Policy analysis of cervical cancer screening strategies in low-resource settings: clinical benefits and cost-effectiveness

Performance of direct visual inspection of the cervix with acetic acid and magnification in a previously screened population

OBJECTIVE

To assess the screening performance of direct visual inspection with acetic acid and x2 magnification (VIAM) in a previously screened population, as performed by experienced gynecologic nurses with minimal training in VIAM.

PATIENTS AND METHODS

Performance of VIAM was evaluated in 2,080 women from a population-based cohort in Guanacaste, Costa Rica, 5 years after they had negative enrollment results of conventional and liquid-based cytologic analysis, cervigram, and human papillomavirus DNA by Hybrid Capture Tube Test (Digene Corporation, Gaithersburg, MD). The VIAM results were compared with repeat conventional Pap smears, liquid-based cytologic examinations, and cervicography, with adjudication of differences by reference to MY09/MY11 L1 consensus primer polymerase chain reaction detection of oncogenic human papillomavirus DNA.

RESULTS

Less than 5% of women were classified as having positive results using VIAM. The VIAM positivity was also very low among women with high-grade squamous intraepithelial lesion conventional Pap smear results (8.3%), high-grade squamous intraepithelial lesion liquid-based cytologic results (6.3%), or cervigrams suggesting cervical intraepithelial neoplasia 2,3 or cancer (30%). The VIAM positivity was not associated with human papillomavirus DNA positivity.

CONCLUSIONS

As we practiced it, VIAM was not sensitive for detection of possibly serious incident cervical lesions in this previously screened population where cytologic screening is in place.

A cost-effectiveness analysis of screening strategies for cervical intraepithelial neoplasia

OBJECTIVE

To assess the costs and usefulness of colposcopy using three screening strategies for cervical intraepithelial neoplasia (CIN).

MATERIALS AND METHODS

A decision model compared three screening strategies for CIN: (1) patients were screened annually with a conventional Pap smear, (2) patients were screened annually with a liquid-based cytologic method and reflex human papillomavirus testing for atypical squamous cells of undetermined significance results, and (3) patients were screened biennially with a liquid-based cytologic method and reflex human papillomavirus testing for atypical squamous cells of undetermined significance results.

RESULTS

Biennial liquid-based screening was the least expensive strategy with a cost of $9.5 million per 100,000 patients. Annual liquid-based screening was the most expensive strategy at $13.7 million. Annual conventional screening had an intermediate cost of $11.6 million. Biennial liquid-based screening referred the fewest patients to colposcopy (11.8%), followed by annual conventional screening and annual liquid-based screening (15.2% and 15.6%, respectively).

CONCLUSIONS

Each of these treatment strategies is reasonable; however, biennial liquid-based screening would reduce medical costs significantly.

Visual inspection with acetic acid and cytology as screening methods for cervical lesions in Cameroon

OBJECTIVES

To assess the accuracy of visual inspection with acetic acid (VIA) as a screening method for cervical lesions.

METHODS

VIA and cytological smears were carried out on the cervices of non-pregnant women aged 30-60 years with no previous history of cervical cancer. Cervices with aceto white lesions or positive Pap smears, and one in ten negative cervices (control), were biopsied.

RESULTS

5010 women were enrolled, 4813 (96.1%) were screened. 4767 (99.%) had adequate cytology smears. 574 (11.9%) had colposcopy. 1743 biopsies were obtained of which 528 were controls. The sensitivity of VIA was 70.4% versus 47.7% for Pap smear. VIA specificity was 77.6% versus 94.2% for Pap smear; PPV for VIA was 44.0% versus 67.2% for Pap smear; and NPV for VIA was 91.3% versus 87.8% for Pap smear.

CONCLUSIONS

VIA has acceptable test qualities and may in low resource settings be implemented as a large scale screening method.

Cost-effectiveness of whole-body CT screening

PURPOSE

To make preliminary estimates of the effectiveness (in life-years) and cost-effectiveness (in costs per life-year) of whole-body computed tomographic (CT) screening.

MATERIALS AND METHODS

Costs and effectiveness (in life-years) of onetime whole-body CT screening relative to those of no screening were calculated by using a decision-analytic model. It was assumed that any benefits from screening were due to earlier detection of disease and improvement in survival relative to survival with routine care. Eight conditions were included in the model: ovarian, pancreatic, lung, liver, kidney, and colon cancer; abdominal aortic aneurysm; and coronary artery disease. Costs of the screening examination, follow-up tests, and patient care were estimated. The base-case analysis was performed for a hypothetical cohort of 500 000 self-referred asymptomatic 50-year-old men. For sensitivity analyses, the age and sex of the cohort were varied. Results were expressed in 2001 U.S. dollars per life-year gained.

RESULTS

Compared with routine care, whole-body CT screening provided minimal gains in life expectancy (0.016 6 years or 6 days) at an average additional cost of 2513 dollars per patient, or an incremental cost-effectiveness ratio of 151 000 dollars per life-year gained. Most patients (90.8%) had at least one positive finding, but only 2.0% had disease; work-up in patients with a false-positive result of screening accounted for 32.3% of total costs (1720 dollars of 5332 dollars). Results were sensitive to the prevalence of disease, the effect of screening on stage of disease at diagnosis, the specificity of screening, and the costs of follow-up for false-positive findings.

CONCLUSION

Even with assumptions favorable to whole-body CT, implementation of onetime screening would not be cost-effective compared with currently funded medical interventions; follow-up for false-positive findings would add a substantial financial burden to the health care system.

The laboratory diagnosis of genital human papillomavirus infections

Human papillomaviruses (HPVs) are the etiological agents of several genital cancers, including cancer of the uterine cervix. The detection of HPV infection in genital samples may increase the sensitivity of primary and secondary screenings of cervical cancer. HPV testing may also improve the specificity of screening programs, resulting in the avoidance of overtreatment and cost savings for confirmatory procedures. The major determinants of clinical progression of HPV infection include persistence of HPV infection, involvement of high-risk HPV types, high HPV viral load, integration of viral DNA and presence of several potential cofactors. Signal amplification HPV-DNA detection techniques (Hybrid Capture II, Digene Corporation, USA) are standardized, commercially available, and capable of detecting several high-risk HPV types. They also increase the sensitivity of screening for high-grade lesions in combination with cytology. The sensitivity of these techniques to detect high-grade lesions is higher than that of cytology, but the referral rate for colposcopy is greater. These techniques are approved for the triage to colposcopy of women with cervical smears interpreted as atypical squamous cells of undetermined significance. Triage and screening for cervical cancer using HPV will probably be restricted to women aged 30 years or older because of the high prevalence of infection in younger women. Amplification techniques are ideal for epidemiological studies because they minimize the misclassification of HPV infection status. These techniques can detect low HPV burden infections. Consensus primers amplify most genital types in one reaction, and the reverse hybridization of amplicons with type-specific probes allows for the typing of HPV-positive samples. Consensus PCR assays are currently under evaluation for diagnostic purposes. HPV testing is currently implemented for the clinical management of women.

