Prostitution, condom use, and invasive squamous cell cervical cancer in Thailand

Ecological validity of cost-effectiveness models of universal HPV vaccination: A systematic literature review

BACKGROUND

The protective (herd) effect of the selective vaccination of pubertal girls against human papillomavirus (HPV) implies a high probability that one of the two partners involved in intercourse is immunised, hence preventing the other from this sexually transmitted infection. The dynamic transmission models used to inform immunisation policy should include consideration of sexual behaviours and population mixing in order to demonstrate an ecological validity, whereby the scenarios modelled remain faithful to the real-life social and cultural context. The primary aim of this review is to test the ecological validity of the universal HPV vaccination cost-effectiveness modelling available in the published literature.

METHODS

The research protocol related to this systematic review has been registered in the International Prospective Register of Systematic Reviews (PROSPERO: CRD42016034145). Eight published economic evaluations were reviewed.

RESULTS

None of the studies showed due consideration of the complexities of human sexual behaviour and the impact this may have on the transmission of HPV.

DISCUSSION

Our findings indicate that all the included models might be affected by a different degree of ecological bias, which implies an inability to reflect the natural demographic and behavioural trends in their outcomes and, consequently, to accurately inform public healthcare policy. In particular, ecological bias have the effect to over-estimate the preference-based outcomes of selective immunisation. A relatively small (15-20%) over-estimation of quality-adjusted life years (QALYs) gained with selective immunisation programmes could induce a significant error in the estimate of cost-effectiveness of universal immunisation, by inflating its incremental cost effectiveness ratio (ICER) beyond the acceptability threshold. The results modelled here demonstrate the limitations of the cost-effectiveness studies for HPV vaccination, and highlight the concern that public healthcare policy might have been built upon incomplete studies.

HPV vaccination programs have not been shown to be cost-effective in countries with comprehensive Pap screening and surgery

Pap screening combined with loop electrosurgical excision procedures (LEEP) is almost 100% effective in preventing cervical cancer mortality yet many countries with these procedures have now implemented broad HPV vaccination programs. HPV vaccines have not been demonstrated to be more effective or safer than Pap screening in the prevention of cervical cancer and Pap screening will still be required even in vaccinated women. The HPV vaccine costs Au$450 per person and it does not protect against ~30% of cancer. This investigation analyses the cost-effectiveness of using the HPV vaccine in countries where Pap screening and surgical procedures have already reduced cervical cancer mortality to very low rates. Cost-effectiveness of vaccination programs is being determined by mathematical models which are founded on many assumptions. It is necessary to examine the rigor of these assumptions to be certain of the health benefits that are predicted. In 2002 scientists concluded that HPV 16 and 18 were the central and independent cause of most cervical cancer. This conclusion was based on molecular technology. If HPV 16 and 18 infections are the central and independent cause of most cervical cancer then the incidence of HPV 16 and 18 should vary with the incidence and mortality of cervical cancer worldwide. This correlation does not exist. It is also observed that the majority of HPV 16/18 infections do not lead to cervical cancer. This indicates that other etiological or ‘risk’ factors are necessary for persistent HPV infection to progress to cancer. The benefits of HPV vaccines have been determined by using pre-cancerous lesions in young women as a surrogate for cervical cancer. This surrogate is found to be inadequate as an end-point for cervical cancer. Clinical trials have only provided speculative benefits for the efficacy of HPV vaccines against cancer and the long-term risks of the vaccine have not been established. Pap screening will still be required in vaccinated women hence HPV vaccination programs are not cost-effective, and may do more harm than good, in countries where regular Pap screening and surgery has already reduced the burden of this disease.

Perceived risk of cervical cancer in Appalachian women

OBJECTIVE

To examine perceptions of cervical cancer risk in elevated-risk Appalachians.

METHODS

Appalachian women (n=571) completed interviews examining self-regulation model factors relevant to perceived risk of cervical cancer.

RESULTS

Women with good/very good knowledge of cervical cancer, greater worry, and history of sexually transmitted infection had higher odds of rating their perceived risk as somewhat/much higher than did other women. Former smokers, compared to never smokers, had lower risk perceptions.

