Human papillomavirus types 16 and 33, herpes simplex virus type 2 and other risk factors for cervical cancer in Sichuan Province, China

Association between human herpesvirus infection and cervical carcinoma: a systematic review and meta-analysis

BACKGROUND

Cervical cancer (CC) is one of the most common gynecologic tumors among women around the world. Although the etiological role of human papillomavirus (HPV) in CC is well established, other factors in CC carcinogenesis remains unclear. Here, we performed a systematic review and meta-analysis to explore the association between infections of human herpesvirus (HHVs) and CC risk.

METHODS

Embase and PubMed databases were utilized to search the relevant studies. The revised JBI Critical Appraisal Tool was used to assess the quality of the included studies. Prevalence and odds ratios (ORs) with 95% confidence intervals (CI) were calculated to evaluate the association between viral infection and CC or precancerous cervical lesions (PCL).

RESULTS

Totally 67 eligible studies involving 7 different HHVs were included in meta-analysis. We found an increased risk of CC or PCL that was associated with the overall infection of HHVs (CC, OR = 2.74, 95% CI 2.13-3.53; PCL, OR = 1.95, 95% CI 1.58-2.41). Subgroup analysis showed a trend towards positive correlations between herpes simplex virus type 2 (HSV-2) infection and CC (OR = 3.01, 95% CI 2.24 to 4.04) or PCL (OR = 2.14, 95% CI 1.55 to 2.96), and the same is true between Epstein-Barr virus (EBV) infection and CC (OR = 4.89, 95% CI 2.18 to 10.96) or PCL (OR = 3.55, 95% CI 2.52 to 5.00). However, for HSV-1 and cytomegalovirus (HCMV), there was no association between viral infection and CC or PCL. By contrast, the roles of HHV-6, HHV-7, and Kaposi sarcoma-associated herpesvirus (KSHV) in cervical lesions were unclear due to the limited number of studies.

CONCLUSIONS

This study provided evidence that HHVs infection as a whole increase the risk of CC incidence. In addition, some types of HHVs such as EBV and HSV-2 may serve as potential targets in the development of new interventions or therapeutic strategies for cervical lesions.

Risk factors for cervical cancer in women in China: A meta-model

Objectives:

Cervical cancer is a leading cause of cancer-related mortality in women in China. This analysis is a quantitative evidence synthesis pooling information about each cervical cancer risk factor.

Methods:

A meta-model was developed to estimate the risk of cervical cancer for a woman aged 18–85 years in Mainland China based on her risk profile at the time of assessment. The meta-model was built using findings of a systematic literature review that identified 21 case–control studies reporting data on 105 groups of cervical cancer risk factors in Chinese women. Extracted risk factors were ranked, and 17 were selected by Chinese clinical experts for inclusion in the meta-model. Risk equations were developed for each selected study. Predicted risks for each study were dependent on the risk profile under consideration and study-specific risks were pooled to an overall risk estimate using a random-effects meta-analysis. Sensitivity analysis was conducted using 100 artificial patient profiles (in the absence of patient data).

Results:

Predicted risks for the 100 profiles suggested that the model had good face validity and could differentiate between high and non-high cervical cancer risk profiles.

Conclusion:

This innovative meta-model approach assesses cervical cancer risk in Chinese women from a holistic perspective and could be adapted for other diseases and settings.

Systematic literature review of risk factors for cervical cancer in the Chinese population

Objectives:

Human papillomavirus is the necessary cause of cervical cancer, in particular the human papillomavirus-16/18 strains, which have been detected in ~70% of all cervical cancer cases worldwide. This study aims to assess whether other cofactors, which might be specific for the Chinese population, are involved in the development of cervical cancer. These findings may support the future direction of cervical cancer prevention.

Study Design:

Systematic literature review.

Methods:

The following databases were searched: MEDLINE, MEDLINE-IN-PROCESS, EMBASE, China National Knowledge Infrastructure, Wanfang Data and Chongqing VIP Information. The target population were adolescents or adults from mainland China. All observational studies irrespective of intervention or comparator reporting risk factors for cervical cancer were included. The Newcastle-Ottawa Scale was used to assess study quality. The impact of each outcome was reported in numerical terms.

Results:

A total of 2,676 articles were screened. A total of 21 articles met the inclusion criteria. All studies were case-controlled designs mostly conducted in hospitals of South-Eastern China. A total of 18 studies reported lifestyle behaviours as significant influencing factors in the development of cervical cancer. Sexual behaviour, gestational factors, screening history, disease history and socio-demographics status were reported as significant risk factors for cervical cancer development.

Conclusion:

This review provides an up-to-date insight of current cervical cancer risk factors in China. Due to the heterogeneity of the results, further evaluation is recommended to determine the association of these risk factors to the overall risk of cervical cancer.

Seropositivity to herpes simplex virus type 2, but not type 1 is associated with cervical cancer: NHANES (1999-2014)

BACKGROUND

Herpes simplex virus types 1 and 2 (HSV1 and HSV2) are infectious agents, and their association with cancer occurrence in human is a controversial topic for decades. We addressed this subject using all available continuous National Health and Nutrition Examination Survey (NHANES) cross-sectional data from 1999 to 2014.

METHODS

Eight data cycles (1999-2000, 2001-2002, 2003-2004, 2005-2006, 2007-2008, 2009-2010, 2011-2012, and 2013-2014) were employed, and a sample of 8184 female participants was used in this study according to the availability of cancer history and HSV serostatus.

RESULTS

The seroprevalences of HSV1 and HSV2 were 60.73 ± 0.89 and 25.02 ± 0.64, respectively, and the numbers increased with age (P < 0.01). In confounder-adjusted logistic regression analysis, association between HSV1 seropositivity and uterine cancer was identified (adjusted odds ratio-OR_adjusted = 6.03; 95% CI: 1.52, 23.87). HSV2 seropositivity was associated with cancer occurrence (OR_adjusted = 1.47; 95% CI: 1.01, 2.14), cervical cancer (OR_adjusted = 1.72; 95% CI: 1.06, 2.79) and uterine cancer (OR_adjusted = 3.49; 95% CI: 1.03, 11.85). Moreover, HSV2 was persistently associated with cervical cancer after further adjusting high-risk human papillomavirus (HPV) as confounder (OR_adjusted = 1.90; 95% CI: 1.09, 3.34). Relative risk (RR)-based interaction measurement between HSV2 and HPV on the additive scale suggests higher RR for cervical cancer in participants with seropositivity for HPV only (RR_adjusted = 2.98; 95% CI: 1.23, 7.20; P = 0.02), HSV2 only (RR_adjusted = 2.79; 95% CI: 1.31, 5.96; P = 0.01) or both viruses (RR_adjusted = 3.44; 95% CI: 1.50, 7.86; P < 0.01) when setting participants with seronegativity for both HPV and HSV2 as reference.

CONCLUSIONS

The finding of current study provides epidemiological evidence that serostatus of HSV2 can serve as an independent predictor for cervical cancer.

HPV and cofactors for invasive cervical cancer in Morocco: a multicentre case-control study

Background

Limited national information is available in Morocco on the prevalence and distribution of HPV-sub-types of cervical cancer and the role of other risk factors. The aim was to determine the frequency of HPV-sub-types of cervical cancer in Morocco and investigate risk factors for this disease.

