnaire was completed regarding gynecological, obstetric, and sexual behavior of the patients.

RESULTS

The overall prevalence of HPV infection was 25.4%, with two peaks of higher HPV prevalence in those aged 18-24 and 55-64 years. The individual genotype prevalences were: 9.6% HPV6, 4.8% HPV11, 54.2% HPV16, 37.3% HPV18, and 9.6% HPV31. Number of pregnancies was the most important risk factor associated with cervical cancer.

CONCLUSIONS

HPV16 was the most common type found in all cervical lesions. Genotype 16 or 18 was detected in patients with a diagnosis of cervical cancer. We found two peaks of age-specific HPV prevalence similar to findings reported worldwide.

Risk factors for human papillomavirus exposure and co-factors for cervical cancer in Latin America and the Caribbean

The incidence of cervical cancer in Latin America and the Caribbean (LAC) is among the highest in the world. Because there are major demographic shifts happening in LAC countries (population growth, urbanization and ageing) cervical cancer incidence and mortality will likely continue to be a significant public health problem. Overall human papillomavirus (HPV) prevalence in the LAC general population has been found to be 2-fold higher than the average worldwide prevalence. The large HPV and cancer burden may be explained by the highly prevalent HPV variants of HPV types -16 and 18, which have an increased oncogenic potential. Given the major mode of transmission of genital HPV is sexual, certain, patterns of sexual behaviour (early age at first sexual intercourse, number of sexual partners and sexual behaviour of the partner) are associated with an increased risk of HPV genital acquisition. Although HPV infection is necessary for carcinogenesis, certain co-factors (high parity, long term use of oral contraceptives, smoking and co-infection with the human immunodeficiency virus (HIV)) help in the progression from infection to cancer. Many studies that have contributed to this evidence have been carried out in LAC and are reviewed and summarised in this article. Since HPV vaccines will likely take years to implement, and many more years to show impact on disease, cervical cancer screening programmes remain as the key intervention to control disease in LAC in the years to come.

Persistence and clearance of human papillomavirus infection: a prospective cohort study

OBJECTIVE

The objective of the study was to identify epidemiological correlates for persistence and clearance of human papillomavirus (HPV) infection.

STUDY DESIGN

Cervical smears collected in a prospective cohort study to perform Papanicoloau cytology and HPV deoxyribonucleic acid (DNA) detection at baseline and during the follow-up. Outcomes analyzed were: (1) persistence of HPV DNA; (2) conversion; and (3) clearance of HPV.

RESULTS

Among 501 women the incidence of HPV was 12.3%. Thirty-four women were persistently infected with HPV, which was associated with age below 21 years at first intercourse and 4 or more sexual partners during their lifetime. In a median of 19 months, 80.7% of women had clearance of HPV, which was associated with black race, coinfection with Chlamydia trachomatis at baseline, and a history of previous Papanicoloau smear.

CONCLUSION

Strategies for sexual orientation may modify the rates of HPV persistence. The association of HPV clearance with a history of previous Papanicolaou smear screening highlights the importance of improving cervical screening programs. Further studies on the association of gynecological infections with HPV clearance are needed.

Descriptive evidence that risk profiles for cervical intraepithelial neoplasia 1, 2, and 3 are unique

OBJECTIVE

This study aimed to estimate if risk factor profiles for histologically confirmed cervical intraepithelial neoplasia (CIN) 2 lesions differ from those for CIN 1 or 3.

METHODS

A total of 2,055 women positive for high-risk human papillomavirus, with a minimum of five cervical biopsies, were enrolled in the Shanxi Province Cervical Cancer Screening Study II. We evaluated risk factor profiles for CIN 2 in comparison with CIN 1 and 3. Polytomous logistic regression was used to generate odds ratios and corresponding 95% confidence intervals and to test for differences in odds ratios across histologic grades.