CONCLUSIONS

Self-regulation model factors are important to understanding perceptions of cervical cancer risk in underserved women. The relationship of smoking and worry to perceived risk may be a target for intervention.

Male circumcision and genital human papillomavirus: a systematic review and meta-analysis

BACKGROUND

Human papillomavirus (HPV) infection is the principal cause of invasive cervical cancer. There is some evidence that male circumcision (MC) may protect against HPV infection and related disease in both men and women. The purpose of this study was to conduct a systematic review of the literature to assess the association between MC and genital HPV infection indicators including genital warts.

METHODS

A systematic search of Medline was conducted to identify all relevant studies from February 1971 to August 2010. Effect estimates were included in random effects models.

RESULTS

A total of 21 studies with 8046 circumcised and 6336 uncircumcised men were included in the meta-analysis. MC was associated with a statistically significant reduced odds of genital HPV prevalence (odds ratio = 0.57, 95% confidence interval: 0.42-0.77). This association was also observed for genital high-risk HPV prevalence in 2 randomized controlled trials (odds ratio = 0.67, 95% confidence interval: 0.54-0.82). No associations were found between MC and genital HPV acquisition of new infections, genital HPV clearance, or genital warts.

CONCLUSIONS

This meta-analysis shows a robust inverse association between MC and genital HPV prevalence in men. However, more studies are needed to adequately assess the effect of MC on the acquisition and clearance of HPV infections. MC could be considered as an additional one-time preventative intervention likely to reduce the burden of HPV-related diseases both in men and women, particularly among those countries in which HPV vaccination programs and cervical screening are not available.

Race and prevalence of human papillomavirus infection among men residing in Brazil, Mexico and the United States

Human papillomavirus (HPV) causes anal, penile and oropharyngeal cancers in men. Genital HPV prevalence in men appears to vary by world region with men residing in Asia having among the lowest prevalence. Unfortunately, there is little information on prevalence of HPV infection in men by race. The purpose of this study was to examine HPV prevalence by race across three countries. 3,909 men ages 18-70 years enrolled in an ongoing prospective cohort study of the natural history of HPV in men (The HIM Study) were included in the analysis. Participants completed risk factor questionnaires and samples were taken from the penile epithelium and scrotum for HPV detection. HPV testing of the combined DNA extract was conducted using PCR and genotyping. Asian/Pacific Islanders had the lowest HPV prevalence of 42.2% compared to Blacks (66.2%), and Whites (71.5%). The Asian/Pacific Islander race was strongly protective in univariate analysis (prevalence ratio (PR) = 0.59; 95% confidence interval (CI): 0.48-0.74) and multivariate analysis for any HPV infection (PR = 0.65; 95% CI: 0.52-0.8). Stratified analysis by lifetime number of female partners also showed strong inverse associations with the Asian/Pacific Islander race. We consistently observed the lowest prevalence of HPV infection among Asian/Pacific Islanders with moderate inverse associations even after various adjustments for potential confounding factors. Unmeasured behavioral factors, sexual mixing with low risk women, and/or race-specific differences in the frequency of germline variations among immune regulating genes may underlie these associations. Further studies among Asian populations that incorporate measures of immuno-genetics are needed to understand this phenomenon.

Prevention strategies against human papillomavirus in males

Sexually transmitted human papillomavirus (HPV) infection is very common in men and women. Oncogenic HPV is strongly associated with cancers and high-grade dysplasias of the anogenital tract, including the anus, penis, and also a proportion of oropharyngeal cancers. In reducing male disease burden, some consider screening and treatment for high-grade anal dysplasia (AIN) to prevent anal cancer in high-risk populations. Such strategies have wide implications for the workforce, and require more evidence for the optimal management of AIN. Male sexual behavior, with consequent HPV infection and disease contribute to considerable disease burden in females. Hence, inclusion of males in prophylactic HPV vaccination programs should prevent HPV-related disease in males as well as substantially reducing disease burden in females. Clinical trial data in males 16-26 years for the quadrivalent vaccine show it is well tolerated, induces a strong type-specific immunological response comparable to that of females, and reduced vaccine HPV-type-related genital infection, as well as disease. Cost-benefit analyses and mathematical modeling show that the most cost-effective strategy involves routine administration of this vaccine to 12-year-old females, with catch-up vaccination of 12- to 24-year-olds, with the most effective strategy in disease reduction including men and/or boys in the program. Such a vaccination strategy including 12-year-old boys is projected by 2050 to reduce HPV 16 infection by 88-94% in females and 68-82% in males, plus the aforementioned male HPV- related cancers by 22-27%. Therefore, inclusion of males in an HPV vaccination program is likely to have significant health and economic benefits over and above those observed from current female-only programs. However, comprehensive cost-benefit analyses are needed to determine the efficacy of these programs in the overall population. Such analyses will be crucial for the design, acceptance, and implementation of these vaccination programs into clinical practice globally.

