Acetic-acid guided visual inspection vs. cytology-based screening for cervical cancer in the Philippines

Diagnostic accuracy for alternative cervical cancer screening strategies: A systematic review and meta-analysis

We performed a systematic review and meta-analysis to evaluate the accuracy of screening cervical cancer tests as alternative standalone methods. The combined estimates of sensitivity of visual inspection with acetic acid, visual inspection with lugol's iodine, conventional pap smear, liquid-based cytology, High risk HPV testing by clinician, High risk HPV testing by self- sampling, cervicography were 64%, 80%, 55%, 70%, 70% and 67% respectively; the combine values of specificity of these screening strategies were 88%, 88%, 96%, 59%, 94%, and 95% respectively. Our findings draw attention to an attractive opinion to facilitate the collection of specimens for DNA HPV by patients in settings where they don't have access to a regular screening programs.

[Analysis of uterus cervical cancer screening campaign results in Conakry, Guinea]

OBJECTIVE

Reduce morbidity and death rates of women with cervical cancer in Guinea.

METHODOLOGY

This was a five-day cross-sectional study carried out in two successive years (2012 and 2013) at the CERFFO-PCG in Conakry. The target population was women aged 25-49. Approximately 500 women for 2012 and 900 women were expected in these cervical screening campaigns by visual methods (IVA and IVL) with immediate treatment of precancerous lesions. After histologic confirmation of the cancer lesions, the management was carried out according to the protocols in force in the country. We performed a simple descriptive analysis and the results expressed as a percentage and on average.

RESULTS

The target population represented 60.4% in 2012 and 76.2% in 2013, of the total number of women received. The incidence rate of high-grade intraepithelial lesions and cancers increased from 2.6% in 2012 to 0.9% in 2013. In 2012, the 57 precancerous lesions were treated with immediate treatment and 10 cases of cancers out of the 16 had a surgical treatment. Also in 2013, all precancerous lesions were treated immediately and 2 cancers out of the 4 benefited from surgery.

CONCLUSION

Our research shows that, with creativity, flexibility, good organization and efficient use of resources, morbidity and death rates of women with cervical cancer in a very resources can be significantly reduced.

Evaluation of multiple primary and combination screening strategies in postmenopausal women for detection of cervical cancer in China

As China's population ages, the importance of determining prevalence of cervical disease and accurate cervical cancer screening strategies for postmenopausal women is increasing. Seventeen population-based studies were analyzed to determine prevalence of cervical neoplasia in postmenopausal women. All women underwent HPV DNA testing, visual inspection with acetic acid (VIA) and cytology testing. Diagnostic values for primary and combinations screening methods included sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), referral rate and area under curve (AUC) were calculated using directed biopsy or four quadrants biopsy as reference standard. Premenopausal and postmenopausal women had equal HPV infection and cervical neoplasia rates (p > 0.05). HPV DNA testing CIN3+ sensitivity, specificity, PPV, NPV, referral rate and AUC were 97.9% (95% CI: 90.2-99.9%), 84.2% (95% CI: 82.8-85.5%), 9.9% (95% CI: 7.4-12.8%), 100% (95% CI: 99.8-100%), 17.2% (95% CI: 15.9-18.7%), 0.911, respectively. VIA values were 41.7% (95% CI: 28.4-55.9%), 94.5% (95% CI: 93.6-95.3%), 11.8% (95% CI: 7.5-17.3%), 98.9% (95% CI: 98.5-99.3%), 6.2% (95% CI: 5.3-7.1%) and 0.681, respectively. Values for VIA with HPV triage were 39.6% (95% CI: 26.6-53.8%), 99.2% (95% CI: 98.8-99.5%), 45.2% (95% CI: 30.8-60.4%), 98.9% (95% CI: 98.5-99.3%), 1.5% (95% CI: 1.1-2.0%) and 0.694, respectively. VIA and HPV DNA co-test values were 100% (95% CI: 94.0-100%), 79.5% (95% CI: 78.0-81.0%), 8.0% (95% CI: 6.0-10.3%), 100% (95% CI: 99.9-100%), 21.9% (95% CI: 20.4-23.4%) and 0.898, respectively. VIA sensitivity decreases significantly in postmenopausal women compared to premenopausal performance. HPV DNA testing maintains performance between pre- and postmenopausal women and is the most accurate primary modality for screening postmenopausal populations in low resource areas of China.