Methods

Between November 2009 and April 2012 a multicentre case-control study was carried out. A total of 144 cases of cervical cancer and 288 age-matched controls were included. Odds-ratios and corresponding confidence-intervals were computed by conditional logistic regression models.

Results

Current HPV infection was detected in 92.5% of cases and 13.9% of controls. HPV16 was the most common type for both cases and controls. Very strong associations between HPV-sub-types and cervical cancer were observed: total-HPV (OR = 39), HPV16 (OR = 49), HPV18 (OR = 31), and multiple infections (OR = 13). Education, high parity, sexual intercourse during menstruation, history of sexually transmitted infections, and husband’s multiple sexual partners were also significantly associated with cervical cancer in the multivariate analysis.

Conclusions

Our results could be used to establish a primary prevention program and to prioritize limited screening to women who have specific characteristics that may put them at an increased risk of cervical cancer.

Effect of HSV-2 Infection on the Expression of HPV 16 Genes in Caski Cells

Human papillomaviruses (HPVs) have been proposed to be the most important etiological factors for cervical cancer although different agents may act in conjunction. Herpes simplex virus type 2 (HSV-2) infection is considered as a possible cofactor to malignant transformation. To examine the influence of HSV-2 infection on the HPV genes expression, CaSki cells bearing 60 to 600 copies of HPV-16 DNA per cell were used as a model system. Twenty hours post HSV-2 infection the mRNA transcripts for HPV-16 early (E1, E2 and E6) and late (L1) genes were analysed by RT-PCR assay. Results indicated that the level of transcription of E1, E2 and E6 genes was up to 3-fold enhanced in HSV-2 infected CaSki cells suggesting that HSV-2 infection could increase the risk of cervical cancer by overexpression of both HPV regulatory and oncogenic genes.

Herpes simplex virus type 2 and the risk of cervical cancer: a meta-analysis of observational studies

OBJECTIVES

To assess whether herpes simplex virus type 2 (HSV-2) infection has an effect on the risk of cervical cancer.

METHODS

A systematic literature search of PubMed, Embase, Web of Science, and Scopus from their inception through July 2013 was conducted and reference lists of retrieved articles were reviewed. Information on the characteristics of the included studies, risk estimates, and control for possible confounding factors was extracted independently by two investigators. A random effects model was used to calculate the pooled risk estimates.

MAIN RESULTS

Sixteen articles with 20 studies (14 case control and 6 longitudinal) involving 3,337 patients with cervical cancer were included. Compared with individuals who did not experience HSV-2 infection, the pooled ORs of cervical cancer for individuals with HSV-2 infection were 1.37 (95 % CI 1.12-1.69) for traditional case-control studies and 1.04 (95 % CI 0.82-1.31) for prospective or retrospective nested case-control studies.

CONCLUSIONS

Given that a longitudinal study gives a higher level of evidence than a traditional case-control study, the existing observational epidemiological evidence do not support a harmful effect of HSV-2 infection on cervical cancer.

Relationship between cervical disease and infection with human papillomavirus types 16 and 18, and herpes simplex virus 1 and 2

Persistent infection with high-risk HPV, particularly Type HPV 16 and 18, is necessary in the development of cervical cancer, but apart from HPV infection, other causative factors of most cervical cancers remain unknown. The aim of this study was to determine the prevalence of HPV 16 and HPV 18 and HSV 1 and HSV 2 in cervical samples, and to assess the role of HSVs in cervical carcinogenesis. Two hundred thirty-three healthy controls and 567 cases (333 of cervicitis, 210 of cervical intraepithelial neoplasia, and 24 of squamous cell carcinoma) in cervical exfoliative cells were tested for HPV 16, HPV 18, HSV 1, and HSV 2 DNA using the triplex real-time polymerase chain reaction method. In contrast to healthy women, positive rate of HPV is related significantly to cervical lesions (odds ratios (ORs) = 4.1, P < 0.01 for cervical intraepithelial neoplasia; ORs = 24.9, P < 0.01 for squamous cell carcinoma), but not cervicitis (ORs = 2.3, P > 0.05). HSV 2 prevalence in cervical intraepithelial neoplasia and squamous cell carcinoma was higher than in healthy women (ORs = 4.9, P < 0.05 for cervical intraepithelial neoplasia; ORs = 4.7, P < 0.05 for squamous cell carcinoma). HSV 2 coinfection with HPV in cervical intraepithelial neoplasia and squamous cell carcinoma was strongly higher than in healthy women (ORs = 34.2, P < 0.01 for cervical intraepithelial neoplasia; ORs = 61.1, P < 0.01 for squamous cell carcinoma). The obtained results indicated that the presence of HPV is associated closely with cervical cancer, and that HSV 2 infection or co-infection with HPV might be involved in cervical cancer development, while HSV 1 might not be involved.

A novel multiplex real-time PCR assay for the detection and quantification of HPV16/18 and HSV1/2 in cervical cancer screening

Infection with human papillomavirus (HPV), particularly HPV16 and HPV18, is the main cause of invasive cervical cancer, although other factors such as herpes simplex virus (HSV) may act in conjunction with HPV in this context. To explore the possibility of developing a system for rapid diagnosis and clinical screening of cervical cancer, we developed a multiplex real-time PCR assay that can simultaneously detect and quantify HPV16/18 and HSV1/2. To evaluate its possibilities and practical uses, 177 samples collected from patients with suspected HPV and HSV infection in exfoliated cervical cells, genital herpes or labial herpes were tested by multiplex real-time PCR and compared with results obtained by DNA sequencing. Each virus was detected over a range from 1.0 × 10(1) to 1.0 × 10(7) copies/reaction. The clinical sensitivity was 100% for HPV16/18 and HSV1/2. The clinical specificity was 97.1% for HPV16, 98.1% for HPV18, 97.0% for HSV1 and 96.0% for HSV2. The kappa value was 0.96 for HPV16, 0.92 for HPV18, 0.94 for HSV1 and 0.93 for HSV2, when DNA sequencing was used as the reference standard. In summary, this novel multiplex real-time PCR allows the rapid and specific detection of HPV16/18 and HSV1/2, as well as coinfection with HPV and HSV, in clinical samples. In the future, this multiplex real-time PCR assay will assist in cervical cancer screening, viral treatment evaluation and epidemiological studies in which high throughput analysis is required.

Human papillomavirus infection in Honduran women with cervical intraepithelial neoplasia or cervical cancer

OBJECTIVES

The aims of this study were to investigate human papillomavirus (HPV) genotypes in women with cervical intraepithelial lesions and cervical cancer (CC) in Honduras and to identify epidemiological cofactors that contribute to the development of CC.

METHODS

Among the 289 patients analyzed, 139 had low-grade squamous intraepithelial lesion (LSIL), 60 had high-grade squamous intraepithelial lesion (HSIL), and 90 had CC.

RESULTS

The HPV DNA was detected in 113 women (81%) with LSIL, in 58 women (97%) with HSIL, and in 84 women (93%) with CC. Twenty-five HPV genotypes were found. Human papillomavirus type 16 was detected in 41% of women with CC, in 35% of women with HSIL, and in 24% of women with LSIL. Human papillomavirus type 18 was found in 9% of women with CC, in 4% of women with HSIL, and 5% of women with LSIL.