Human papillomavirus infection in men residing in Brazil, Mexico, and the USA

OBJECTIVE

To assess Human Papillomavirus (HPV) type distribution among men ages 18 years and older recruited from three different countries utilizing a common protocol for sampling HPV detection, and to evaluate whether HPV detection differs by age and country. MATERIAL AD METHODS: The study protocol includes a pre-enrollment run-in visit, a baseline (enrollment) visit, and nine additional visits after enrollment scheduled six months apart. For this analysis, the first 1160 men who completed both the run-in and baseline visit were included. To maximize sampling and prevent fraying of applicators, three different applicators were utilized to sample the external genitalia of participants among different anatomic sites. These samples were later combined to form a single sample for the detection of HPV using polymerase chain reaction (PCR) for amplification of a fragment of the HPV L1 gene.

RESULTS

Among 1160 men from Brazil, Mexico, and the United States (U.S.), overall HPV prevalence was 65.2%; with 12.0% oncogenic types only, 20.7% non-oncogenic types only, 17.8% both oncogenic and non-oncogenic, and 14.7% unclassified infections. Multiple HPV types were detected in 25.7% of study participants. HPV prevalence was higher in Brazil (72.3%) than in the U.S. (61.3%) and Mexico (61.9%). HPV 16 (6.5%), 51 (6.5%), and 59 (5.3%) were the most commonly detected oncogenic infections, and HPV 84 (7.7%), 62 (7.3%), and 6 (6.6%) were the most commonly detected non-oncogenic infections. Overall HPV prevalence was not associated with age. However, significant associations with age were observed when specific categories of oncogenic, non-oncogenic, and unclassified HPV infections were considered.

CONCLUSIONS

Studies of HPV type distribution among a broad age range of men from multiple countries is needed to fill the information gap internationally with respect to our knowledge of HPV infection in men.

The human papillomavirus infection in men study: human papillomavirus prevalence and type distribution among men residing in Brazil, Mexico, and the United States

Male sexual behavior influences the rates of cervical dysplasia and invasive cervical cancer, as well as male human papillomavirus (HPV) infection and disease. Unfortunately, little is known regarding male HPV type distribution by age and across countries. In samples combined from the coronal sulcus, glans penis, shaft, and scrotum of 1,160 men from Brazil, Mexico, and the United States, overall HPV prevalence was 65.2%, with 12.0% oncogenic types only, 20.7% nononcogenic types only, 17.8% both oncogenic and nononcogenic, and 14.7% unclassified infections. Multiple HPV types were detected in 25.7% of study participants. HPV prevalence was higher in Brazil (72.3%) than in the United States (61.3%) and Mexico (61.9%). HPV16 (6.5%), HPV51 (5.3%), and HPV59 (5.3%) were the most commonly detected oncogenic infections, and HPV84 (7.7%), HPV62 (7.3%), and HPV6 (6.6%) were the most commonly detected nononcogenic infections. Overall HPV prevalence was not associated with age. However, significant associations with age were observed when specific categories of HPV, nononcogenic, and unclassified HPV infections were considered. Studies of HPV type distribution among a broad age range of men from multiple countries is needed to fill the information gap internationally with respect to our knowledge of HPV infection in men.

Age-specific prevalence, incidence, and duration of human papillomavirus infections in a cohort of 290 US men

BACKGROUND

Human papillomavirus (HPV) infections cause disease in men and women, and male-to-female HPV transmission influences the risk of cancer in females. The purpose of the present study was to describe the overall and age-specific incidence and clearance of HPV infections in men.