RESULTS

The risk for CIN 3 associated with three or more pregnancies and sexual intercourse within 4 months of childbirth was higher than that for CIN 2 (P(difference) = 0.02 and 0.0007, respectively). Significant differences in the associations of age groups with CIN 1 and 2 were observed, such that there were positive associations with CIN 2 but none for CIN 1. There was no difference in the association of number of sexual partners or reported number of abortions between CIN 1 and 2 or between CIN 3 and 2.

CONCLUSIONS

In our study, the patterns of risk factor profiles for CIN 1, 2, and 3 were unique. Conventional grouping of CIN 2 with 3 for analysis of risk factors may need revisiting.

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

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

Age at menarche is not an independent risk factor for high-risk human papillomavirus infections and cervical intraepithelial neoplasia

Data are controversial as to the role of menarche age as a risk factor of high-risk human papillomavirus (HR-HPV) infections. The objective of this study was to analyse the risk estimates for age at menarche as determinant of cervical intraepithelial neoplasia (CIN) and HR-HPV infections. A cohort of 3187 women were stratified into three groups according to their age at menarche: (i) women <13 years of age; (ii) those between 13 and 14 years and (iii) women >15 years of age. These groups were analysed for predictors of (a) HR-HPV, (b) high-grade CIN and (c) outcome of HR-HPV and cytological abnormalities during prospective follow-up. All the three groups had identical prevalence of HR-HPV, Papanicolaou smear abnormalities and CIN grades. In contrast to menarche age itself, the time from menarche to the first intercourse (TMI), to the first pregnancy (TMP) and to the first delivery (TMD) were all significant ( P = 0.0001) predictors of HR-HPV (but not CIN2) in univariate analysis, but lost their significance in a multivariate model. Outcome of cervical disease and HR-HPV infection was unrelated to menarche age, the latter and the three intervals being not predictors of CIN2 in a multivariate model. In conclusion, age at menarche and the intervals between menarche and (i) onset of sexual activity, (ii) first pregnancy and iii) first delivery, are not independent predictors of HR-HPV infections and CIN2 in multivariate analysis.

Cervical cancer and hormonal contraceptives: collaborative reanalysis of individual data for 16,573 women with cervical cancer and 35,509 women without cervical cancer from 24 epidemiological studies

BACKGROUND

Combined oral contraceptives are classified by the International Agency for Research on Cancer as a cause of cervical cancer. As the incidence of cervical cancer increases with age, the public-health implications of this association depend largely on the persistence of effects long after use of oral contraceptives has ceased. Information from 24 studies worldwide is pooled here to investigate the association between cervical carcinoma and pattern of oral contraceptive use.

METHODS

Individual data for 16,573 women with cervical cancer and 35,509 without cervical cancer were reanalysed centrally. Relative risks of cervical cancer were estimated by conditional logistic regression, stratifying by study, age, number of sexual partners, age at first intercourse, parity, smoking, and screening.

FINDINGS

Among current users of oral contraceptives the risk of invasive cervical cancer increased with increasing duration of use (relative risk for 5 or more years' use versus never use, 1.90 [95% CI 1.69-2.13]). The risk declined after use ceased, and by 10 or more years had returned to that of never users. A similar pattern of risk was seen both for invasive and in-situ cancer, and in women who tested positive for high-risk human papillomavirus. Relative risk did not vary substantially between women with different characteristics.

INTERPRETATION

The relative risk of cervical cancer is increased in current users of oral contraceptives and declines after use ceases. 10 years' use of oral contraceptives from around age 20 to 30 years is estimated to increase the cumulative incidence of invasive cervical cancer by age 50 from 7.3 to 8.3 per 1000 in less developed countries and from 3.8 to 4.5 per 1000 in more developed countries.

Smoking is an independent risk factor for oncogenic human papillomavirus (HPV) infections but not for high-grade CIN

BACKGROUND

Recent evidence implicates smoking as a risk factor for cervical cancer (CC), but the confounding from high-risk human papillomavirus (HPV) infections is not clear.