A cost-utility analysis of cervical cancer screening and human papillomavirus vaccination in the Philippines

Background

Cervical cancer is the second leading cause of cancer cases and deaths among Filipino women because of inadequate access to screening and treatment services.  This study aims to evaluate the health and economic benefits of HPV vaccination and its combination with different screening strategies to find the most optimal preventive strategy in the Philippines.

Methods

A cost-utility analysis was conducted using an existing semi-Markov model to evaluate different screening (i.e., Pap smear, visual inspection with acetic acid) and vaccination strategies against HPV infection implemented alone or as part of a combination strategy at different coverage scenarios. The model was run using country-specific epidemiologic, cost and clinical parameters from a health system perspective. Sensitivity analysis was performed for vaccine efficacy, duration of protection and costs of vaccination, screening and treatment.

Results

Across all coverage scenarios, VIA has been shown to be a dominant and cost-saving screening strategy with incremental cost-effectiveness ratio (ICER) ranging from dominant to Php 61,059 (1443 USD) per QALY gained. VIA can reduce cervical cancer cases and deaths by 25 %. Pap smear screening was found to be not cost-effective due to its high cost in the Philippines. Adding HPV vaccination at a cost of 54 USD per vaccinated girl on top of VIA screening was found to be potentially cost-effective using a threshold of 1 GDP per capita (i.e., Php 120,000 or 2835 USD/ QALY) with the most favorable assumption of providing lifelong immunity against high-risk oncogenic HPV types 16/18. The highest incremental QALY gain was achieved with 80 % coverage of the combined strategy of VIA at 35 to 45 years old done every five years following vaccination at 11 years of age with an ICER of Php 33,126 (783 USD). This strategy may result in a two-thirds reduction in cervical cancer burden. HPV vaccination is not cost-effective when vaccine protection lasts for less than 20 years.

Conclusion

High VIA coverage targeting women aged 35–45 years old at five-year intervals is the most efficient and cost-saving strategy in reducing cervical cancer burden in the Philippines. Adding a vaccination program at high coverage among 11-year-old girls is potentially cost-effective in the Philippines assuming a life-long duration of vaccine efficacy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-2046-1) contains supplementary material, which is available to authorized users.

Accuracy of visual inspection with acetic acid and with Lugol's iodine for cervical cancer screening: Meta-analysis

The aim of this review was to provide an updated summary estimation of the accuracy of visual inspection with acetic acid (VIA) and with Lugol's iodine (VILI) in detecting cervical cancer and precancer. Studies on VIA/VILI accuracy were eligible in which VIA/VILI was performed on asymptomatic women who all underwent confirmatory testing of histology, combination of colposcopy and histology, or combination of multiple screening tests, colposcopy and histology, to detect cervical intraepithelial neoplasia grade 2 or worse (CIN2+ or CIN3+). A bivariate model was fitted to estimate the accuracy of VIA/VILI and provide estimates of heterogeneity. Subgroup analysis was used to investigate the source of heterogeneity. A total of 29 studies on VIA and 19 studies on VILI were included finally in the meta-analysis. The summary sensitivity and specificity of VIA for CIN2+ were 73.2% (95%CI: 66.5-80.0%) and 86.7% (95%CI: 82.9-90.4%), respectively, and those for VILI were 88.1% (95%CI: 81.5-94.7%) and 85.9% (95%CI: 81.7-90.0%), respectively. VIA and VILI were both more sensitive in detecting more severe outcome, although there was a slight loss in specificity. Apparent heterogeneity existed in sensitivity and specificity for both VIA and VILI. High sensitivity of both VIA and VILI for CIN2+ was found when a combination of colposcopy and histology was used as disease confirmation. VIA, VILI, even a combination of them in parallel, could be good options for cervical screening in low-resource settings. Significant differences in sensitivity between different gold standards might provide a proxy for optimization of ongoing cervical cancer screening programs.