METHODS

In a prospective cohort study of 290 men aged 18-44 years, participants were examined at baseline and every 6 months, with a mean duration of follow-up of 15.5 months.

RESULTS

The period prevalence was 52.8% for any, 31.7% for oncogenic, and 30.0% for nononcogenic HPV infection. The 12-month cumulative risk of acquiring a new HPV infection was 29.2%. Incidences of HPV types 6, 11, 16, and 18 were 2.8, 0.5, 4.8, and 0.8 per 1000 person-months, respectively. The median time to clearance of any HPV infection was 5.9 months (95% confidence interval, 5.7-6.1 months), with comparable times to clearance for oncogenic and nononcogenic infections. Approximately 75% of men tested negative for any HPV 12 months after initial HPV detection. Age was not significantly associated with HPV incidence or duration of infection in men.

CONCLUSION

HPV infection in men was common, with relatively rapid rates of acquisition and clearance.

The optimal anatomic sites for sampling heterosexual men for human papillomavirus (HPV) detection: the HPV detection in men study

Background. Human papillomavirus (HPV) infection in men contributes to infection and cervical disease in women as well as to disease in men. This study aimed to determine the optimal anatomic site(s) for HPV detection in heterosexual men.Methods. A cross-sectional study of HPV infection was conducted in 463 men from 2003 to 2006. Urethral, glans penis/coronal sulcus, penile shaft/prepuce, scrotal, perianal, anal canal, semen, and urine samples were obtained. Samples were analyzed for sample adequacy and HPV DNA by polymerase chain reaction and genotyping. To determine the optimal sites for estimating HPV prevalence, site-specific prevalences were calculated and compared with the overall prevalence. Sites and combinations of sites were excluded until a recalculated prevalence was reduced by <5% from the overall prevalence.Results. The overall prevalence of HPV was 65.4%. HPV detection was highest at the penile shaft (49.9% for the full cohort and 47.9% for the subcohort of men with complete sampling), followed by the glans penis/coronal sulcus (35.8% and 32.8%) and scrotum (34.2% and 32.8%). Detection was lowest in urethra (10.1% and 10.2%) and semen (5.3% and 4.8%) samples. Exclusion of urethra, semen, and either perianal, scrotal, or anal samples resulted in a <5% reduction in prevalence.Conclusions. At a minimum, the penile shaft and the glans penis/coronal sulcus should be sampled in heterosexual men. A scrotal, perianal, or anal sample should also be included for optimal HPV detection.

Condom use and the risk of genital human papillomavirus infection in young women

BACKGROUND

To evaluate whether the use of male condoms reduces the risk of male-to-female transmission of human papillomavirus (HPV) infection, longitudinal studies explicitly designed to evaluate the temporal relationship between condom use and HPV infection are needed.

METHODS

We followed 82 female university students who reported their first intercourse with a male partner either during the study period or within two weeks before enrollment. Cervical and vulvovaginal samples for HPV DNA testing and Papanicolaou testing were collected at gynecologic examinations every four months. Every two weeks, women used electronic diaries to record information about their daily sexual behavior. Cox proportional-hazards models were used to evaluate risk factors for HPV infection.

RESULTS

The incidence of genital HPV infection was 37.8 per 100 patient-years at risk among women whose partners used condoms for all instances of intercourse during the eight months before testing, as compared with 89.3 per 100 patient-years at risk in women whose partners used condoms less than 5 percent of the time (adjusted hazard ratio, 0.3; 95 percent confidence interval, 0.1 to 0.6, adjusted for the number of new partners and the number of previous partners of the male partner). Similar associations were observed when the analysis was restricted to high-risk and low-risk types of HPV and HPV types 6, 11, 16, and 18. In women reporting 100 percent condom use by their partners, no cervical squamous intraepithelial lesions were detected in 32 patient-years at risk, whereas 14 incident lesions were detected during 97 patient-years at risk among women whose partners did not use condoms or used them less consistently.

CONCLUSIONS

Among newly sexually active women, consistent condom use by their partners appears to reduce the risk of cervical and vulvovaginal HPV infection.