CONCLUSION

Therefore, implementation of the prophylactic vaccines against HPV genotypes 16 and 18 has the potential of preventing at least a quarter of LSIL, one third of HSIL, and about half of CC cases in Honduras.

Invited commentary: Human papillomavirus infection and risk of cervical precancer--using the right methods to answer the right questions

Epidemiologists are well aware of the negative consequences of measurement error in exposure and outcome variables to their ability to detect putative causal associations. However, empirical proof that remedying the misclassification problem improves estimates of epidemiologic effect is seldom examined in detail. Of all areas in cancer epidemiology, perhaps the best example of the consequences of misclassification and of the steps taken to circumvent them was the pursuit, beginning in the mid-1980s, of the human papillomavirus (HPV) infection-cervical cancer association. The stakes were high: Had the wrong conclusions been reached epidemiologists would have been led astray in the search for competing hypotheses for the sexually transmissible agent causing cervical cancer or in ascribing to HPV infection a mere ancillary role among many lifestyle, hormonal, and environmental factors. The article by Castle et al. in this issue of the Journal (Am J Epidemiol. 2010;171(2):155-163) provides a detailed account of the joint influences of improved HPV and cervical precancer measurements in gradually unveiling the strong magnitude of the underlying association between viral exposure and cervical lesion risk. In this commentary, the authors extend the findings of Castle et al. by providing additional empirical evidence in support of their arguments.

Human papillomavirus type-distribution in cervical cancer in China: the importance of HPV 16 and 18

Prophylactic vaccination against HPV 16 and 18 has the potential for effective prevention of high-grade precancer (cervical intraepithelial neoplasia [CIN)] 2/3) and ICC caused by these viruses (globally 50 and 70%, respectively) when employed in women prior to starting sexual activity. To provide data for decisions on HPV vaccination in China, we determined HPV type-distribution in ICC and CIN 2/3 from women of different regions within China. A multicenter study was conducted by randomized sampling of paraffin blocks of 664 ICC (630 squamous cell carcinoma [SCC]; 34 adenocarcinoma [ADC]), 569 CIN 2/3 cases from seven regions of China. Histological diagnosis was confirmed in 1,233 cases by consensus review. HPV DNA was detected using the SPF10 LiPA25 version 1 assay. HPV prevalence was 97.6% in SCC, 85.3% in adenocarcinoma, and 98.9% in CIN 2/3. HPV 16 (76.7%) and HPV 18 (7.8%) were the most common, together accounting for 84.5% of SCC, followed by HPV 31 (3.2%), HPV 52 (2.2%), and HPV 58 (2.2%). HPV positivity in SCC did not differ notably by region. However, SCC cases from women <or=34 years had higher HPV 16 positivity than women over 50 years, among whom HPV 52, 58, and 39 were more common. HPV 16 and 18 were under-represented, whereas HPV 31, 52, and 58 were over-represented in CIN2/3 compared to SCC. The potential impact of vaccines against oncogenic HPV types 16 and 18 is estimated to be high (84.5%) against total SCC. These data are critical for China's future evaluation of the cost-effectiveness of current cervical cancer vaccines and of HPV-based screening guidelines.

Age-specific prevalence of infection with human papillomavirus in females: a global review

PURPOSE

Global data on age-specific prevalence of human papillomavirus (HPV) infection overall, and for high-risk HPV types 16 and 18, are essential for the future implementation of HPV prophylactic vaccines for cervical cancer prevention.

METHODS

A systematic review of peer-reviewed publications was conducted to summarize worldwide data on genital HPV-DNA prevalence in women. Studies with clear descriptions of polymerase chain reaction or hybrid capture detection assays were included.

RESULTS

A total of 346,160 women were included in 375 studies. Of 134 studies with age-stratified HPV prevalence data (116 low sexual risk populations, 18 high sexual risk populations), over 50% were from Europe and the Middle East (38%) and North America (19%), with smaller proportions from Asia and Australia (21%), Central and South America (11%), and Africa (10%). Across all geographical regions, data on HPV prevalence were generally limited to women over 18 years of age. Consistently across studies, HPV infection prevalence decreased with increasing age from a peak prevalence in younger women (< or =25 years of age). In middle-aged women (35-50 years), maximum HPV prevalence differed across geographical regions: Africa (approximately 20%), Asia/Australia (approximately 15%), Central and South America (approximately 20%), North America (approximately 20%), Southern Europe/Middle East (approximately 15%), and Northern Europe (approximately 15%). Inconsistent trends in HPV prevalence by age were noted in older women, with a decrease or plateau of HPV prevalence in older ages in most studies, whereas others showed an increase of HPV prevalence in older ages. Similar trends of HPV 16 and/or 18 prevalence by age were noted among 12 populations with available data.

DISCUSSION

Genital HPV infection in women is predominantly acquired in adolescence, and peak prevalence in middle-aged women appears to differ across geographical regions. Worldwide variations in HPV prevalence across age appear to largely reflect differences in sexual behavior across geographical regions. Further studies of HPV prevalence in adolescents are needed for all geographic regions.

Human papillomavirus type distribution in women from Asia: a meta-analysis

The aim of this study was to determine human papillomavirus (HPV) type distribution in women with and without cervical neoplasia from Asia and to estimate the potential future impact of an HPV 16/18 prophylactic vaccine in this region. A meta-analysis was conducted including 79 studies using polymerase chain reaction to detect HPV types. A total of 5954, 1653, 958, and 16,803 women with invasive cervical cancer (ICC), high-grade squamous intraepithelial lesions (HSIL), low-grade squamous intraepithelial lesions (LSIL), and normal cytology or histology were included, respectively. Type-specific prevalence of HPV types 6, 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68, 70, 73, and 82 were estimated and stratified by cervical lesion grade. Overall HPV prevalence was 85.9%, 81.0%, 72.9%, and 14.4%, respectively, in women with ICC, HSIL, LSIL, and normal cytology/histology. In ICC, HPV 16 was the predominant type (52.4%), followed by HPV 18, 58, 33, 52, 45, 31, and 35. The estimated HPV 16/18-positive fraction was 66.9%, 40.4%, 26.7%, and 3.3% in women with ICC, HSIL, LSIL, and normal cytology or histology, respectively. In ICC, the estimated HPV 16/18-positive fraction was about 70% in all Asian geographic regions, with the exception of Japan (51.3%). HPV 16/18 vaccines are estimated to provide about 67% protection against ICC in Asia. HPV 58 and 52 were among the five most common types in ICC in eastern and southeastern Asia but not in south central Asia. After HPV 16 and 18, the next most six common HPV types were 58, 33, 52, 45, 31, and 35 that accounted for additional 20% of cervical cancer cases in Asia. For optimal population coverage, these HPV carcinogenic types should be considered for second-generation HPV prophylactic vaccines.