Comparison of pap smear, visual inspection with acetic acid, human papillomavirus DNA-PCR testing and cervicography

OBJECTIVE

To assess the test qualities of four screening methods to detect cervical intra-epithelial neoplasia in an urban African setting.

METHOD

Six hundred fifty-three women, attending a family planning clinic in Nairobi (Kenya), underwent four concurrent screening methods: pap smear, visual inspection with acetic acid (VIA), PCR for high risk human papillomavirus (HR HPV) and cervicography. The presence of cervical intra-epithelial neoplasia (CIN) was verified by colposcopy or biopsy.

RESULT

Sensitivity (for CIN2 or higher) and specificity (to exclude any CIN or cancer) were 83.3% (95% CI [73.6, 93.0]) and 94.6% (95% CI [92.6, 96.5]), respectively, for pap smear; 73.3% (95% CI [61.8, 84.9]) and 80.0% (95% CI [76.6, 83.4]) for VIA; 94.4% (95% CI [84.6, 98.8]) and 73.9% (95% CI [69.7, 78.2]) for HR HPV; and 72.3% (95% CI [59.1, 85.6]) and 93.2% (95% CI [90.8, 95.7]) for cervicography.

CONCLUSION

The pap smear had the highest specificity (94.6%) and HPV testing the highest sensitivity (94.4%). The visual methods, VIA and cervicography, were similar and showed an accuracy in between the former two tests.

Citologia oncológica, captura de híbridos II e inspeção visual no rastreamento de lesões cervicais

Avaliar as alterações na citologia oncológica, na captura híbrida II e na inspeção visual com ácido acético (IVA) a 5% em 684 mulheres atendidas em uma unidade de saúde, e avaliar o desempenho e a concordância entre os exames. Procurar descrever as características sócio-demográficas e reprodutivas (SDR) destas mulheres e sua associação com a presença de doença. As mulheres foram submetidas à coleta de citologia, captura e IVA, e as com exame positivo foram submetidas à colposcopia com biopsia, se necessário. Foi calculado o desempenho dos testes e a associação dos fatores SDR com o diagnóstico histológico foi avaliada por intermédio do cálculo do odds ratio. Embora 198 mulheres apresentassem pelo menos um teste alterado, apenas 21 apresentaram lesão histológica. A sensibilidade dos testes foi semelhante enquanto as especificidades da IVA e da citologia foram maiores que a da captura híbrida II. Apenas a ausência de citologia esteve associada à presença de doença. O desempenho da citologia foi maior que o da IVA, que foi maior que o da captura. A ausência de citologia foi associada com doença histológica.

Molecular basis for advances in cervical screening

Human papillomaviruses (HPVs) cause cervical lesions, which can, in some instances, progress to high-grade neoplasia and cancer. Around half a million cases of cervical cancer occur each year, with most occurring in developing countries where cervical cancer is a major cause of cancer-related death. The reduction in cervical cancer incidence in developed countries is largely attributed to the introduction of cervical screening. Cervical screening currently depends on the identification by cytology of abnormalities in cells taken from the surface of the cervix. The standard Pap test was developed >50 years ago, and despite modifications, still forms the basis of the test currently in use in most routine screening laboratories. Advances in our understanding of the molecular mechanisms that lead to the development of cervical cancer have been slow to impact on screening, despite the relatively high false-negative rates that can be associated with the conventional Pap smear. Improvements in screening strategies fall into a number of categories. Methods that improve cell presentation and attempt to eliminate artefacts/obscuring debris can be combined with image analysis systems in order to enhance diagnostic accuracy. Such approaches still rely on cytological evaluation and do not incorporate advances in our knowledge of how HPV causes cancer. By contrast, markers of virus infection or cell cycle entry, particularly those that offer some degree of prognostic significance, may be able to highlight abnormal cells more reliably than cytology, and could be combined with cytology to improve the detection rate. Our understanding of the molecular biology of HPV infection and the organization of the HPV life-cycle during cancer progression provides a rational basis for marker selection. The general assumption that persistent active infection by high-risk HPV types is the true precursor of cervical cancer provides the rationale for HPV DNA testing in conjunction with enhanced cytology, while the development of RNA-based approaches should allow active infections to be distinguished from those that are latent. The detection in superficial cells of marker combinations at the level of RNA or protein has the potential to predict disease status more precisely than the detection of markers in isolation. There is also a need for better prognostic markers if the predictive value of screening is to be improved. The potential to control infection by vaccination should reduce the incidence of HPV-associated neoplasia in the population, and this may cause a change in the way that screening is carried out. Nevertheless, the lack of a therapeutic vaccine, and the difficulties associated with eliminating infection by multiple high-risk HPV types, means that some form of screening will still be required as a preventive measure for the control of cervical cancer for the foreseeable future.

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

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

Crossing the quality chasm: a requirement for successful cervical cancer prevention in developing countries

Disease prevention requires sociopolitical change, which in turn requires the participation of those for whom the change is intended, including demographic groups at high risk for disease, appropriate governmental authorities, and essential health care personnel. Multiparous women of lowest socioeconomic status, the demographic group at highest risk for the development of cervical cancer, lack sociopolitical leverage almost by definition. Pap screening in developing countries is an idea whose time has come, but it is also an ethical imperative currently lacking a substantial sociopolitical constituency. Noncytologic screening methods currently benefit from sponsorship by corporate manufacturers and by donor organizations such as the Bill and Melinda Gates Foundation. Pap screening efforts in developing countries will benefit from the involvement of cytology organizations based in developed countries. Future assessments of the progress of cervical cancer prevention efforts in developing countries will benefit from additional examination of the interactions between quality and sociopolitical obstacles to change. Many of these obstacles will be elucidated by following the money, as well as the science, involved in cervical screening activities.

Evaluation of Breast Cancer Risk Assessment Techniques: A Cost-effectiveness Analysis

Objective: Assess the effectiveness and cost-effectiveness of using biomarkers and risk assessment tools to stratify women for breast cancer preventive interventions.

Methods: A Markov model was developed to compare risk management strategies for high-risk women considering chemoprevention. Annual screening is compared to the use of chemoprevention for all women and the use of risk assessment technologies to stratify patients for chemoprevention. The biomarker atypia was used to stratify women by risk. Random fine-needle aspiration (rFNA) and ductal lavage (DL) were evaluated and compared as the risk assessment tools used to discover atypia. Sensitivity analyses explore assumptions regarding the prognostic and predictive characteristics of atypia, both the relative breast cancer risk and benefit from chemoprevention women with atypia incur.

Results: Risk assessment strategies using rFNA or DL in combination with chemoprevention are found to be cost-effective (<$50,000 per life year saved) in high-risk groups under most scenarios. Both strategies were more effective and less costly in younger cohorts. Effectiveness of the risk assessment strategies increased when higher risk and increased benefit from chemoprevention were associated with atypia. Within the scenarios tested, rFNA is less costly than DL.

Conclusion: rFNA and DL appear to be cost-effective in high-risk women, assuming women with detected atypia choose tamoxifen. The tools are largely effective for women who are not motivated to take tamoxifen but would be if atypia were found. As biomarker risk assessment tools better predict the risk of breast cancer and or benefit of interventions, their cost-effectiveness increases.