Synergy between sexual abuse and cervical cancer in causing sexual dysfunction

Experiencing a sexual abuse creates a life-long traumatic memory. The life-long effect of such abuse on sexuality, well-being, the risk of contracting cervical cancer, or problems after treatment for cervical cancer is not known. A population-based follow-up study in 1996-97 that used an anonymous postal questionnaire for data collection, 256 women with stage IB-IIA cervical cancer registered in 1991-92 in Sweden, and 350 women without cervical cancer frequency matched for age and region of residence, provided information. Among the women with a history of cervical cancer and the control women, 46 (18%) and 50 (15%), respectively, reported a history of sexual abuse. The follow-up was 1-70 years after the sexual abuse. The relative risk (with 95% confidence interval) of decreased well-being was 2.4 (1.1-5.2) among controls and 2.7 (1.1-6.4) among former cervical cancer patients. A history of both sexual abuse and cervical cancer gave a relative risk of 30.0 (7.0-129.0) for superficial dyspareunia. Sexual abuse increased the risk of sexual problems after treatment. The sexually abused cervical cancer patients were generally less willing than other patients to trade off possible maximal survival and forgo parts of the treatment. A history of sexual abuse and cervical cancer are both independent risk factors for sexual dysfunction and decreased well-being, and there may be a large synergy when both factors are combined. Diagnosis and treatment of cervical cancer may be improved by recognition of a sexual abuse history.

Condom use and other factors affecting penile human papillomavirus detection in men attending a sexually transmitted disease clinic

BACKGROUND AND OBJECTIVES

Human papillomavirus (HPV) is the primary cause of cervical, anal, and other anogenital cancers, but risk factors for penile HPV detection in men have not been well-characterized.

GOAL

The goal of this study was to identify correlates of penile HPV detection in ethnically diverse men attending a sexually transmitted disease clinic.

STUDY

A cross-sectional investigation was conducted among 393 men. Participants completed a risk-factor questionnaire and underwent testing for penile HPV DNA. Presence of HPV DNA was assessed using polymerase chain reaction with PGMY primers and reverse line blot genotyping. Logistic regression analyses were conducted to identify variables associated with any-type, oncogenic, and nononcogenic HPV.

RESULTS

Circumcision was associated with reduced risk for oncogenic, nononcogenic, and overall HPV. Regular condom use was associated with reduced risk for oncogenic and overall HPV.

CONCLUSION

These findings, if confirmed by other studies, could impact public health practices and messages regarding HPV.

Contribution of epigenetic risk factors but not p53 codon 72 polymorphism to the development of cervical cancer in Northeastern Thailand

Relationships between cervical cancer and risk factors were investigated in Northeastern Thailand. Cases (n = 90) with squamous cell cervical cancer (SCCA) and age matched healthy controls (n = 100) were recruited. The p53 codon 72 polymorphism, proline and arginine allele, was studied by the polymerase chain reaction-restriction fragment length polymorphism. There was no significant difference in the allele and the genotype distribution between the SCCA and the control groups (P > 0.05). Significant difference was observed in the number of sexual partners (P < 0.003) age at the first sexual intercourse (P < 0.03) and number of parities ( P< 0.006). After adjusted by age and p53 genotype, significant difference was still observed in the number of sexual partners (P = 0.017) The partners' smoking increased the risk to develop SCCA. Increased odds ratios were observed when the partner had smoking history both at present (3.31; P < 0.003) and in the past (3.36; P < 0.003). The p53 polymorphism itself may not be a risk factor for cervical cancer in Northeastern Thailand. Much attention should be paid to the presence of other risk factors such as sexual behaviors and smoking habits in the prevention of cervical cancer in this region.

Behavioural risk factors for cervical cancer from a prospective study in Khon Kaen, Northeast Thailand

Fifty seven cases of cancer of the cervix were identified within a cohort of 16,648 women enrolled in a cohort study of lifestyle and cancer in a rural population of Northeast Thailand. They were compared with 228 matched controls from the same cohort, with respect to demographic, behavioural and reproductive factors potentially associated with risk of the disease. Number of pregnancies and age at having first child were associated with the risk of cervical cancer, but in contrast to studies elsewhere, age at having first sexual intercourse, number of sexual partners and sexually-transmitted infections were not associated with risk. The lack of effect may be simply due to the small size of the study. But it is also likely that these aspects of female sexual behaviour are not very relevant in a relatively conservative rural population. These aspects may be investigated further in future, as new incident cancers are accrued into the cohort.