Interactions between human papillomavirus and other sexually transmitted agents in the etiology of cervical cancer

The interplay between human papillomavirus, notably type 16, and HIV in cervical carcinogenesis leads to persistent infection and cervical neoplasia by destruction of the afferent arm (Langerhans cells) of the host immune system. The joint effect takes place at the early stages of squamous intraepithelial lesions and has severe consequences if left untreated. The recent increase of cervical cancer mortality in young women in developed countries may well be a result of the HIV epidemic. Infection with Chlamydia trachomatis is associated with cervical squamous cell carcinoma but not with cervical adenocarcinoma, and the association remains after adjusting for human papillomavirus 16. Joint effects of C. trachomatis and the human papillomaviruses have not been studied at the population level but indirect evidence from epidemiological studies suggests that the interaction might be different (synergistic versus antagonistic) at different stages (cervical intraepithelial neoplasia versus invasive cervical cancer) of cervical carcino-genesis. Concomitant exposure to human papillomaviruses 6 or 11 and human papillomavirus type 16 has not been shown to result in excess risk of cervical squamous cell carcinoma. This antagonistic joint effect was also discovered between human papillomavirus types 18 and 16, as well as 33 and 16. Herpes simplex virus type 2 antibodies are associated with a modest risk of cervical cancer, which is not surprising since the presence of herpes simplex virus antibodies reflects risk-taking sexual behaviour. However, no excess risk remains after adjustment for human papillomavirus type 16, and no interaction between these two viruses has been found in epidemiological studies. Evidence of interaction between human papillomavirus type 16 and the other members of the herpesvirus family is still at an experimental level and difficult to judge. Little progress has been made in the most promising experimental association between the oncogenic human papillomaviruses and adeno-associated viruses. In addition to the well established interaction between human papillomaviruses and HIV, intriguing interactions are emerging between the human papillomaviruses and C. trachomatis, as well as between the different human papillomavirus types.

HPV prevalence, E6 sequence variation and physical state of HPV16 isolates from patients with cervical cancer in Sichuan, China

OBJECTIVES

Infection with high-risk human papillomavirus (hr-HPV) is an important factor associated with cervical cancer. The genetic mutation of HPV16 E6 and integration of HPV16 DNA in the cervical carcinoma tissues are considered important genetic changes in cervical lesion progression. But the studies of hr-HPV epidemiology are relatively less in the area of Sichuan, China. Therefore, we investigated the prevalence of 9 high-risk subtypes and analyzed the genetic mutation characteristic of HPV16 E6 and physical state of HPV16 DNA.

METHODS

The fragments of L1 and E6 genes were amplified by PCR or nested PCR and then directly sequenced. Further, the multiplex PCR for HPV16 E2 and E6 genes was performed for detection of integration.

RESULTS

HPV16, 58 and 18 were prominent, accounting for 78.6%, 20.0% and 9.7%, respectively in 145 isolates. E6 variants revealed that the European (EP) prototype and East Asia (EA) strain were 26 (23.0%) and 34 (30.1%), respectively. Furthermore, there were 14 base substitutions in E6 regions of the study group, of which 12 resulted in amino acid changes and the rest was silent mutation. Significantly, the 240G substitution exactly located the P53 degradation site. Overall, 8 of 114 (7.0%) isolates only contained integrated HPV16 DNA, 43 (37.7%) only contained episomal DNA and 63 (55.3%) contained both integrated and episomal DNA. The proportion of disruption of an intact E2 gene in the patients with cervical cancer is much lower than that in the previous studies.

CONCLUSIONS

HPV16, 58 and 18 were mainly prevailing subtypes in patients with cervical cancer from Sichuan areas, China and EP/EA strains were predominant in these areas. Some mutations of E6 gene, which lead to the amino acid changes, may be more potentially carcinogenic and the proportion of disruption of an intact E2 gene is much lower.

Cross-sectional analysis of oncogenic HPV viral load and cervical intraepithelial neoplasia

In human papillomavirus (HPV)-associated carcinogenesis, HPV infection characteristics such as viral load may play an important role in lesion development. The purpose of this study was to determine the association between quantitative assessment of oncogenic HPV viral load, and abnormal cytology among women residing along the United States-Mexico border. A cross-sectional study of 2,319 women was conducted between 1997 and 1998. Viral load of oncogenic HPV types (16, 18, 31, 39, 45, 51, 52, and 58) was measured among 173 HPV (+) women using quantitative real-time PCR. Overall, HPV 16, 31, 52 and 58 showed the highest viral load. Single type infection had higher viral loads compared to multiple type infections. HPV viral load declined significantly (p = 0.04) with age. No significant association was observed with other known HPV risk factors such as oral contraceptive use, parity, sexual and STD history. Viral load was independently associated with degree of cervical lesions. An adjusted odds ratio (AOR) of 4.7 for the association between increasing total viral load and Atypical Squamous Cells of Undetermined Significance (ASCUS)/Atypical Glandular Cells of Undetermined Significance (AGUS) was observed (p for trend <0.01). Increased risk of low-grade SIL was observed with higher viral load compared with HPV negative women (AOR = 47.7 for total viral load; AOR = 37.1 for HPV viral load not including HPV16, and AOR = 25.9 for HPV16 viral load). Likewise, increased risk of high-grade SIL with higher viral loads was observed (AOR = 58.4 for high total viral load compared with HPV negative women, AOR = 58.1 for HPV viral load not including HPV16, and AOR = 69.8 for HPV16 high viral load). Results from this study suggest a dose-response relationship between increasing oncogenic HPV viral load and risk of LSIL and HSIL.

Time trends in cancer mortality in China: 1987-1999

A first analysis of time trends in cancer mortality in China at the national level is presented. Using a joinpoint regression model, based on data from a national mortality routine reporting system in China (CHIS), time trends in mortality for 9 major cancers are analyzed. Between 1987 and 1999, the age-standardized mortality rates for all cancers combined declined slightly in rural areas but have increased since 1996 in urban areas. The mortality rates for cancers in oesophagus, stomach, cervix uteri, leukaemia (except for urban males after 1996) and nasopharynx declined, while lung cancer and female breast cancer showed significant increasing trends in both urban and rural areas and for both sexes. Cancers of the colon-rectum and liver had different trends in mortality in urban and rural populations. The trends in age-specific mortality rates suggest some different trends in the younger population, which may presage future overall trends, for example, increasing mortality from cancer of the cervix. The observed trends primarily reflect the dramatic changes in socioeconomic circumstances and lifestyles in China in the last 2 decades. Tobacco smoking remains a major problem, with increases in mortality from lung cancer. The improvements in socioeconomic status, diet and nutrition may be responsible for the declining risk of some cancers (oesophagus, stomach and nasopharynx), while increasing the risk for others (breast and colon-rectum). Screening programs (especially for cervix cancer), and more available and better facilities for cancer therapy, may have helped to reduce mortality for several cancers. The large increases in the absolute number of deaths that resulted from the increasing and aging population are much more important in determining the future cancer burden than any changes due to change in risk, emphasizing the increasing importance of cancer as a health problem in the 21st century in China.

The Epidemiology of Cervical Cancer

Cervical cancer is one of the most common neoplastic diseases affecting women, with a combined worldwide incidence of almost half a million new cases annually, second only to breast cancer. Basic and epidemiologic research conducted during the past 15-20 years have provided overwhelming evidence for an etiologic role for infection with certain types of sexually-transmitted human papillomavirus (HPV) as the primary cause of cervical cancer. The relative risks of cervical cancer following HPV infection as ascertained in case-control and cohort studies are among the highest in cancer epidemiology. The available evidence indicates that the HPV-cervical cancer association satisfies all relevant causal criteria for public health action. Other cervical cancer risk factors, such as smoking, parity, use of oral contraceptives, diet, other infections, and host susceptibility traits must be understood in the context of mediation of acquisition of HPV infection or in influencing events of the natural history of cervical neoplasia that occur following the establishment of a persistent HPV infection. Virtually all cervical carcinoma specimens contain HPV DNA, which suggests that HPV infection is a necessary cause of cervical neoplasia. This is the first instance in which a necessary cause has been demonstrated in cancer epidemiology--a realization that has obvious implications for primary and secondary prevention of this neoplastic disease.