Diagnosing cervical dysplasia using visual inspection of the cervix with acetic acid in a woman in rural Haiti

Cervical cancer remains a significant cause of morbidity and mortality for women in developing countries, despite the fact that inexpensive, simple and effective screening methods are available. Visual inspection of the cervix with acetic acid (VIA) can be used as part of a "screen and treat" program to identify precancerous lesions for cryotherapy treatment. This case report details how the VIA screening test was incorporated into the care of a patient presenting to a maternal health clinic in Thomonde, Haiti which was staffed by doctors and medical students from Emory University School of Medicine in collaboration with Haiti Medishare. As demonstrated here, the VIA test requires minimal materials, can be efficiently incorporated into a physical exams, provides immediate results, and is easily demonstrated to and performed by local healthcare providers. The straightforward and sensitive VIA technique is an ideal cervical cancer screening method for resource poor areas.

Comparison between visual inspection of cervix and cytology based screening procedures in Bangladesh

BACKGROUND

Cervical cancer continues to be a major problem in Bangladesh with approximately 18,000 new cases annually of which over 10,000 women die from it. Visual inspection of the cervix after 3-5% acetic acid (VIA) application is a simple and easy to learn method for cervical cancer screening, although cytology-based screening is more often applied in developed countries where it has successfully reduced the prevalence of cervical cancer.

OBJECTIVE

To compare the efficacy of VIA and cytology-based primary methods for cervical cancer screening in Bangladesh.

MATERIALS AND METHODS

This hospital based comparative study was conducted at the VIA centre and Colposcopy Clinic of Bangabandhu Sheikh Mujib Medical University (BSMMU) from October 2008 to October 2010.

RESULTS

Among 650 women, 74 (11.4%) were VIA+ve and 8 (1.2%) had abnormalities in their Pap smear reports. During colposcopy, 38 (7.7%) women had different grades of CIN and 4 (0.6%) had cervical cancer. The gold standard histology findings proved 20 women had CIN I, 14 had CIN II/II and 4 had cervical cancer. Among the 38 histology diagnosed abnormalities, VIA test could identify 30 abnormalities including two cervical cancers. However, Pap smear could detect only 8 cases of histological abnormalities (2 low grade and 6 had high grade lesion) and it missed all the cervical cancer cases. The sensitivity and specificity of VIA were 88.9% and 52.1%. The positive predictive value (PPV) and negative predictive value (NPV) were 41.0%, and 92.6% respectively. Moreover, the sensitivity, specificity, PPV and NPV of Pap smear were 33.3%, 95.8%, 75.0% and 79.3%, respectively.

CONCLUSIONS

VIA test should be used as the primary screening tool even with its low sensitivity and specificity in low resource countries like Bangladesh. False positive results may be greater, but overtreatment can be minimized by colposcopy evaluation of the VIA positive women.

Comparing Papanicolau smear, visual inspection with acetic acid and human papillomavirus cervical cancer screening methods among HIV-positive women by immune status and antiretroviral therapy

BACKGROUND

A rigorous comparison of cervical cancer screening methods utilizing data on immune status, antiretroviral therapy (ART) and colposcopy-directed biopsy has not been performed among HIV-positive women.

METHODS

Between June and November 2009, 500 HIV-positive women were enrolled at an HIV treatment clinic in Nairobi, Kenya, and underwent Papanicolau (Pap) smear, visual inspection with acetic acid (VIA), human papillomavirus (HPV) and colposcopy-directed biopsy (gold standard). Positive Pap smear (ASCUS+, LSIL+, HSIL+), VIA, HPV and their combinations were compared with CIN2/3+. Sensitivity, specificity and AUC (sensitivity and 1-specificity) were compared using pairwise tests and multivariate logistic regression models that included age, CD4⁺ cell count and ART duration.

RESULTS

Of 500 enrolled, 498 samples were collected. On histology, there were 172 (35%) normal, 186 (37%) CIN1, 66 (13%) CIN2, 47 (9%) CIN3 and 27 (5%) indeterminate. Pap (ASCUS+) was the most sensitive screening method (92.7%), combination of both Pap (HSIL+) and VIA positive was the most specific (99.1%) and Pap (HSIL+) had the highest AUC (0.85). In multivariate analyses, CD4⁺ cell count of 350 cells/μl or less was associated with decreased HPV specificity (P = 0.002); ART duration of less than 2 years was associated with decreased HPV (P = 0.01) and VIA (P = 0.03) specificity; and age less than 40 years was associated with increased VIA sensitivity (P < 0.001) and decreased HPV specificity (P = 0.005).