Family physicians' knowledge of risk factors for cervical cancer

BACKGROUND

A woman's risk for cervical cancer has been used by physicians to guide the initiation and frequency of a Pap smear. The aim of this study was to determine family physicians' knowledge of risk factors for cervical cancer and perceived importance of risk in screening women.

METHODS

The self-administered questionnaire was mailed to 5000 randomly selected active members of the American Academy of Family Physicians (AAFP).

RESULTS

Data from 2748 usable questionnaires indicated the mean number of risks considered for cervical cancer was 4.5. Physician's age and the number of reported risks were inversely correlated (p = 0.0001). Female physicians reported significantly more risk factors than male physicians (p = 0.05). The number of Pap smears performed per month was positively correlated with the number of risk factors reported (p = 0.001). Only 10% of the physicians indicated that they perform a Pap smear at the same interval regardless of the risk of the woman.

CONCLUSIONS

This sample of family physicians has a limited understanding of the risk factors for cervical cancer. This was true regardless of the age, gender, training, race, geographic location, or practice setting of the responding physician. Yet the usual practice of screening for cervical cancer reported by these physicians would suggest that knowledge and use of risk factors would be a critical aspect of screening for cervical cancer.

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.

Do condoms prevent genital HPV infection, external genital warts, or cervical neoplasia? A meta-analysis

BACKGROUND

Although condoms most likely prevent HIV infection, evidence of their effectiveness against other sexually transmitted diseases is mixed.

GOAL

The goal of the study was to determine whether condom use prevents genital human papillomavirus (HPV) infection and HPV-related conditions.

STUDY DESIGN

We conducted a literature review and meta-analysis of the effect of condom use on the prevention of genital warts, subclinical HPV infection, cervical intraepithelial neoplasia (CIN), and invasive cervical cancer (ICC).

RESULTS

Among 27 estimates from 20 studies, there was no consistent evidence that condom use reduces the risk of becoming HPV DNA-positive. However, risk for genital warts, CIN of grade II or III (CIN II or III), and ICC was somewhat reduced.

CONCLUSIONS

Available data are too inconsistent to provide precise estimates. However, they suggest that while condoms may not prevent HPV infection, they may protect against genital warts, CIN II or III, and ICC.

Determinants of cervical cancer rates in developing countries

Although cervical cancer (CC) is a leading cause of cancer-related deaths in developing countries, incidence rates vary considerably, ranging from 3 to 61 per 10(5) females. Identifying determinants of high vs. low rates may suggest population-level prevention strategies. CC rates for 175 countries were obtained from the IARC. Country-specific behavioral, health, economic and demographic measures were obtained from United Nations agencies and other international organizations. Regression analyses performed for 127 low or medium developed countries identified both geography and religion as independently associated with high CC rates. Among behavioral measures, high fertility rates, early age at birth of first child and high teenage birth rates were significantly associated with high CC rates. Countries with high CC rates had fewer doctors per capita, less immunization coverage, more HIV infections and shorter life expectancies. CC rates also tended to be higher in countries with more spending on health and younger, less educated populations. Patterns of CC rates suggest that programmatic approaches, such as promoting delayed childbearing and sexual monogamy, may be appropriate interventions. For countries with high CC rates and some flexibility in their health-care budgets, a once-in-a-lifetime screen of women 30-50 years of age, using Pap smears, direct visual inspection and/or HPV DNA testing, may be cost-effective. Finally, relatively low immunization rates and a shortage of health-care workers in countries with high CC rates suggest potential challenges for introducing prophylactic HPV vaccines.

Cancer control in Thailand

Cancer in Thailand is becoming a significant health problem. It is the leading cause of death in Thailand. Several cancers can be prevented by a nationwide campaign of health education to prevent raw fish intake and an antismoking campaign. An appropriate cervical cancer and breast cancer screening program can improve the recent prevalence of both and lead to better results of treatment. Research related to the carcinogenesis mechanism of certain cancers can lead to greater understanding and a better plan of control.

The relationship of human papillomavirus (HPV) detection to pap smear classification of cervical-scraped cells in asymptomatic women in northeast Thailand

OBJECTIVE

To correlate the detection of human papillomavirus (HPV) with the Pap smear classification of cervical-scraped cells from asymptomatic women living in northeast Thailand.