Meta-analysis of social inequality and the risk of cervical cancer

Previous studies of the relationship between socio-economic status and cervical cancer have been mainly based on record linkage of routine data, such as cancer registry incidence rates and regional measures of social class based on census data. These routine data are liable to substantial misclassification with respect to socio-economic status. Previous reports are also primarily from developed countries, whereas the major burden of cervical cancer is in developing countries. We have therefore pooled the data from previously reported case-control studies of cervical cancer or dysplasia, which contain individual-level information on socio-economic characteristics to investigate the relationship between cervical cancer, social class, stage of disease, geographical region, age and histological type. Based on 57 studies, we found an increased risk of approximately 100% between high and low social class categories for the development of invasive cervical cancer, and an increased risk of approximately 60% for dysplasia, including carcinoma in situ. Although the difference was observed in all countries, it was stronger in low/middle income countries and in North America than in Europe. No clear differences were observed between squamous cell carcinoma and adenocarcinoma, or between younger and older women. These results indicate that both cervical infection with human papillomavirus, which is linked to both female and male sexual behaviour, and access to adequate cervical cancer screening programmes are likely to be important in explaining the large cervical cancer incidence rates observed in different socio-economic groups, and that the importance of these factors may vary between different geographical regions.

Cigarette smoking and cervical cancer: Part I: a meta-analysis

Cancer of the cervix is the third most common cancer among women worldwide and its etiology is not clearly understood. Human papillomavirus can be found in approximately 95% of cervical cancers, but it does not appear to be necessary or sufficient to induce malignancy. In 1977, Winkelstein suggested that cigarette smoking was a causative factor in the development of cervical cancer. We report a meta-analysis of cigarette smoking and cervical disease and conclude that the data support a role for cigarette smoking as a risk factor for cervical cancer. We propose a multifactorial hypothesis involving a virus-tar interaction as the etiology of cervical cancer.

Age-specific prevalence of infection with herpes simplex virus types 2 and 1: a global review

Information on age- and sex-specific prevalence of herpes simplex virus (HSV) types 2 and 1 infections is essential to optimize genital herpes control strategies, which increase in importance because accumulating data indicate that HSV-2 infection may increase acquisition and transmission of human immunodeficiency virus. This review summarizes data from peer-reviewed publications of type-specific HSV seroepidemiologic surveys. HSV-2 prevalence is, in general, highest in Africa and the Americas, lower in western and southern Europe than in northern Europe and North America, and lowest in Asia. HSV-2 and -1 prevalence, overall and by age, varies markedly by country, region within country, and population subgroup. Age-specific HSV-2 prevalence is usually higher in women than men and in populations with higher risk sexual behavior. HSV-2 prevalence has increased in the United States but national data from other countries are unavailable. HSV-1 infection is acquired during childhood and adolescence and is markedly more widespread than HSV-2 infection. Further studies are needed in many geographic areas.

Prevalence of human papillomavirus in cervical cancer: a multicenter study in China

A large-scale epidemiologic survey on the prevalence of different types of human papillomavirus (HPV) in cervical cancer in China is indicated because of the implications for the development of diagnostic probes and vaccines against cervical cancer. A total of 809 cervical cancer specimens were collected from 5 regions in China including Shanghai, Guangzhou, Sichuan, Beijing and Hong Kong. HPV DNA was detected in 83.7% of the specimens. HPV-16 was present in 79.6%, HPV-18 in 7.5%, HPV-52 in 2.6% and HPV-58 in 3.8% of all HPV-positive specimens. The prevalences of HPV-16 and HPV-18 in Hong Kong were 61.7 and 14.8%, respectively, representing a lower HPV-16 and a higher HPV-18 proportion compared with the other regions. HPV-16 remained the most common HPV infection in both squamous cell carcinoma (SCC) and adenocarcinoma (AC). The proportion of HPV-18 infection was significantly higher in AC than in SCC.

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.

Screening for the major malignancies affecting women: current guidelines

Throughout their lifetimes, many women rely on the obstetrician-gynecologist to provide them with regular health care. Therefore the obstetrician-gynecologist should be able to provide comprehensive information regarding consensus screening recommendations for the major malignancies that occur in women. Additionally, a woman's health care provider should continually refine his or her cancer risk--assessment skills and should remain apprised of high-risk habits, family histories, and other cancer-predisposing factors that allow identification of those women in whom heightened surveillance or intervention may be appropriate. This article reviews the epidemiologic and risk factors associated with the major malignancies that affect women today and provides screening guidelines.

Prevalence and risk factors for herpes simplex virus type 2 infection among middle-age women in Brazil and the Philippines

BACKGROUND

Data comparing type-specific herpes simplex virus type 2 (HSV-2) seroprevalence and risk factors between comparable populations are largely unavailable, particularly from less-developed countries.

GOAL

To examine the seroprevalence of HSV-2 infection and the risk factors for this infection among women in São Paulo, Brazil, and Manila, the Philippines.

STUDY DESIGN

Altogether, 552 middle-aged women participating as control subjects in two cervical cancer studies were screened for type-specific HSV-2 antibodies.

RESULTS

Herpes simplex virus type 2 seroprevalence was higher in Brazil (42%) than in the Philippines (9.2%). The mean ages of Brazilian (n = 181) and Filipino (n = 371) women were 52.4 and 46.6 years, respectively. Brazilian participants had more lifetime sexual partners, less education, and more often a husband with other sexual partners than Filipino women. Herpes simplex virus type 2 was independently associated with younger age at first intercourse in both countries. More than one lifetime sexual partner, a husband with other sexual partners, urban/semi-urban residence, and no history of condom use were HSV-2 risk factors in Brazil, but not in the Philippines, where long-term hormonal contraceptive use was associated with increased risk.

CONCLUSIONS

The higher HSV-2 seroprevalence in Brazil than in the Philippines may be explained largely by differences in the sexual behavior of women and their husbands. Herpes simplex virus type 2 seroprevalence data may be used as a marker of past sexual behavior for the direct comparison of different population groups.

Analysis of mutations in the URR and E6/E7 oncogenes of HPV 16 cervical cancer isolates from central China

High rates of cervical cancer have been reported from parts of China and this may reflect a predominance of cervical infection with particularly aggressive human papillomavirus (HPV) variants. This PCR-based investigation of cervical tumours from Sichuan province in central China demonstrated an HPV positivity rate of 88%. HPV 16 was most common (21/34, 61%), followed by HPV 18 (3/34, 9%), while types 33, 45, 58 and 59 were each identified in one specimen. Sequencing of up to 1349 bases of the 21 HPV 16-positive isolates, encompassing the enhancer/promoter of the upstream regulatory region (URR) and the E6 and E7 genes, revealed distinct patterns of genomic stability and variability. An overall mutation rate of 5% was seen in the URR. One isolate had a large deletion of 436 bases in the enhancer; while varying combinations of 21 point mutations were identified in the remainder, impacting several YY1, NF1, TEF-1 and Oct-1 sites. More sequence variations were found in E6 compared to E7 (81% vs. 52% of isolates showing at least one mutation), some of which resulted in changes to the translated amino acids. Since the E6/E7 genes encode the oncogenic proteins essential for malignant transformation, and as their expression is controlled by the URR, it is possible that some of the identified mutations altered the oncogenicity of the virus: either directly by changing amino acid sequences of the E6 or E7 oncoproteins, or indirectly through alterations to transcription factor binding sites in the URR.