CONCLUSION

Pap smear is a robust test among HIV-positive women regardless of immune status or ART duration. Results should be cautiously interpreted when using HPV among those younger, immunosuppressed or on ART less than 2 years, and when using VIA among those aged 40 years or more.

Measurement in comparative effectiveness research

Comparative effectiveness research (CER) on preventive services can shape policy and help patients, their providers, and public health practitioners select regimens and programs for disease prevention. Patients and providers need information about the relative effectiveness of various regimens they may choose. Decision makers need information about the relative effectiveness of various programs to offer or recommend. The goal of this paper is to define and differentiate measures of relative effectiveness of regimens and programs for disease prevention. Cancer screening is used to demonstrate how these measures differ in an example of two hypothetical screening regimens and programs. Conceptually and algebraically defined measures of relative regimen and program effectiveness also are presented. The measures evaluate preventive services that range from individual tests through organized, population-wide prevention programs. Examples illustrate how effective screening regimens may not result in effective screening programs and how measures can vary across subgroups and settings. Both regimen and program relative effectiveness measures assess benefits of prevention services in real-world settings, but each addresses different scientific and policy questions. As the body of CER grows, a common lexicon for various measures of relative effectiveness becomes increasingly important to facilitate communication and shared understanding among researchers, healthcare providers, patients, and policymakers.

Accuracy of several cervical screening strategies for early detection of cervical cancer: a meta-analysis

OBJECTIVE

The objectives of this study were to assess the accuracy of 6 common cervical screening strategies, including visual inspection with acetic acid, with a magnifying device, or with Lugol iodine (VILI), human papillomavirus testing with Hybrid Capture 2 assay, conventional Papanicolaou smear, and thin liquid-based cytology (LBC), and then to compare data obtained by the aforementioned 6 strategies.

METHODS

PubMed, EMBASE, and The Cochrane Library were systematically searched for all original relevant studies about early detection of cervical cancer. A meta-analysis was performed to evaluate the accuracy of the 6 screening strategies covering sensitivity, specificity, diagnostic odds ratio, and the area under the receiver operating characteristic curve.

RESULTS

Fifteen articles containing 22 cross-sectional studies were finally identified. The combined estimates of sensitivity for visual inspection with acetic acid, magnified visual inspection with acetic acid, VILI, Hybrid Capture 2 assay, conventional Papanicolaou smear, and LBC were 77%, 64%, 91%, 74%, 59%, and 88%, respectively; the combined values of specificity of these screening strategies were 87%, 86%, 85%, 92%, 94%, and 88%, respectively; the diagnostic odds ratio were 22.43, 10.30, 57.44, 33.26, 22.49, and 51.56, respectively; and the area under the receiver operating characteristic curve were 0.8918, 0.7737, 0.9365, 0.9486, 0.9079, and 0.9418, respectively.

CONCLUSIONS

This meta-analysis suggests that LBC appeared to be promising in primary cervical cancer screening in resourced regions, and VILI might be a good choice to identify/exclude cervical cancerous and precancerous lesions in resource-constrained regions.

Comparison of Papanicolaou test with visual detection tests in screening for cervical cancer and developing the optimal strategy for low resource settings

OBJECTIVES

To compare the sensitivity, specificity, positive and negative predictive values, and accuracy of Papanicolaou test with visual inspection with acetic acid (VIA)/VIA using magnification devices (VIAM) and develop the best strategy for screening in low resource settings.

MATERIALS AND METHODS

This is a prospective cross-sectional study on 408 symptomatic multiparous women in the reproductive age group, sequentially using the Papanicolaou test, the VIA, and the VIAM for screening. Women with a positive screening test underwent guided biopsy and endocervical curettage. The site of biopsy was recorded. Histopathological findings were taken as the "gold" standard in comparing the methods.