Cervical cancer screening

Although primary prevention of human papillomavirus (HPV) infections that are causally associated with invasive cervical cancer may be within our grasp, it is unlikely that these approaches will replace existing cervical cancer screening strategies for many years. Experts agree and data support periodic cytology screening for young-adult women using one of several technologies. Recent analyses of cost-effectiveness suggest that the addition of molecular HPV DNA testing for women aged over 30 years may allow the screening interval to be lengthened to 3 years for most women. Women at high risk for HPV infection and its associated cellular atypias warrant closer monitoring and follow-up. These patients would include organ transplant recipients, women exposed to diethylstilbestrol (DES), and HIV-infected women.

Evaluating human papillomavirus vaccination programs

Human papillomavirus (HPV) has been implicated as the primary etiologic agent of cervical cancer. Potential vaccines against high-risk HPV types are in clinical trials. We evaluated vaccination programs with a vaccine against HPV-16 and HPV-18. We developed disease transmission models that estimated HPV prevalence and infection rates for the population overall, by age group, by level of sexual activity within each age group, and by sex. Data were based on clinical trials and published and unpublished sources. An HPV-16/18 vaccine for 12-year-old girls would reduce cohort cervical cancer cases by 61.8%, with a cost-effectiveness ratio of 14,583 dollars per quality-adjusted life year (QALY). Including male participants in a vaccine rollout would further reduce cervical cancer cases by 2.2% at an incremental cost-effectiveness ratio of 442,039 dollars/QALY compared to female-only vaccination. Vaccination against HPV-16 and HPV-18 can be cost-effective, although including male participants in a vaccination program is generally not cost-effective, compared to female-only vaccination.

Accuracy of visual screening for cervical neoplasia: Results from an IARC multicentre study in India and Africa

Visual inspection-based screening tests, such as visual inspection with 4% acetic acid (VIA) and with Lugol's iodine (VILI), have been proposed as alternatives to cytology in mass screening programs. To date, there is only limited information on the accuracy of these tests in detecting High-grade Squamous Intraepithelial Lesions (HSIL). Eleven cross-sectional studies involving 56,939 women aged 25-65 years were conducted in Burkina Faso, Congo, Guinea, India, Mali and Niger to evaluate the accuracy of VIA and VILI performed by health workers. A common protocol and questionnaire was used. For final diagnosis, all women were investigated with colposcopy and biopsies were taken when necessary. Data from the studies were pooled to calculate sensitivity, specificity and predictive values of the tests for the detection of HSIL. Of the screened women, 16.1% and 16.4% were positive on examination using, respectively, VIA and VILI; 1,063 were diagnosed with HSIL. The pooled sensitivity, specificity, positive and negative predictive values for VIA were 76.8% (95% CI: 74.2-79.4%), 85.5% (95% CI: 85.2-85.8%), 9.4% (95% CI:8.8-10.8%) and 99.5% (95% CI:99.4-99.6%), respectively. The values were 91.7% (95% CI: 89.7-93.4%), 85.4% (95% CI: 85.1-85.7%), 10.9% (95% CI: 10.2-11.6%) and 99.8% (95% CI:99.7-99.9%), respectively for VILI. The range of sensitivity and specificity for VIA was 56.1-93.9% and 74.2-93.8%, respectively, between studies and were 76.0-97.0 % and 73.0-91.3% for VILI. VILI had a significantly higher sensitivity than VIA in detecting HSIL, but specificity was similar. VILI appears to be a more accurate visual test for use in screening and treatment programs in low-resource settings.

Primary cervical cancer screening by self-sampling of human papillomavirus DNA in internal medicine outpatient clinics

BACKGROUND

We determined whether testing of self-collected vaginal swabs for human papillomavirus (HPV) DNA can be used to screen for cervical disease within internal medicine outpatient clinics.

PATIENTS AND METHODS

In this prospective study, 560 patients visiting two referral outpatient clinics for internal medicine were asked to take an HPV self-sample. Acceptability of self sampling, HPV prevalence and cervical intraepithelial neoplasia (CIN) detection rate were evaluated.

RESULTS

435 women (78%) performed HPV self-sampling; 1.5% considered self-sampling to be difficult. 134 women (31%) tested positive for high-risk type of HPV. There were significant differences between HPV-positive and -negative women with respect to the following: mean age (42 versus 46 years), number of women aged <16 years at first coitus (35% versus 23%) and history of drug abuse (8.3% versus 2.6%). Colposcopy could be performed for 70 HPV positive women: CIN 1-3 was identified in 24%. Two of 52 women with HPV-negative results undergoing colposcopy had biopsy-confirmed CIN 1. Test performance for detection of CIN 2-3 after correction for verification bias: sensitivity, 100%; specificity, 71%; negative predictive value, 100%; positive predictive value, 10%. HPV persistence was associated with a 5.7-fold risk of CIN 2-3 detection at follow-up.

CONCLUSIONS

Self-assessment for HPV DNA is an easy, feasible and well-accepted method for HPV testing and for cervical cancer screening in internal medicine outpatient clinics.

Effectiveness and Efficiency of Opportunistic Cervical Cancer Screening

BACKGROUND

Several countries have adopted nationally organized cervical screening programs, but many continue with opportunistic screening. Comparison of the effectiveness and efficiency of the 2 systems is important for informing policy.

OBJECTIVES

The objectives of this study were to assess the effectiveness and efficiency of an opportunistic cervical screening system, and to compare this with what could be achieved through an organized program.

RESEARCH DESIGN

We propose a model for estimating the effectiveness and efficiency of opportunistic screening systems and demonstrate it using data from a cross-sectional study of 1826 women in Hong Kong. We estimated the coverage and frequency of screening and used this to estimate effectiveness (number of cases of invasive cervical cancer potentially prevented) and efficiency (tests per case prevented) of the current system. Similar estimates were made for various organized programs with different screening intervals and coverage.

RESULTS

Ever screening coverage in this opportunistic system was 44%, resulting in 26% to 31% reduction in potential new cases (n = 144-183). Compared with this, a 3-yearly or 5-yearly screening policy aiming for 80% coverage would prevent an additional 46% (equivalent to 254 new cases out of a population of 2.3 million women per year) and 41% (222 per year), respectively. This could be achieved with more efficient use of resources, reducing the number of tests per case prevented from 2018 to 1545 and 1007, respectively.

CONCLUSIONS

At best, the effectiveness of this opportunistic system is equivalent to an organized program with 10-yearly screening and 50% coverage but at much greater cost. Poor coverage and over screening of a minority of women contributes to its inefficiency.

Cost-effectiveness analyses in gynecologic oncology: methodological quality and trends

OBJECTIVES

To evaluate methodological quality and trends of cost-effectiveness analyses (CEA) published in gynecologic oncology.

METHODS

A medical literature search of articles from 1966 through 2002 was performed to identify original, English-language articles that included economic analyses in gynecologic oncology. We included articles that were cost-effectiveness or cost-benefit analyses or performed these analyses as part of their study. Ten methodological principles that should be incorporated in CEAs were assessed for each study. Each article was given a score of 0, 1, or 2 for each of the 10 methodological principles (max score = 20). Data were analyzed using the Student t test, ANOVA, and linear regression.