Tubal sterilization and use of an IUD and risk of cervical cancer

The relationship of tubal sterilization and use of an intrauterine device (IUD) to the risk of invasive squamous cell cervical cancer was evaluated in a case-control study carried out in Shandong, China, from 1989 to 1991. Patients (cases) were 272 women aged 30-77 years with newly diagnosed invasive squamous cell cervical cancer in Shandong Province Tumor Hospital. Controls were 893 randomly selected screened women matched to the cases by age (within 2 years) and county. A decrease in risk was observed in uses of an IUD, especially in long-term users under age 33. A nonsignificant decrease in risk in women under age 33 who had had a tubal ligation was also observed, especially in the first 10 years since the procedure. Tubal ligation and IUD insertion and removal provide opportunities to screen women for cervical cancer and reduce the risk of invasive disease.

The viral origin of cervical cancer in Rabat, Morocco

In Northern Africa, cervical cancer is the second most common cancer among women. The diagnosis is usually made in advanced stages, and mortality is high, yet few studies have investigated the role of human papillomavirus (HPV) and other risk factors in the etiology of cervical cancer. A hospital-based case-control study was completed at the Institut National d'Oncologie (INO) in Rabat, Morocco. The study included 214 cases of invasive cervical cancer and 203 controls. A structured questionnaire was used to investigate known and suspected risk factors for cervical cancer. A GP 5+/6+ polymerase chain reaction system was used to detect the presence of HPV DNA and HPV type distribution. Probes for 30 HPV types were used in one research laboratory. HPV DNA was the central risk factor and accounted for the large majority of the cases. The adjusted odds ratio (ORa) for any HPV was 61.6 (95% CI, 29.2-130) and the corresponding HPV attributable fraction (AF) was 92%. Among cases of cervical cancer, HPV 16 was the most common type (67.7%) followed by HPV 18. The HPV type-specific prevalence was similar for squamous cell carcinomas and adenocarcinomas. In multivariate adjusted or HPV-stratified analyses, in addition to the strong effect of HPV, other risk factors identified were sexual intercourse with multiple partners before the age of 20 and low socio-economic status. Use of oral contraceptives for 5 or more years and high parity were also found to be related to cervical cancer. Screening was rare in this population but offered substantial protection against cervical cancer. In Morocco, cervical cancer is a late sequel of a viral infection with certain HPV types. Developing screening programs for preneoplastic cervical lesions is a public health priority. When available, HPV vaccination would offer a relevant alternative for preventing cervical cancer.

Human papillomavirus infection and invasive cervical neoplasia: a study of prevalence and morphology

The prevalence of human papillomavirus (HPV) DNA sequences in 45 cervical cancer biopsies was examined with the hot-start polymerase chain reaction (PCR), employing HPV consensus primers from the L1 region. The cases comprised 38 squamous cell carcinomas, three adenosquamous carcinomas, and four adenocarcinomas. PCR products were typed with single-strand conformation polymorphism (SSCP) and the HPV types detected were correlated with tumour type. Forty-three biopsies were HPV-positive, HPV16 being the most prevalent type. HPV18/33/45/58 were also detected, but no low-risk or multiple types. Keratinizing squamous cell carcinoma was invariably associated with HPV16 and adenosquamous carcinoma and adenocarcinoma with HPVs 18/45. Non-keratinizing squamous cell carcinomas harboured all five detected types. Our data corroborate the view that malignant cervical tumours are almost invariably associated with high-risk HPV and that certain malignant cervical tumour phenotypes correlate with specific HPV types.

Human papillomavirus types 52 and 58 are prevalent in cervical cancers from Chinese women

A substantial body of evidence has confirmed human papillomavirus (HPV) infection as an etiologic agent in human cervical cancer. To evaluate the association between HPV and cervical cancer in Chinese women, we examined tumor specimens from women who lived in Shanghai, People's Republic of China. Biopsies from 40 women, diagnosed with either squamous-cell carcinoma (n = 35) or adenocarcinoma (n = 5) were tested for HPV DNA by PCR. The HPV types present in tumors were determined either by hybridization of PCR products with HPV type-specific probes or by PCR-based sequencing. A total of 35 of the 40 cervical cancer specimens (87.5%) contained HPV DNA. The following distribution and types were detected: 7.5% HPV 16, 10% HPV 18, 20% HPVs 16 and 18, 15% HPV 52, 15% HPV 58, 12.5% HPVs 52 and 58 and 7.5% unclassified HPVs. In this population of Chinese women with cervical cancer, HPV 52 and 58 were as prevalent as the "high-risk" (for cervical cancer) viruses HPVs 16 and 18.

Prevalence of human papillomavirus DNA in cervical tissue. Retrospective analysis of 855 cervical biopsies

The histopathologic features of 855 cervical biopsies were correlated with the presence of human papillomavirus DNA using in situ hybridization (ISH) with biotin labeled type specific probes for Human Papilloma Virus (HPV) types 6, 11, 16, 18, 31, 33 and 51. HPV-DNA was found in 18% (13/72) of cervical intraepithelial neoplasia I (CIN I), 30% (35/115) of CIN II, 28% (57(206) of CIN III, in 84% (21/25) of flat condyloma and in 13% (15/112) of normal cervical tissue. HPV DNA was detectable in 11% (5/46) of cervical adenocarcinoma and in 21% (59/279) of squamous cell carcinoma (SCC) of the cervix. High risk HPV types were identified more often than low risk HPV types in CIN I, CIN II, CIN III and SCC. HPV type 16/18 predominates over HPV types 31/33/51 in CIN I, flat condyloma and in SCC. The prevalence of HPV was strongly associated with the grade of differentiation of SCC. It was identified in 59% (23/39) of well differentiated SCC, in 18% (25/142) of moderately differentiated and in 11% (11/98) of poorly differentiated SCC.

Risk factors for HPV DNA detection in middle-aged women

BACKGROUND AND OBJECTIVES

Strong epidemiologic evidence indicates that human papillomavirus (HPV) is the main etiologic factor of cervical cancer. A few cohort studies suggest that most HPV infections are transient in young women and that persistent HPV infections are more common in older women. Little is known about the determinants of persistent HPV infections. The present study was aimed at increasing our knowledge about these determinants.

GOALS

To identify risk factors for genital HPV DNA detection among cytologically normal middle-aged women.

STUDY DESIGN

Eight hundred ten women who participated as control subjects in three case-control studies on cervical cancer in Spain, Colombia, and Brazil were included in this study. After an interview, women underwent a gynecologic examination with collection of exfoliated cells for a Papanicolaou smear and HPV DNA detection. Human papilloma virus DNA was detected by polymerase chain reaction (PCR)-based hybridization techniques.