RESULTS

The mean (SD) age was 32.3 (6.8) years (range, 15-49 years), whereas the mean (SD) parity was 2.9 (1.2) (range, 1-9). Abnormal cytological findings were detected in 2.9% patients, whereas the remaining smears were negative for any intraepithelial lesion or malignancy. A total of 113 cases were screened positive by one/all methods. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the Papanicolaou test, the VIA, and the VIAM were 24, 98, 42, 96, and 94%; 95, 78, 19, 99, and 79%; and 95, 78, 19, 99, and 79%, respectively, for high-grade lesions.

CONCLUSIONS

The Papanicolaou test had low sensitivity but high specificity, whereas visual detection methods had a high sensitivity in addition to being cheaper. Alternative methods of screening such as VIA/VIAM can be a valuable alternative to the Papanicolaou test for cervical cancer screening in low resource settings. Visual inspection using magnification devices may be of benefit over VIA in doubtful cases.

Comparative study of four candidate strategies to detect cervical cancer in different health care settings

AIM

Considering the differing but potentially supplementary properties of visual inspection of the cervix with acetic acid (VIA) and the cytological examination (CYTO) of cervical smears for the screening of cervical cancers, we examined the performance of these two tests and their combinations for the screening of cervical cancer in different health care settings.

METHODS

In this cross-sectional diagnostic test performance evaluation study of 4235 female subjects in the reproductive age group, we assessed the screening performance of four strategies: VIA alone, CYTO alone, VIA and CYTO combined in a parallel fashion, and VIA and CYTO combined in tandem. Subjects were recruited from three settings: Hospital, Urban Community and Rural Community. Colposcopy was used as the reference standard. Screening performance was assessed using sensitivity, specificity, post-test probabilities and likelihood ratios (LR), diagnostic odds, area under receiver operating characteristic curve and LR chi(2).

RESULTS

Both VIA and CYTO when used alone had a low sensitivity but high specificity, especially in the Rural Community setting. A combination of the results of VIA and CYTO improved the diagnostic accuracy but the strategy using a parallel combination of VIA and CYTO was the most accurate. In general, all screening strategies using VIA and CYTO showed a modest screening performance.

CONCLUSIONS

In the settings of varying levels of health care and low resources, caution is needed for a generalized use of VIA for cervical cancer screening. Further evaluation of the cost-effective ways of combining VIA and CYTO is needed in these circumstances.

Determinants of womens participation in cervical cancer screening trial, Maharashtra, India

OBJECTIVE

To determine the factors associated with participation in cervical cancer screening and follow-up treatment in the context of a randomized controlled trial. The trial was initiated to evaluate the efficacy and cost effectiveness of visual inspection with acetic acid, cytological screening and testing for human papillomavirus in reducing the incidence of and mortality from cervical cancer in Maharashtra, India.

METHODS

Between October 1999 and November 2003 women aged 30-59 years were randomized to receive one of the three tests or to a control group. Participation was analysed for all three intervention arms. The differences between those who were screened versus those who were not was analysed according to the sociodemographic characteristics of the 100,800 eligible women invited for screening. Those who were treated versus those who were not were analysed according to the sociodemographic characteristics of the 932 women diagnosed with high-grade lesions. Participation in screening and compliance with treatment were also analysed according to the type of test used.

FINDINGS

Compared with women who were not tested, screened women were younger (aged 30-39), better educated and had ever used contraception. A higher proportion of screened women were married and a lower proportion had never been pregnant. Of the 932 women diagnosed with high-grade lesions or invasive cancer, 85.3% (795) received treatment. Women with higher levels of education, who had had fewer pregnancies and those who were married were more likely to comply with treatment. There were no differences in rates of screening or compliance with treatment when results were analysed by the test received.

CONCLUSIONS

Irrespective of the test being used, good participation levels for cervical cancer screening can be achieved in rural areas of developing countries by using appropriate strategies to deliver services. Communication methods and delivery strategies aimed at encouraging older, less-educated women, who have less contact with reproductive services, are needed to further increase screening uptake.

Alternative cervical cancer prevention in low-resource settings: Experiences of visual inspection by acetic acid with single-visit approach in the first five provinces of Thailand

BACKGROUND

After the confirmation of its safety, acceptability and feasibility in a cervical cancer prevention demonstration project in 2002, a visual inspection by acetic acid (VIA) followed by an effective treatment using cryotherapy as a single-visit approach (SVA) was recently introduced in five provinces having low Pap smear screening rates, in Thailand. The effectiveness of a screening program is usually associated with a high level of coverage; however, in low-resource settings such a high coverage is still hard to attain by the conventional Pap smear approach.