OBJECTIVES

To analyse the role of smoking as an independent predictor of CIN2+ and HR-HPV infections in a population-based prospective (NIS, New Independent States of former Soviet Union) cohort study.

STUDY DESIGN AND METHODS

A cohort of 3,187 women was stratified into three groups according to their smoking status: (i) women who never smoked; (ii) those smoking in the past; and (iii) women who are current smokers. These groups were analysed for predictors of (a) HR-HPV; (b) high-grade CIN, and (c) outcome of HR-HPV infections and cytological abnormalities during prospective follow-up (n = 854).

RESULTS

The three groups were significantly different in all major indicators or risk sexual behaviour (or history) implicating strong confounding. There was no increase in HSIL/LSIL/ASC-US cytology or CIN1+/CIN2+/CIN3+ among current smokers. Only few predictors of HR-HPV and CIN2+ were common to all three groups, indicating strong interference of the smoking status. There was no difference in outcomes of cervical disease or HR-HPV infections between the three groups. In multivariate model, being current smoker was one of the five independent predictors of HR-HPV (P = 0.014), with adjusted OR = 1.52 (95%CI 1.09-2.14). In addition to age, HR-HPV was the only independent predictor of CIN2+ in multivariate model (OR = 14.8; 95%CI 1.72-127.31).

CONCLUSIONS

These data indicate that cigarette smoking is not an independent risk factor of CIN2+, but the increased risk ascribed to smoking is mediated by acquisition of HR-HPV, of which current smoking was an independent predictor in multivariate model.

The oncogenic potential of human papillomaviruses: a review on the role of host genetics and environmental cofactors

Human papillomaviruses (HPVs), with over 100 genotypes, are a very complex group of human pathogenic viruses. In most cases, HPV infection results in benign epithelial proliferations (verrucae). However, oncogenic types of HPV may induce malignant transformation in the presence of cofactors. For example, over 99% of all cervical cancers and a majority of vulval, vaginal, anal and penile cancers are the result of oncogenic HPV types. Such HPV types have been increasingly linked to other epithelial cancers involving the skin, larynx and oesophagus. Although viral infection is necessary for neoplastic transformation, evidence suggests that host and environmental cofactors are also required. Research investigating HPV oncogenesis is complex and quite extensive. The inability to produce mature HPV virions in animal models has been a major limitation in fully elucidating the oncogenic potential and role of associated cofactors in promoting malignant transformation in HPV-infected cells. We have reviewed the literature and provide a brief account of the current understanding of HPV oncogenesis, emphasizing the role of genetic susceptibility, immune response, and environmental and infectious cofactors.

Carcinoma of the cervix and tobacco smoking: collaborative reanalysis of individual data on 13,541 women with carcinoma of the cervix and 23,017 women without carcinoma of the cervix from 23 epidemiological studies

Tobacco smoking has been classified as a cause of cervical cancer, but the effect of different patterns of smoking on risk is unclear. The International Collaboration of Epidemiological Studies of Cervical Cancer has brought together and combined individual data on 13,541 women with and 23,017 women without cervical carcinoma, from 23 epidemiological studies. Relative risks (RRs) and 95% confidence intervals (CIs) of carcinoma of the cervix in relation to tobacco smoking were calculated with stratification by study, age, sexual partners, age at first intercourse, oral contraceptive use and parity. Current smokers had a significantly increased risk of squamous cell carcinoma of the cervix compared to never smokers (RR = 1.60 (95% CI: 1.48-1.73), p<0.001). There was increased risk for past smokers also, though to a lesser extent (RR = 1.12 (1.01-1.25)), and there was no clear trend with time since stopping smoking (p-trend = 0.6). There was no association between smoking and adenocarcinoma of the cervix (RR = 0.89 (0.74-1.06) and 0.89 (0.72-1.10) for current and past smokers respectively), and the differences between the RRs for smoking and squamous cell and adenocarcinoma were statistically significant (current smoking p<0.001 and past smoking p = 0.01). In current smokers, the RR of squamous cell carcinoma increased with increasing number of cigarettes smoked per day and also with younger age at starting smoking (p<0.001 for each trend), but not with duration of smoking (p-trend = 0.3). Eight of the studies had tested women for cervical HPV-DNA, and in analyses restricted to women who tested positive, there was a significantly increased risk in current compared to never smokers for squamous cell carcinoma (RR = 1.95 (1.43-2.65)), but not for adenocarcinoma (RR = 1.06 (0.14-7.96)). In summary, smokers are at an increased risk of squamous cell but not of adenocarcinoma of the cervix. The risk of squamous cell carcinoma increases in current smokers with the number of cigarettes smoked per day and with younger age at starting smoking.