RESULTS

We screened 693 articles to identify 68 that met our inclusion criteria. The articles focused on cervical cancer (n = 53; 78%), ovarian cancer (n = 11; 16%), uterine cancer (n = 2; 3%), and general perioperative care (n = 2; 3%). The mean (+/-SD) methodological principle score was 16.1 (+/-4.1) and we observed a significant improvement in the total score over time (P = 0.01). Primary CEA's (CEA identified as the objective of the study) were of higher quality than secondary CEA's (primary objective of the study was not CEA but CEA was included in the study; total scores 18.2 vs. 11.6, respectively; P<0.0001). Studies with at least one investigator in public health or healthcare economies also had higher quality (mean total score 17.7 vs. 15.2; P=0.006). The most common limitations of published CEAs were in methodology or presentation of incremental analyses, sensitivity analyses, and discounting.

CONCLUSIONS

Cost-effectiveness analyses in gynecologic oncology showed significant improvement in quality over the last two decades. Despite this progress, methodological improvement is still needed in the areas of incremental comparisons and sensitivity analysis. Understanding the methodology of cost-effectiveness analysis is critical for researchers, editors, and readers to accurately interpret results of the growing body of CEA articles.

Cost-effectiveness of human papillomavirus DNA testing for cervical cancer screening in women aged 30 years or more

OBJECTIVE

To evaluate the cost-effectiveness of human papillomavirus (HPV) DNA testing as a primary screening test in combination with cervical cytology in women aged 30 years or more.

METHODS

A state-transition mathematical model was used to simulate the natural history of HPV and cervical cancer in a cohort of U.S. women. Strategies included no screening and screening at different frequencies with conventional cytology, liquid-based cytology with HPV testing used for triage of equivocal results, and HPV DNA testing and cytology in combination after women had reached the age of 30. Outcomes measured included cancer incidence, life expectancy, lifetime costs, and incremental cost-effectiveness ratios.

RESULTS

The estimated reduction in lifetime risk of cervical cancer varies from 81% to 93% depending on the screening frequency, type of cytology, and test strategy. Every 3-year screening with liquid-based cytology administered to women at all ages and every 3-year screening using HPV DNA testing and cytology in combination administered to women aged 30 years or more provide equivalent or greater benefits than those provided by annual conventional cytology and have incremental cost-effectiveness ratios of US dollars 95300 and US dollars 228700 per year of life gained, respectively. In comparison, annual screening with HPV DNA testing and cytology in combination provides only a few hours of additional life expectancy and has a cost-effectiveness ratio of more than Us dollars 2000000 per year of life gained.

CONCLUSIONS

For women aged 30 years and more, every 2- or 3-year screening strategy that uses either HPV DNA testing in combination with cytology for primary screening or cytology with reflex HPV DNA testing for equivocal results will provide a greater reduction in cancer and be less costly than annual conventional cytology.

Projected Clinical Benefits and Cost-effectiveness of a Human Papillomavirus 16/18 Vaccine

BACKGROUND

Human papillomavirus (HPV) vaccine may be commercially available in a few years. We explored the clinical benefits and cost-effectiveness of introducing an HPV16/18 vaccine in a population with an organized cervical cancer screening program.

METHODS

A computer-based model of the natural history of HPV and cervical cancer was used to project cancer incidence and mortality, life expectancy (adjusted and unadjusted for quality of life), lifetime costs, and incremental cost-effectiveness ratios (i.e., the additional cost of a strategy divided by its additional clinical benefit compared with the next most expensive strategy) associated with different cancer prevention policies, including vaccination (initiated at age 12 years), cytologic screening (initiated at 18, 21, 25, 30, or 35 years), and combined vaccination and screening strategies. We assumed that vaccination was 90% effective in reducing the risk of persistent HPV16/18 infections and evaluated alternative assumptions about vaccine efficacy, waning immunity, and risk of replacement with non-16/18 HPV types.

RESULTS

Our model showed that the most effective strategy with an incremental cost-effectiveness ratio of less than 60 dollars-000 per quality-adjusted life year is one combining vaccination at age 12 years with triennial conventional cytologic screening beginning at age 25 years, compared with the next best strategy of vaccination and cytologic screening every 5 years beginning at age 21 years. This triennial strategy would reduce the absolute lifetime risk of cervical cancer by 94% compared with no intervention. These results were sensitive to alternative assumptions about the underlying patterns of cervical cancer screening, duration of vaccine efficacy, and natural history of HPV infection in older women.

CONCLUSIONS

Our model predicts that a vaccine that prevents persistent HPV16/18 infection will reduce the incidence of HPV16/18-associated cervical cancer, even in a setting of cytologic screening. A program of vaccination that permits a later age of screening initiation and a less frequent screening interval is likely to be a cost-effective use of health care resources.

Initial results from a randomized trial of cervical visual screening in rural south India

The impact of a single round of screening of visual inspection with acetic acid (VIA) on cervical cancer incidence and mortality was investigated in a cluster randomized trial in south India. Women 30-59 years of age in 113 clusters in Dindigul District were randomized to VIA screening (57 clusters, 48,225 women) by nurses and to a control group (56 clusters, 30,167 women). 30,577 eligible women were screened between May 2000 and April 2003; 2,939 (9.6%) screen-positive women were investigated with colposcopy by nurses and 2,777 (9.1%) women had biopsy. CIN 1 was diagnosed in 1,778 women, CIN 2-3 lesions were found in 222, and there were 69 screen detected invasive cervical cancers. The detection rates of lesions per 1,000 screened women were 58.2 for CIN 1, 7.3 for CIN 2-3, and 2.3 for invasive cancer. The detection rate of high-grade lesions in our study was 2-3-fold higher than those observed in repeatedly screened populations in developed countries. 71% of women with CIN 1 and 80% of those with CIN 2-3 lesions accepted cryotherapy provided by nurses and surgical treatment by mid-level clinicians. Overall, 97 and 34 incident cervical cancer cases were observed in the intervention and control arms, respectively. The intervention arm accrued 124,144 person years and the control arm accrued 90,172 during the study period. The age standardized cervical cancer incidence rates were 92.4/100,000 person-years in the intervention and 43.1/100,000 in the control arms. In the screened arm, 35.0% of cases were in Stage I as opposed to none in the control arm. The preliminary findings from our study indicate that not only is a VIA-based screening programme feasible, safe and acceptable to a population in rural settings, it also results in early detection of cervical neoplasia.

Direct Visual Inspection of the Cervix for the Detection of Premalignant Lesions

OBJECTIVE

To assess the feasibility and performance of direct visual inspection (DVI) of the cervix as a primary tool for the detection of premalignant lesions of the cervix (HPV/CIN 1 and CIN 2,3).

SETTING

The early cancer detection unit at the Ain Shams University Maternity Hospital in Cairo, Egypt.