METHODS

A total of 260 asymptomatic women attending the Obstetrics and Gynecology's Outpatient Clinic, Srinagarind Hospital, Thailand, were interviewed for risk factors and cervical scrapes were taken. The cells were examined by Pap smear for cytological changes and by PCR for HPV DNAs--nononcogenic (HPVs 6 and 11) and oncogenic (HPVs 16, 18 and 33) types. Cervical biopsies were taken from women with abnormal Pap smears for histological examination.

RESULTS

Of the 260 cervical smear samples, the cervical cells were classified as normal and abnormal in 174 and 86, respectively. Twenty-three percent of all samples were positive for overall HPV DNA. HPV DNAs (mostly HPVs 6 and 11) were detected in 21% of normal cells, and the higher detection rate (27%) for HPV DNA in abnormal cells gradually increased in severity from 16% in Class 3 to 35 and 60% in Classes 4 and 5, respectively. Histologically 46, 90 and 100% of HPV detection was associated with CIS, SCC and adenocarcinoma, respectively. Almost all of the HPV DNAs detected were types 16, 18 or 33. There was no significant association between HPV infection and reproduction history, sexual behavior and demographic variables.

CONCLUSION

We speculated that an abnormal Pap smear and the detection of an oncogenic type HPV may indicate the presence of neoplastic cells in asymptomatic woman who might be at risk for the development of cervical cancer.

'With the best of reasons': cervical cancer prevention policy and the suppression of sexual risk factor information

Cervical cancer is a very common but largely preventable cancer. Despite considerable medical knowledge of risk and even causal factors, possible social-behavioural strategies for the primary prevention of cervical cancer have rarely been explored as a viable addition to cervical screening. We examine key policy documents and interview 18 key informants on cervical cancer prevention in New Zealand. Using a discourse analytic approach we identify and discuss two discourses (which we have labelled 'protectionism' and 'right to know') which inform positions on whether or not women should be provided with information regarding sexual risk factors for cervical cancer. Cervical cancer prevention policy in New Zealand, which largely reflects a protectionist discourse, suppresses sexual risk factor information and focuses exclusively on cervical screening. The right to know discourse informs an alternative position, which contends that women have a right to be informed about risk factors. We discuss these positions in relation to questions about women's rights, the principle of informed choice, and attempts to judge what is in women's 'best interests.'

Risk factors for cervical cancer in Thailand: a case-control study

BACKGROUND

Human papillomaviruses (HPV) types 16 and 18 are clearly involved in the etiology of cervical cancer, but the evidence for the carcinogenicity of other HPV types is limited. Cofactors involved in the progression from infection with HPV to high-grade precursors and cancer have not been clearly defined by the results of previous studies.

METHODS

We conducted a hospital-based, case-control study of invasive cervical cancer to investigate risk in relation to HPV infection and its epidemiologic cofactors in Hat-Yai, Thailand. A total of 338 patients with squamous cell carcinoma, 39 patients with adenocarcinoma/adenosquamous carcinoma, and 261 control subjects were included in the study and were interviewed to obtain information with regard to cervical cancer risk factors. HPV DNA presence in cervical exfoliated cells or frozen biopsy specimens was determined by a polymerase chain reaction assay.

RESULTS

HPV DNA was detected in 95% of patients with squamous cell carcinoma, 90% of those with adenocarcinoma/adenosquamous carcinoma, and 16% of control subjects. For patients with squamous cell carcinoma, the most common types of HPV found were type 16 (60% of the positives), type 18 (18%), type 58 (3%), type 52 (3%), and type 31 (2%). For patients with adenocarcinoma/adenosquamous carcinoma, the most common HPV types found were type 18 (60% of the positives), type 16 (37%), and type 45 (3%). The risk factors that remained associated with risk of both histologic types after adjustment for HPV and their mutual confounding effects were limited education, increasing number of sexual partners, history of venereal diseases, and interval since last Pap smear (i.e., cytologic) test. Among patients with squamous cell carcinoma, some association with smoking was also observed.

CONCLUSION

New preventive strategies for cervical cancer will require the consideration of multiple HPV types.