Polycyclic aromatic hydrocarbon-DNA adducts in cervix of women infected with carcinogenic human papillomavirus types: an immunohistochemistry study

Among women infected with carcinogenic human papillomavirus (HPV), there is a two- to five-fold increased risk of cervical precancer and cancer in women who smoke compared to those who do not smoke. Because tobacco smoke contains carcinogenic polycyclic aromatic hydrocarbons (PAHs), it was of interest to examine human cervical tissue for PAH-DNA adduct formation. Here, we measured PAH-DNA adduct formation in cervical biopsies collected in follow-up among women who tested positive for carcinogenic HPV at baseline. A semi-quantitative immunohistochemistry (IHC) method using antiserum elicited against DNA modified with r7,t8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) was used to measure nuclear PAH-DNA adduct formation. Cultured human cervical keratinocytes exposed to 0, 0.153, or 0.331microM BPDE showed dose-dependent increases in r7,t8,t9-trihydroxy-c-10-(N(2)deoxyguanosyl)-7,8,9,10-tetrahydro-benzo[a]pyrene (BPdG) adducts. For BPdG adduct analysis, paraffin-embedded keratinocytes were stained by IHC with analysis of nuclear color intensity by Automated Cellular Imaging System (ACIS) and, in parallel cultures, extracted DNA was assayed by quantitative BPDE-DNA chemiluminescence immunoassay (CIA). For paraffin-embedded samples from carcinogenic HPV-infected women, normal-appearing cervical squamous epithelium suitable for scoring was found in samples from 75 of the 114 individuals, including 29 cases of cervical precancer or cancer and 46 controls. With a lower limit of detection of 20 adducts/10(8) nucleotides, detectable PAH-DNA adduct values ranged from 25 to 191/10(8) nucleotides, with a median of 75/10(8) nucleotides. PAH-DNA adduct values above 150/10(8) nucleotides were found in eight samples, and in three samples adducts were non-detectable. There was no correlation between PAH-DNA adduct formation and either smoking or case status. Therefore, PAH-DNA adduct formation as measured by this methodology did not appear related to the increased risk of cervical precancer and cancer among carcinogenic HPV-infected smokers.

A built-in co-carcinogenic effect due to viruses involved in latent or persistent infections

A new hypothesis for some cancers, which combines the chromosomal instability theories with a co-carcinogenic effect of viruses causing latent or persistent infection, is presented. The hypothesis incorporates the multi-step model of cancer and that pre-cancerous cells reach a state of chromosomal instability. Because of chromosomal instability, the genome of these cell lines will lead to changes from generation to generation and will face a remarkable selection pressure both from lost traits, apoptosis, and from the immune system. Viruses causing latent or persistent infections have evolved many different genes capable to evade the immune system. If these viruses are harboured in the genome of pre-cancerous cells they could provide them with "superpowers" and with genes that may assist the cells to elude the immune system. The theory explains why cancer predominantly is a disease of old age. Upon aging, the immune system becomes reduced including the ability to control and suppress the viruses that cause latent or persistent infections. The risk of cancer could thereby increase as the immune functions decrease. The theory provides new insights to the genesis of cancers.