SUBJECTS AND METHODS

The study included 2049 women. Cervical smears were obtained from all women for cytologic evaluation followed by direct visual inspection (DVI) of the cervix after painting with 5% acetic acid. Women whose smear reports showed abnormal cells suggestive of squamous intraepithelial lesion (SIL) or human papillomavirus (HPV) infection or those who showed abnormalities or acetowhite areas on direct visual inspection subsequently were referred for colposcopy and biopsy when appropriate. Colposcopy also was performed for women with negative DVI and negative smears if they had contact bleeding or chronic per vaginal discharge.

RESULTS

Mean (SD) age of women included in the study was 39.9 (10.2) years with their mean (SD) parity 2.9 (1.1). Results of DVI were normal in 1916 women (93.4%) and showed abnormal acetowhite appearance in 133 (6.6%) women. There were 458 (22.4%) colposcopic examinations and 130 biopsies (6.34%) were carried out, picking up 83 cases of premalignant lesions (4.0%). Premalignant lesions were 80 HPV/CIN 1 and CIN 2,3. Direct visual inspection detected 71 of the 83 premalignant lesions (sensitivity, 85.5%; specificity, 96.8%; positive predictive value, 52.6%). Direct visual inspection missed one of the three samples showing CIN 2,3. Cervical cytologic analysis showed abnormal cells in 60 (2.9%) and identified only 14 of the premalignant lesions (sensitivity, 16.9%; specificity, 97.8%; positive predictive value, 23.3%). Twelve of the premalignant lesions had positive smear results and a negative DVI, with none of them being of a high grade.

CONCLUSIONS

Direct visual inspection is feasible and had superior sensitivity compare with cervical cytologic analysis in detecting premalignant lesions of the cervix. Direct visual inspection can be used as a primary screening tool with a satisfactory low biopsy rate in low-resource settings or where cytologic services are suboptimal.

Chapter 10: Cervical cancer screening using visualization techniques

There is a resurgence of interest in the use of visual techniques to identify cervical intraepithelial neoplasia (CIN). These visual techniques can be divided into two general categories. One is the simple visual screening method, such as direct visual inspection (DVI), during which the cervix is visualized with either the naked eye or a low-power magnification device after the application of a solution of 3% to 5% acetic acid that is used as a chemical contrast agent to highlight regions of CIN. DVI has been evaluated in a number of large clinical trials and is considered by some to be a possible alternative to cervical cytology for primary cervical cancer screening in low-resource settings. The advantages of DVI compared with cervical cytology for these settings are that it is inexpensive, it does not require a laboratory infrastructure, and it provides an immediate result, allowing the use of "screen and treat" protocols. The major disadvantage of DVI is that it is relatively nonspecific and that its sensitivity is low compared with testing for human papillomavirus. The other category of visual techniques includes devices that use electro-optical sensors and light of specific wavelengths produced by lasers or specialized light sources to identify and localize regions of CIN on the cervix. Although these "high-technology" devices are not yet in routine clinical use, several groups and companies have such devices in clinical trials.

Chapter 15: Public health policy and cost-effectiveness analysis

Recent scientific advances are providing an opportunity to revisit strategies for cervical cancer prevention. How to invest health resources wisely, such that public health benefits are maximized-and opportunity costs are minimized-is a critical question in the setting of enhanced cytologic screening methods, human papillomavirus DNA testing, and vaccine development. Developing sound clinical guidelines and public health policy will require careful consideration of the incremental benefits, harms, and costs associated with new interventions compared with existing interventions, at both an individual and a population level. In addition to an intervention's effectiveness, public health decision making requires the consideration of its feasibility, sustainability, and affordability. No clinical trial or single cohort study will be able to simultaneously consider all of these components. Cost-effectiveness analysis and disease-simulation modeling, capitalizing on data from multiple sources, can serve as a valuable tool to extend the time horizon of clinical trials, to evaluate more strategies than possible in a single clinical trial, and to assess the relative costs and benefits of alternative policies to reduce mortality from cervical cancer.

Decision science and cervical cancer

Mathematical modeling is an effective tool for guiding cervical cancer screening, diagnosis, and treatment decisions for patients and policymakers. This article describes the use of mathematical modeling as outlined in five presentations from the Decision Science and Cervical Cancer session of the Second International Conference on Cervical Cancer held at The University of Texas M. D. Anderson Cancer Center, April 11-14, 2002. The authors provide an overview of mathematical modeling, especially decision analysis and cost-effectiveness analysis, and examples of how it can be used for clinical decision making regarding the prevention, diagnosis, and treatment of cervical cancer. Included are applications as well as theory regarding decision science and cervical cancer. Mathematical modeling can answer such questions as the optimal frequency for screening, the optimal age to stop screening, and the optimal way to diagnose cervical cancer. Results from one mathematical model demonstrated that a vaccine against high-risk strains of human papillomavirus was a cost-effective use of resources, and discussion of another model demonstrated the importance of collecting direct non-health care costs and time costs for cost-effectiveness analysis. Research presented indicated that care must be taken when applying the results of population-wide, cost-effectiveness analyses to reduce health disparities. Mathematical modeling can encompass a variety of theoretical and applied issues regarding decision science and cervical cancer. The ultimate objective of using decision-analytic and cost-effectiveness models is to identify ways to improve women's health at an economically reasonable cost.

A comprehensive natural history model of HPV infection and cervical cancer to estimate the clinical impact of a prophylactic HPV-16/18 vaccine

The object of our study is to project the impact of a prophylactic vaccine against persistent human papillomavirus (HPV)-16/18 infection on age-specific incidence of invasive cervical cancer. We developed a computer-based mathematical model of the natural history of cervical carcinogenesis to incorporate the underlying type-specific HPV distribution within precancerous lesions and invasive cancer. After defining plausible ranges for each parameter based on a comprehensive literature review, the model was calibrated to the best available population-based data. We projected the age-specific reduction in cervical cancer that would occur with a vaccine that reduced the probability of acquiring persistent infection with HPV 16/18, and explored the impact of alternative assumptions about vaccine efficacy and coverage, waning immunity and competing risks associated with non-16/18 HPV types in vaccinated women. The model predicted a peak age-specific cancer incidence of 90 per 100,000 in the 6th decade, a lifetime cancer risk of 3.7% and a reproducible representation of type-specific HPV within low and high-grade cervical precancerous lesions and cervical cancer. A vaccine that prevented 98% of persistent HPV 16/18 was associated with an approximate equivalent reduction in 16/18-associated cancer and a 51% reduction in total cervical cancer; the effect on total cancer was attenuated due to the competing risks associated with other oncogenic non-16/18 types. A vaccine that prevented 75% of persistent HPV 16/18 was associated with a 70% to 83% reduction in HPV-16/18 cancer cases. Similar effects were observed with high-grade squamous intraepithelial lesions (HSIL) although the impact of vaccination on the overall prevalence of HPV and low-grade squamous intraepithelial lesions (LSIL) was minimal. In conclusion, a prophylactic vaccine that prevents persistent HPV-16/18 infection can be expected to significantly reduce HPV-16/18-associated LSIL, HSIL and cervical cancer. The impact on overall prevalence of HPV or LSIL, however, may be minimal. Based on the relative importance of different parameters in the model, several priorities for future research were identified. These include a better understanding of the heterogeneity of vaccine response, the effect of type-specific vaccination on other HPV types and the degree to which vaccination effect persists over time.