RESULTS

The HPV positivity rate was 10.5% in the whole population, but was higher in the areas with high incidence of cervical cancer (17% in Brazil and 13% in Colombia) than in Spain (4.9%), which is a low-risk area for cervical cancer. Age was related to the prevalence of HPV DNA in Brazil, but not in Spain and Colombia. In univariate analyses in all three countries, the prevalence of HPV DNA was positively associated with the number of lifetime sexual partners and inversely associated with the levels of family income and with age at first sexual intercourse. There was four times increase in the odds ratio (OR) of HPV infection in women who had six or more lifetime sexual partners compared with those with one or less. The use of any kind of contraceptive tended to decrease the OR for HPV detection. Their ORs ranged from 0.44 (barrier methods) to 0.48 (oral contraceptives). In Spain and Colombia, antibodies against Chlamydia trachomatis were positively associated with the prevalence of HPV DNA. In a final multivariate model, the positive associations with lifetime number of sexual partners, socioeconomic status, and C. trachomatis persisted.

CONCLUSIONS

These results support the sexual transmission of HPV and suggest that socioeconomic status and antibodies to C. trachomatis are independent predictors of HPV detection in middle-aged cytologically normal women.

Evaluation of the Hybrid Capture human papillomavirus deoxyribonucleic acid detection test

OBJECTIVE

Our purpose was to evaluate the sensitivity and accuracy of a new, nonradioactive human papillomavirus deoxyribonucleic acid detection method.

STUDY DESIGN

Cervical samples from 520 women were assayed for human papillomavirus deoxyribonucleic acid with both the Hybrid Capture test and polymerase chain reaction.

RESULTS

Human papillomavirus deoxyribonucleic acid was detected with Hybrid Capture in 106 (42%) of 254 samples from women with no evidence of cervical intraepithelial neoplasia and 211 (79%) of 266 with cervical intraepithelial lesions or cervical cancer. There was a good correlation between Hybrid Capture and polymerase chain reaction. Hybrid Capture correctly identified 92% of samples found to contain a human papillomavirus type with a high or intermediate oncogenic risk with polymerase chain reaction. Although Hybrid Capture can quantify the amount of human papillomavirus deoxyribonucleic acid present in a sample, no correlation was observed between the relative amount of human papillomavirus deoxyribonucleic acid detected with Hybrid Capture and the grade of cervical lesion.

CONCLUSION

The Hybrid Capture test is a sensitive and accurate method for identifying human papillomavirus types of high and intermediate oncogenic risk in clinical specimens.

Cervical cancer: is herpes simplex virus type II a cofactor?

In many ways, cervical cancer behaves as a sexually transmitted disease. The major risk factors are multiple sexual partners and early onset of sexual activity. Although high-risk types of human papillomaviruses (HPV) play an important role in the development of nearly all cases of cervical cancer, other sexually transmitted infectious agents may be cofactors. Herpes simplex virus type 2 (HSV-2) is transmitted primarily by sexual contact and therefore has been implicated as a risk factor. Several independent studies suggest that HSV-2 infections correlate with a higher than normal incidence of cervical cancer. In contrast, other epidemiological studies have concluded that infection with HSV-2 is not a major risk factor. Two separate transforming domains have been identified within the HSV-2 genome, but continued viral gene expression apparently is not necessary for neoplastic transformation. HSV infections lead to unscheduled cellular DNA synthesis, chromosomal amplifications, and mutations. These observations suggest that HSV-2 is not a typical DNA tumor virus. It is hypothesized that persistent or abortive infections induce permanent genetic alterations that interfere with differentiation of cervical epithelium and subsequently induce abnormal proliferation. Thus, HSV-2 may be a cofactor in some but not all cases of cervical cancer.

Human papillomavirus and cervical neoplasia: a case-control study in Taiwan

As part of a large-scale, community-based cervical neoplasia screening project in rural Taiwan, a case-control study was undertaken to evaluate the etiologic role of human papillomavirus (HPV) infection in this mainly monogamous (2% reported having multiple sexual partners) female population. A total of 88 biopsy-confirmed cases and 261 cytologically normal controls were selected for the study. The case group included 40 cases of cervical intraepithelial neoplasia (CIN) 1, 9 of CIN 2, 36 of CIN 3 and 3 cases of invasive cancer. Cervical swabs collected at screening from study subjects were tested for HPV DNA by an LI consensus primer polymerase chain reaction (PCR)-based technique. HPV DNA was found in 92% of high-grade cases (CIN 2-3 and invasive cancer); 54% of low-grade cases (CIN 1); and 9% of controls. HPV was significantly associated with both high-grade and low-grade cervical neoplasia. As reported in Western countries, HPV 16 was the predominant type among HPV-positive high-grade cases. However, HPVs 52 and/or 58 combined were the most common types among HPV-positive low-grade cases and controls. Among women without any high-risk HPV infection (types 16, 18, 31 or 45), those with multiple-type HPV infection had a higher risk for high-grade cervical neoplasia than those with single-type infection. Overall, 91% of high-grade cases and 50% of low-grade cases could be attributed to HPV infection. Our results show that, even in this monogamous population, HPV is the major risk factor for high-grade cervical neoplasia.

Inter-observer variation in cytological and histological diagnoses of cervical neoplasia and its epidemiologic implication

Inter-observer variation in cytohistological diagnosis was assessed for 1506 cervical smears and 883 histological slides from four case-control studies on cervical neoplasia. The kappa statistic among a panel of three cytopathologists was highest for diagnosis of invasive cancer (0.70 for cytology and 0.74 for histology), followed by normal/inflammatory in cytology (0.68) and CIN III in histology (0.58). There was also nearly perfect agreement between the final panel diagnoses and the original diagnoses made by local cytopathologists, except for those of CIN III. Inter-observer variation in diagnosis for CIN III was inversely associated with age, number of children (in histology) and sexual activity (in cytology). However, the odds ratios for CIN III calculated by each cytopathologist's diagnosis were not different from each other for any etiologic factor. These results indicate that the diagnoses of invasive cancer and of normal/inflammatory changes are highly reproducible and that the inter-observer variation does not have much impact on the etiologic risk estimates.

Epidemiology of cervical intraepithelial neoplasia: the role of human papillomavirus

The evidence implicating specific HPV types in the aetiology of cervical cancer is now strong enough to establish a causative role. HPV infection of the cervix affects the developing immature metaplastic cells of the transformation zone. Cervical neoplasia can be viewed as the interaction of high risk papillomavirus and immature metaplastic epithelium. Once maturity is reached, there is minimal risk of subsequent development of cervical squamous neoplasia. Exposure to HPV is an extremely common event, especially in young sexually active women. Yet, despite frequent HPV exposure at that phase of life in which the cervical transformation zone is at its most vulnerable, established expressed disease is relatively uncommon. Most studies in which the natural history of CIN is not altered by cervical biopsy reveal a progression rate from low to high grade CIN of less than one third. Where viral type is taken into account, however, the progression rate from normal but high risk HPV-infected cervical epithelium to CIN 2 or 3 is higher. Despite this, most cervical abnormalities will not transform into invasive cancer, even if left untreated. The variance between the high rate of HPV infection, the intermediate rate of CIN and the relatively low rate of cervical cancer establishes a stepwise gradient of disease of increasing severity with decreasing prevalence. In an immunocompetent host, HPV infection alone does not appear to be sufficient to induce the step from high grade CIN to invasion. Epidemiological studies indicating that HPV infection with oncogenic viral types is far more common than cervical neoplasia suggest the necessity of cofactors in cervical carcinogenesis. The long time-lag between initial infection and eventual malignant conversion suggests that random events may be necessary for such conversion, and the spontaneous regression of many primary lesions suggests that most patients are not exposed to these random events. Potential cofactors include cigarette smoking, hormonal effects of oral contraceptives and pregnancy, dietary deficiencies, immunosuppression and chronic inflammation. In those women who develop cervical cancer, malignant progression is rarely rapid, more commonly taking many years or decades. Malignant progression has been documented in patients who presented initially with only low grade HPV-induced atypia. On the other hand, progression may be a misnomer, as 'apparent' progression may really represent adjacent 'de novo' development of higher grade CIN. Although most cervical cancers contain high risk HPV types, up to 15% of such cancers test negative for HPV, raising the possibility that a few, usually more aggressive, cervical cancers may arise from from a non-viral source.(ABSTRACT TRUNCATED AT 400 WORDS)