The effect of lifestyle factors on gynaecological cancer

Several lifestyle factors affect a woman's risk of gynaecological cancer and-potentially-can be modified to reduce risk. This chapter summarises the evidence for the effect of lifestyle factors on the incidence of gynaecological malignancy. The incidence of obesity is increasing in the developed world such that it now contributes as much as smoking to overall cancer deaths. Women with a body mass index (BMI)>40 have a 60% higher risk of dying from all cancers than women of normal weight. They are also at increased risk from gynaecological cancer. Dietary factors significantly influence the risk of gynaecological cancer: fruit, vegetables and antioxidants reduce risk whereas high animal fat and energy intakes increase risk. Alcohol intake adversely affects breast cancer risk, possibly accounting for 4% of all breast cancers. Physical activity protects against ovarian, endometrial and postmenopausal breast cancer, independently of BMI. The oral contraceptive pill has a substantial and long-lasting effect on the prevention of ovarian and endometrial cancer and is one of the best examples of large-scale chemoprevention in the developed world. Childbearing is protective against ovarian, endometrial and breast cancer but increases the risk of cervical cancer. Smoking acts as a cofactor in cervical carcinogenesis and increases the risk of ovarian cancer, particularly mucinous tumours.

Human papillomavirus: the burden of infection

Vaccines for preventing human papillomavirus (HPV) infection are far along in clinical development and testing, and hold great promise for reducing HPV infections and HPV-associated disease. HPV is the most common sexually transmitted infection in the United States, affecting an estimated 75% of the U.S. population. HPV infection is highly prevalent in sexually active adolescents and young adults. Sexual activity is the most important risk factor for infection, with 64% to 82% of sexually active adolescent girls testing positive for HPV. Clinical manifestations of HPV infection include genital warts, cervical intraepithelial neoplasia (CIN), and invasive cervical cancer, all of which cause significant morbidity and, in the case of cervical cancer, mortality. The majority of HPV-associated disease is caused by 4 HPV types: HPV 6 and 11 are responsible for low-grade genital lesions and more than 90% of genital warts, and HPV 16 and 18 both account for approximately 70% of all high-grade CIN or dysplasia and invasive cervical cancer. Although current screening methods have proven effective in reducing cervical cancer incidence and associated mortality, more than 10,000 women are diagnosed annually and 4000 U.S. women die from the disease each year.

Reproductive Factors, Oral Contraceptive Use, and Human Papillomavirus Infection: Pooled Analysis of the IARC HPV Prevalence Surveys

High parity, early age at first full-term pregnancy (FTP), and long-term oral contraceptive (OC) use increase cervical cancer risk, but it is unclear whether these variables are also associated with increased risk of acquisition and persistence of human papillomavirus (HPV) infection, the main cause of cervical cancer. Information on reproductive and menstrual characteristics and OC use were collected from 14 areas worldwide, among population-based, age-stratified random samples of women aged 15 years or older. HPV testing was done using PCR-based enzyme immunoassay. Unconditional logistic regression was used to estimate the odds ratios (OR) of being HPV-positive according to reproductive and menstrual factors and corresponding 95% confidence intervals (CI). When more than two groups were compared, floating CIs (FCI) were estimated. A total of 15,145 women (mean age, 40.9 years) were analyzed. Women with >or=5 FTPs (OR, 0.90; 95% FCI, 0.76-1.06) showed a similar risk of being HPV-positive compared with women with only one FTP (OR, 1.00; 95% FCI, 0.86-1.16). However, nulliparous women showed an OR of 1.40 (95% CI, 1.16-1.69) compared with parous women. Early age at first FTP was not significantly related to HPV positivity. HPV positivity was similar for women who reported >or=10 years of use of OCs (OR, 1.16; 95% FCI, 0.85-1.58) and never users of OCs (OR, 1.00; 95% FCI, 0.90-1.12). Our study suggests, therefore, that high parity, early age at first FTP, and long-term OC use are not associated with HPV prevalence, but rather these factors might be involved in the transition from HPV infection to neoplastic cervical lesions.