Comparison between prototype hybrid capture 3 and hybrid capture 2 human papillomavirus DNA assays for detection of high-grade cervical intraepithelial neoplasia and cancer

We compared the performance of a prototype version of the Hybrid Capture 3 (HC3) human papillomavirus (HPV) DNA assay to the current generation Hybrid Capture 2 (HC2) assay, both of which target 13 oncogenic HPV types, for the detection of cervical intraepithelial neoplasia grade 3 and cancer (CIN3+) with cervicovaginal lavage specimens collected at enrollment into a 10-year cohort study at Kaiser Permanente (Portland, Oreg.). HC3 results for a risk-stratified sample (n = 4,364) were compared to HC2 results for the entire cohort (n = 20,810) with receiver operating characteristics curves, and the optimal cut points for both tests (relative light units [RLU]/positive control [PC]) for the detection of CIN3+ were determined. Specimens were also tested for HPV16 and HPV18 with separate HC3 type-specific probes. The optimal cut point for detecting CIN3+ was 1.0 RLU/PC for HC2, as previously shown, and was 0.6 RLU/PC for HC3. At the optimal cut points, HC3 and HC2 had similar screening performance characteristics for CIN3+ diagnosed at the enrollment visit. In analyses that included cases CIN3+ at enrollment and those diagnosed during early follow-up, HC3 had nonsignificantly higher sensitivity and equal specificity for the detection of CIN3+ compared to HC2; this increase in sensitivity was primarily the result of increased detection of CIN3+ in women who were 30 years of age or older and were cytologically negative (P = 0.006). We also compared the performance of the hybrid capture tests to MY09/11 L1 consensus primer PCR results (n = 1,247). HC3 was less likely than HC2 to test positive for specimens that tested positive by PCR for any untargeted types (P < 0.001). HC3 was less likely than HC2 to test positive for untargeted PCR-detected single infections with HPV53 (P = 0.001) and HPV66 (P = 0.01). There was good agreement between test positivity by PCR and by single type-specific HC3 probes for HPV16 (kappa = 0.76; 95% confidence interval [CI] = 0.71 to 0.82) and for HPV18 (kappa = 0.73; 95% CI = 0.68 to 0.79). In conclusion, we suggest that HC3 (>/=0.6 RLU/PC) may be slightly more sensitive than and equally specific test as HC2 (>/=1.0 RLU/PC) for the detection of CIN3+ over the duration of typical screening intervals.

Visual inspection with acetic acid and cytology in the early detection of cervical neoplasia in Kolkata, India

Visual inspection of the cervix after application of 3-5% acetic acid (VIA) is a potential alternative to cytology for screening in low-resource countries. The present study evaluated the performance of VIA, magnified visual inspection after application of acetic acid (VIAM), and cytology in the detection of high-grade cervical cancer precursor lesions in Kolkata (Calcutta) and suburbs in eastern India. Trained health workers with college education concurrently screened 5881 women aged 30-64 years with VIA, VIAM, and conventional cervical cytology. Detection of well-defined, opaque acetowhite lesions close to the squamocolumnar junction; well-defined, circumorificial acetowhite lesions; or dense acetowhitening of ulceroproliferative growth on the cervix constituted a positive VIA or VIAM. Cytology was considered positive if reported as mild dysplasia or worse lesions. All screened women (N = 5881) were evaluated by colposcopy, and biopsies were directed in those with colposcopic abnormalities (N = 1052, 17.9%). The final diagnosis was based on histology (if biopsies had been taken) or colposcopic findings, which allowed direct estimation of sensitivity, specificity, and predictive values. Moderate or severe dysplasia or carcinoma in situ (CIN 2-3 disease) was considered as true positive disease for the calculation of sensitivity, specificity, and predictive values of screening tests. 18.7%, 17.7% and 8.2% of the women tested positive for VIA, VIAM, and cytology. One hundred twenty two women had a final diagnosis of CIN 2-3 lesions. The sensitivities of VIA and VIAM to detect CIN 2-3 lesions were 55.7% and 60.7%, respectively; the specificities were 82.1% and 83.2%, respectively. The sensitivity and specificity of cytology were 29.5% and 92.3%, respectively. All the tests were associated with negative predictive values above 98%. VIA and VIAM had significantly higher sensitivity than cytology in our study; the specificity of cytology was higher than that of VIA and VIAM.

Human papillomavirus DNA testing as an adjunct to cytology in cervical screening programs

Our objective was to review current large studies of human papillomavirus (HPV) DNA testing as an adjunct to the Papanicolaou test for cervical cancer screening programs. We analyzed 10 large screening studies that used the Hybrid Capture 2 test and 3 studies that used the polymerase chain reaction test in a manner that enabled reliable estimates of accuracy for detecting or predicting high-grade cervical intraepithelial neoplasia (CIN). Most studies allowed comparison of HPV DNA and Papanicolaou testing and estimates of the performance of Papanicolaou and HPV DNA as combined tests. The studies were selected on the basis of a sufficient number of cases of high-grade CIN and cancer to provide meaningful statistical values. Investigators had to demonstrate the ability to generate reasonably reliable Hybrid Capture 2 or polymerase chain reaction data that were either minimally biased by nature of study design or that permitted analytical techniques for addressing issues of study bias to be applied. Studies had to provide data for the calculation of test sensitivity, specificity, predictive values, odds ratios, relative risks, confidence intervals, and other relevant measures. Final data were abstracted directly from published articles or estimated from descriptive statistics presented in the articles. In some studies, new analyses were performed from raw data supplied by the principal investigators. We concluded that HPV DNA testing was a more sensitive indicator for prevalent high-grade CIN than either conventional or liquid cytology. A combination of HPV DNA and Papanicolaou testing had almost 100% sensitivity and negative predictive value. The specificity of the combined tests was slightly lower than the specificity of the Papanicolaou test alone, but this decrease could potentially be offset by greater protection from neoplastic progression and cost savings available from extended screening intervals. One "double-negative" HPV DNA and Papanicolaou test indicated better prognostic assurance against risk of future CIN 3 than 3 subsequent negative conventional Papanicolaou tests and may safely allow 3-year screening intervals for such low-risk women.