Widowhood and divorce related to cancer risk in middle-aged women. A nested case-control study among Norwegian women born between 1935 and 1954

We have examined whether the risk of cancer among divorced or widowed Norwegian women born between 1935 and 1954 was any different from that of married women. Among a total of approximately 600,000 women, we applied a nested case-control design. Thus, the study was population-based and included 17,235 incident cases of cancer with 34,460 age-matched controls. For widowed women, there was no overall relation with cancer. For divorced women, 2 strikingly different associations were apparent. A reduced risk was seen for cancers of a number of sites, including thyroid, endometrium, colorectum, and breast, as well as malignant melanoma and hematologic malignancies, with statistically significant estimates of relative risk ranging from 0.64 to 0.84. In contrast, divorced women had a strongly elevated risk of lung and cervical cancer. Moreover, there was a gradual reduction in the relative risk of cancer at some sites with increasing age at divorce, and with duration of marriage prior to divorce. In this study of middle-aged women, the risk of cancer among widows was no different from that of married women. Divorced women had an increased risk of cancers which are related to cigarette smoking but, simultaneously, a reduced risk of cancer at a number of other sites. Since the negative associations for some cancers were strongly related to increasing age at divorce and to duration of marriage, the results may indicate that the reduction in risk is related to factors which characterize the marital period preceding divorce.

The role of HPV in the etiology of cervical cancer

To assess the association between human papillomavirus (HPV) and cervical cancer we have carried out two case-control studies of cervical intraepithelial neoplasia grade III (CIN III) (525 cases and 512 matched controls) and two case-control studies of invasive squamous cell carcinoma (436 cases and 387 population controls) in Cali, Colombia and nine provinces of Spain. HPV DNA detected by polymerase chain reaction, a PCR-based hybridization assay in the exfoliated cells of the uterine cervix, was the strongest risk factor in both countries. For invasive cancer the adjusted odds ratios and 95% confidence intervals were: 46.2 (18.5-115.1) in Spain and 15.6 (6.9-34.7) in Columbia and for CIN III they were: 56.9 (24.8-130.6) in Spain and 15.5 (8.2-29.4) in Columbia. This strong association was specific for types 16, 18, 31, 33 and 35 and also for HPV types not yet characterized. Hormonal factors such as oral contraceptives and high parity appear to confer an additional risk increasing the progression from chronic HPV infection to cancer. Our overall results indicate that HPV is the main cause of cervical cancer in two countries with contrasting rates of cervical cancer, Columbia having an incidence rate about 8 times higher than Spain.

Human papillomavirus and invasive cervical cancer in Brazil

A hospital-based case-control study was undertaken to examine the role of human papillomavirus (HPV) in the development of invasive cervical cancer in Brazil. The study included 199 histologically confirmed incident cases and 225 age-frequency-matched controls selected from a wide range of diagnostic categories. A polymerase chain reaction technique was used to detect HPV DNA in cervical specimens collected with spatula and brush. HPV DNA was detected in 84% of the cases compared with 17% of controls. Grouping HPV types 16, 18, 31 and 33, 66% of the cases were positive compared with only 6% of the controls. In addition to HPV, number of sexual partners, early age at first intercourse, parity and duration of oral contraceptive use were significantly associated with an increased risk of cervical cancer. A history of previous Papanicolaou smears was significantly associated with a decreased risk. After adjustment, only presence of HPV DNA, parity and history of previous smears remained as independent risk factors. The adjusted odds ratios of cervical cancer associated with HPV 16, 18, 31, and 33 was 69.7 (95% confidence interval 28.7-169.6) and with unidentified types was 12.0 (5.1-28.5). The very high risks found in this study further implicate this virus in the aetiology of cervical cancer.

The causal link between human papillomavirus and invasive cervical cancer: a population-based case-control study in Colombia and Spain

To evaluate the association between human papillomavirus (HPV) and cervical cancer, we performed a population-based case-control study in Columbia and Spain, the former country having an incidence rate of cervical cancer about 8 times higher than the latter. It included 436 cases of histologically confirmed invasive cervical cancer and 387 randomly selected population controls. Information on demographic variables, sexual behaviour and other risk factors was obtained by interview. HPV-DNA was measured in cervical-swab specimens with 3 hybridization assays: ViraPap, Southern hybridization (SH) and polymerase chain reaction (PCR). The presence of HPV-DNA and detection of types 16, 18, 31, 33 and 35 were strongly associated with cervical cancer in each country regardless of the assay used. For both countries combined the adjusted odds ratios and 95% confidence intervals were: ViraPap OR = 25.9 (10.0-66.7); SH OR = 6.8 (3.4-13.4); and PCR OR = 28.8 (15.7-52.6). HPV-16 was the most common type detected in both cases and controls. Our results indicate that there is a very strong association between HPV 16, 18, 31, 33 and 35 and invasive cervical cancer and that this association is probably causal.

Risk factors for cervical cancer in Colombia and Spain

A population-based case-control study of cervical cancer was conducted in Spain and Colombia to assess the relationship between cervical cancer and exposure to human papillomavirus (HPV), selected aspects of sexual and reproductive behaviour, use of oral contraceptives, screening practices and smoking. The study included 436 cases of histologically confirmed squamous-cell carcinoma and 387 age-stratified controls randomly selected from the general population that generated the cases. The presence of HPV DNA in cervical scrapes was assessed by PCR-based methods and was the strongest risk factor (OR = 23.8; 13.4-42.0). Risk estimates for any other factor were only slightly modified after adjusting for HPV status. Among women found positive for HPV DNA, only the use of oral contraceptives was a risk factor for cervical cancer (OR = 6.5; 1.3-31.4 for ever vs. never use). Patients with cervical cancer who were HPV DNA-negative retained most of the established epidemiological features of this disease. This suggests that some instances of HPV infection went undetected or that other sexually transmitted factor(s) contribute to the causation of cervical cancer. Early age at first intercourse (OR = 4.3; 2.1-9.0 for age < 16 vs. 24+) and early age at first birth (OR = 5.0; 1.8-14.2 for age < 16 vs. 24+) were associated with increased risk of cervical cancer; these effects were independent of one another. Low educational level was a risk factor (OR = 2.5; 1.6-3.9). Number of sexual partners was in our study a surrogate for HPV infection. Smoking and parity after age 24 were weakly and inconsistently associated with the risk of cervical cancer. Previous screening (OR = 0.7; 0.5-1.0) and ever having undergone a Caesarean section (OR = 0.4; 0.2-0.8) were protective factors.