Performance of visual inspection with acetic acid for cervical cancer screening: a qualitative summary of evidence to date

Developing countries often lack the necessary resources to use the Papanicolaou (Pap) smear as a screening tool for cervical abnormalities. Because the burden of cervical cancer is highest in such low-resource settings, alternative techniques have been sought. Recently, interest in visual inspection with acetic acid (VIA) has increased. Numerous studies have been conducted on its accuracy and its ability to detect cervical lesions when compared with other techniques, both conventional and nonconventional. This review summarizes key findings from the literature to provide researchers and policymakers with an up-to-date summary on VIA. PubMed was used to identify relevant journal articles published between 1982 and 2002. Key words were cervical cancer screening, visual inspection, VIA (visual inspection with acetic acid), DVI (direct visual inspection), AAT (acetic acid test), and cervicoscopy. Studies were eligible for review only if they involved analysis of primary VIA data (ie, not review articles); studies involving magnification devices were excluded. Fifteen studies were reviewed in total; key results were extracted and a summary analysis was performed for sensitivity and specificity parameters. When reported, sensitivity ranged between 66% and 96% and specificity between 64% and 98%. Authors comparing VIA with cytology noted that the overall usefulness of VIA compares favorably with that of the Pap test. The reported findings reviewed here suggest that VIA has the potential to be a cervical cancer screening tool, especially in low resource settings.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to describe how visual inspection of the cervix for cervical cancer screening (VIA) is performed, to summarize the current literature on VIA, and to list potential advantages of VIA.

Clinical and economic benefit of HPV-load testing in follow-up and management of women postcone biopsy for CIN2-3

This study aimed to evaluate the clinical and economic implications of integrating human papilloma virus (HPV) load testing into the follow-up and management protocol of women postconisation for high-grade cervical intraepithelial neoplasia (CIN2-3). We evaluated 130 suitable women: 63 were screened biannually by Pap smears ('conventional approach') and 67 also had HPV-load testing ('HPV approach'). More stringent criteria for undergoing colposcopy or reconisation were observed by the former group compared to the latter. Both approaches were analysed for cost effectiveness. There were 33 out of 67 (49.2%) colposcopic referrals and 24 out of 67 (35.8%) reconisation/hysterectomies with the 'conventional approach' compared to 9 out of 63 (14.2%) and 7 out of 63 (11.1%) with the 'HPV approach'. Cervical intraepithelial neoplasia 2-3 residual disease was detected in 7 out of 67 (10.5%) and 7 out of 63 (11.1%) women. The 'conventional approach' had more negative colposcopic biopsies and more negative reconisation/hysterectomy histologies than the 'HPV approach'. The respective cost per detection of one case of residual disease was US$3573 and US$3485. The 'HPV approach' required fewer colposcopic and reconisation procedures to detect one case of residual CIN2-3. Its higher positive predictive value than that of cytology provided a significant decrease in false positive rates and a reduction of US$88 per detected case.

Safety, acceptability, and feasibility of a single-visit approach to cervical-cancer prevention in rural Thailand: a demonstration project

BACKGROUND

To increase screening and treatment coverage, innovative approaches to cervical-cancer prevention are being investigated in rural Thailand. We assessed the value of a single-visit approach combining visual inspection of the cervix with acetic acid wash (VIA) and cryotherapy.

METHODS

12 trained nurses provided services in mobile (village health centre-based) and static (hospital-based) teams in four districts of Roi-et Province, Thailand. Over 7 months, 5999 women were tested by VIA. If they tested positive, after counselling about the benefits, potential risks, and probable side-effects they were offered cryotherapy. Data measuring safety, acceptability, feasibility, and effort to implement the programme were gathered.

FINDINGS

The VIA test-positive rate was 13.3% (798/5999), and 98.5% (609/618) of those eligible accepted immediate treatment. Overall, 756 women received cryotherapy, 629 (83.2%) of whom returned for their first follow-up visit. No major complications were recorded, and 33 (4.4%) of those treated returned for a perceived problem. Only 17 (2.2%) of the treated women needed clinical management other than reassurance about side-effects. Both VIA and cryotherapy were highly acceptable to the patients (over 95% expressed satisfaction with their experience). At their 1-year visit, the squamocolumnar junction was visible to the nurses, and the VIA test-negative rate was 94.3%.

INTERPRETATION

A single-visit approach with VIA and cryotherapy seems to be safe, acceptable, and feasible in rural Thailand, and is a potentially efficient method of cervical-cancer prevention in such settings.

Cost-effectiveness of a potential vaccine for human papillomavirus

Human papillomavirus (HPV) infection, usually a sexually transmitted disease, is a risk factor for cervical cancer. Given the substantial disease and death associated with HPV and cervical cancer, development of a prophylactic HPV vaccine is a public health priority. We evaluated the cost-effectiveness of vaccinating adolescent girls for high-risk HPV infections relative to current practice. A vaccine with a 75% probability of immunity against high-risk HPV infection resulted in a life-expectancy gain of 2.8 days or 4.0 quality-adjusted life days at a cost of $246 relative to current practice (incremental cost effectiveness of $22,755/quality-adjusted life year [QALY]). If all 12-year-old girls currently living in the United States were vaccinated, >1,300 deaths from cervical cancer would be averted during their lifetimes. Vaccination of girls against high-risk HPV is relatively cost effective even when vaccine efficacy is low. If the vaccine efficacy rate is 35%, the cost effectiveness increases to $52,398/QALY. Although gains in life expectancy may be modest at the individual level, population benefits are substantial.

Hepatic venous pressure gradient measurements to assess response to primary prophylaxis in patients with cirrhosis: a decision analytical study

BACKGROUND

The measurement of the hepatic venous pressure gradient may identify a suboptimal response to beta-blockers in patients with varices at risk for bleeding. However, the cost-effectiveness of routine hepatic venous pressure gradient measurements to guide primary prophylaxis has not been examined.

METHODS

We used decision analysis to evaluate two hepatic venous pressure gradient measurement strategies relative to standard beta-blocker therapy in a hypothetical cohort of patients with high-risk varices: (i) hepatic venous pressure gradient measurement 4 weeks after the initiation of beta-blocker therapy; and (ii) hepatic venous pressure gradient measurement prior to and 4 weeks after the initiation of beta-blocker therapy. The total expected costs, variceal bleeding episodes and deaths were calculated over a 1-year time horizon.

RESULTS

Beta-blocker therapy was associated with total costs of $1464, seven variceal bleeding episodes, one variceal bleeding episode-related death and 15 deaths. One hepatic venous pressure gradient measurement was associated with total costs of $5015, four variceal bleeding episodes, one variceal bleeding episode-related death and 15 deaths. Two hepatic venous pressure gradient measurements were associated with total costs of $8657, four episodes of variceal bleeding, one variceal bleeding episode-related death and 15 deaths. Compared with beta-blocker therapy alone, the incremental costs per variceal bleeding episode prevented and death averted were, respectively, $108 185 and $355 100 (one hepatic venous pressure gradient measurement) and $202 796 and $719 300 (two hepatic venous pressure gradient measurements). The results were sensitive to the time horizon of the analysis, the probability of bleeding whilst on beta-blockers and the cost of hepatic venous pressure gradient measurement.

CONCLUSION

Hepatic venous pressure gradient measurement to guide primary prophylaxis is an expensive strategy for reducing variceal bleeding or death, especially in patients with limited life expectancy, such as those with advanced, decompensated cirrhosis.

Cervical cancer control, priorities and new directions

Cervical cancer is caused by infection with a range of high risk "oncogenic" human papillomavirus (HPV) types, and it is now accepted that >99% of cervical cancer is initiated by HPV infection. The estimated lifetime risk of cervical cancer is nevertheless relatively low (less than 1 in 20 for most community based studies). Although sensitivity and specificity of the available diagnostic techniques are suboptimal, screening for persistent HPV infection is effective in reducing the incidence of cervical cancer. Infection can be detected by molecular techniques or by cytological examination of exfoliated cervical cells. Persistent infection is the single best predictor of risk of cervical cancer. The latest findings of HPV and cervical cancer research need to be widely disseminated to the scientific and medical societies that are updating screening and management protocols, public health professionals, and to women and clinicians. This report reviews current evidence, clinical implications and directions for further research in the prevention, control and management of cervical cancer. We report the conclusions of the Experts' Meeting at the EUROGIN 2003 conference.

Development of a clockwork light source to enable cervical inspection by village health workers

BACKGROUND: Cervical cancer can often be prevented by screening and may be curable if identified and treated in its early stages. However, 80% of new cases occur in less-developed countries where cervical cancer screening programmes are small-scale or non-existent. This is a human tragedy of great proportion, with many of those affected being young mothers. There is some evidence that cancerous or precancerous lesions may be detected by visual inspection with acetic acid (VIA) and field studies indicate that this technique is effective, safe and acceptable to women. However, the provision of a light source for inspection of the cervix presents a major problem in less-developed countries, where candles and torches often provide the only means of illumination. Our objective was to develop a light source based on clockwork technology, that required no batteries or external power source. METHODS: We adapted the design of a commercially available clockwork torch to provide a light source for cervical inspection. The light source was then tested under laboratory conditions in a comparison with other illumination methods typically used in this application. RESULTS: The light source gave illuminance levels greater than those produced by any other method tested, and also had considerable advantages in terms of ease of use and safety. CONCLUSION: This design is small, compact, effective and safe to use and promises a better and more affordable means of visualising the cervix. Further field trials of VIA are now required which incorporate this light source.

Use of visual screening methods for cervical cancer screening

This article has considered recent advances in visual screening methods. Devices that use electro-optical sensors offer great potential in various clinical roles, but considerable additional work is required to develop these devices and it is unlikely that they will come into widespread clinical use in the next 5 years. In contrast numerous studies, demonstrate that simple visual screening methods, such as DVI, have a sensitivity for the detection of women with biopsy-confirmed high-grade SIL (CIN 2,3) and cancer that is equivalent to that of conventional cervical cytology. The primary disadvantage of the simple visual screening methods is poor specificity. These methods classify up to 30% of all women screened as being test positive and as a result new strategies toward managing DVI positive women must be developed before simple visual screening methods can be adopted for routine screening. Enhanced visual methods that use cervicography and speculoscopy may be more specific and improve detection of biopsy-confirmed SIL, but the added time and expense to perform either of these methodologies must be considered and justified. Currently numerous studies are evaluating the best strategies for incorporating visual screening methods into cervical cancer screening programs. In the near future we should be able to determine whether these approaches should be incorporated into routine clinical care.

Paying for prevention standardizing the measurement of the value of health care interventions

It is not clear if spending more on tests that enhance the accuracy of Pap smears would lead to a greater reduction in cancer incidence than if the money were spent to include a greater proportion of women in primary screening. The cost effectiveness of tests beyond the Pap smear has not been clearly demonstrated. There is the question of whether cervical cancer incidence can be decreased more by improving the tests for patients who are already screened or by improving access to the unscreened population. Cervical cancer screening represents only one of many public health issues competing for resources. Given that there are choices to be made, the optimal yardstick against which all resource-competing programs are measured should be marginal benefit versus marginal cost.

Health economics and cervical cancer prevention: a global perspective

Recent scientific advances are providing an opportunity to revisit strategies for cervical cancer prevention. How to invest health resources wisely, such that clinical benefits are maximized-and opportunity costs are minimized-is a critical question in the setting of new technology. In addition to an intervention's effectiveness, public health decision-making requires consideration of its feasibility, sustainability and affordability. No clinical trial or single cohort study will be able to simultaneously consider all of these components. A mathematical simulation model can be a useful tool with which to evaluate alternative cervical cancer control strategies by extending the knowledge from empirical studies to real-world situations. Models combine information about the natural history of disease with other relevant demographic, epidemiological, and economic characteristics. We describe a comprehensive Cervical Cancer Policy Model with a flexible structure that may be modified as new data on the biology of disease become available. This model provides an analytic framework to synthesize data on costs and benefits, to help design clinical guidelines, and to inform development of sound health policy. Examples of cost-effectiveness analyses conducted in the US and South Africa illustrate inevitable tradeoffs when choosing among a variety of interventions to decrease cervical cancer mortality, and demonstrate how these methods can facilitate a bridge between research and health policy.

Quality assurance in screening strategies

The pre-requisites for successful screening programmes include understanding and acceptance of the necessity for tests with achieved high coverage of those at risk for the disease, provision of screening tests, provision of facilities for treatment of abnormalities, and acceptance by women of the necessity for further investigation of abnormalities, all requiring attention to quality assurance. Screening programmes for cancer of the cervix have been very effective in many developed countries but in very few developing countries. In general, the failures in developing countries can be directly related to failure to achieve adequate quality in one or other component of a programme. Some of these failures occur at the level of the laboratory, but in several Latin American countries, there are superb laboratories, but overall the programme has failed to achieve the expected impact. In some countries this has led to alternatives to the cytology smear being evaluated, without recognition that it is not the test that has failed, but another essential component of an effective programme. The solution is attention to management and organisation at all levels, with quality assurance at each. This is required at the level of: definition of the target population, identification of the individual women in the target population, recruitment of the at risk woman to screening, administration of the screening test, laboratory examination of the test, communication of results from the laboratory to the woman and her physician, ensuring the woman attends for investigation and management of abnormal screening tests, ensuring adequate therapy of lesions identified by the diagnostic process, ensuring adequate follow-up of treated women, ensuring women with negative screening tests return for re-screening at the appropriate intervals, and monitoring and evaluation of the programme.

Royal Society of Tropical Medicine and Hygiene meeting at Manson House, London 17 January 2002. Cervical cancer in developing countries

The public health importance of cervical cancer is now increasingly appreciated as a means to improve the general health of women in many developing countries. Developing countries account for 80% of the world burden, mostly due to the lack of effective control programmes. Infection with oncogenic types of human papillomaviruses (HPV) has been established as the central cause for cervical cancer. Thus, vaccination against HPV is a potentially useful strategy for prevention, but this may take several years to become a reality. Currently, early detection and treatment is the most effective approach to control cervical cancer. Cervical cancer may be controlled through improving awareness and accessibility to diagnostic and treatment services. Cytology-based screening is beyond the capacity of health services in many developing countries, hence, alternative methods to cytology are being investigated. Visual inspection of the cervix after application of 3-5% acetic acid (VIA) seems to be a promising screening test, with a similar sensitivity to that of cytology, but lower specificity. Currently, it is being evaluated for its cost-effectiveness in reducing cervical cancer incidence and mortality in randomized trials. Information from the ongoing studies will be valuable for evolving cervical cancer control policies and programmes in low-resource settings.