AIMS

To evaluate whether VIA/SVA can increase women's access to the prevention services in low-resource provinces of Thailand.

METHODS

A cross-sectional study was conducted by analysing electronic screening records of the provinces. A chi2 test was used in the comparisons of screening coverage between the year before and the first year of VIA/SVA implementation during 1998-2005.

RESULTS

This comparative study, which included 88 554 screening visits totally, shows a significant increase in the screening coverage of five provinces after the VIA/SVA implementation (P < 0.001). As a result of the large substitution of VIA/SVA for Pap smears, the costs of screening were lowered by as much as $US362,300 (66.8%) in the first year.

CONCLUSION

VIA/SVA has provided good screening coverage and lowered the financial burden in five low-resource provinces of Thailand. Therefore, it is promisingly competitive as a potential alternative means of cervical cancer prevention in low-resource areas.

Assessment of 2 Cervical Screening Methods in Mongolia

OBJECTIVE

The aim of the study was to evaluate the test parameters of visual inspection with acetic acid (VIA) and cervical cytology in 3 Mongolian aimags.

METHODS

From February 18, 2002, to December 12, 2004, sexually active women, 30 years or older who had never been screened, underwent cervical cytology and VIA in the aimags' central hospital. Women with abnormal test results and 5% of women with normal results were recommended to have colposcopy with or without biopsy.

RESULTS

Two thousand nine women underwent both tests. Visual inspection with acetic acid was abnormal in 254 (12.6%); Pap smear showed atypical squamous cells of undetermined significance or worse in 3%. Using cervical intraepithelial neoplasia 2 or higher disease on biopsy as the end point, the test parameters for VIA are sensitivity of 82.9% (95% CI = 81.3%-84.5%), specificity of 88.6% (95% CI = 87.2%-90.0%), positive predictive value of 12.2% (95% CI = 10.8%-13.6%), and negative predicative value of 99.7% (95% CI = 99.5%-99.9%). The test parameters for Pap smear are sensitivity of 88.6% (95% CI = 87.2%-90.0%), specificity of 98.5% (95% CI = 98.0%-99.0%), positive predictive value of 51.7% (95% CI = 49.5%-53.9%), and negative predicative value of 99.8% (95% CI = 99.6%-100%).

CONCLUSION

Visual inspection with acetic acid has an acceptable test parameter for population-based cervical screening in Mongolia.

Screening for Cervical Neoplasia in an Unselected Rural Guatemalan Population Using Direct Visual Inspection after Acetic Acid Application: A Pilot Study

OBJECTIVE

To assess the acceptability of cervical screening using direct visual inspection after acetic acid application followed by immediate cryotherapy for cervical intraepithelial neoplasia among women in rural Guatemala.

MATERIALS AND METHODS

An unselected group of 1,052 women voluntarily registered to undergo cervical screening using direct visual inspection of the cervix after acetic acid application. Women with acetowhite changes consistent with cervical intraepithelial neoplasia were offered immediate cryotherapy.

RESULTS

Cervical screening was deferred in 80 (7.6%) registrants, and 18 (1.7%) refused to undergo an examination. Among the 954 registrants screened, 125 (13%) had findings consistent with cervical intraepithelial neoplasia. Cryotherapy was deferred in three patients. A total of 121 (99%) women agreed to immediate cryotherapy.

CONCLUSION

Direct cervical visualization after acetic acid application followed by immediate cryotherapy for acetowhite changes consistent with cervical intraepithelial neoplasia would be a well-accepted method of cervical screening in rural Guatemala.

Screening test accuracy studies: how valid are our conclusions? Application to visual inspection methods for cervical screening

While the basic concepts associated with screening are simple, studying the value of new tests requires a very strict methodology. This paper summarizes lessons learned regarding appropriate methodologies to assess the value of new screening approaches using visual inspection with acetic acid (VIA), a screening test for cervical pre-cancerous lesions, as an example. In addition to being convenient to, safe for and acceptable by target community members, a screening test should be reliable and have good test characteristics (i.e. be able to discriminate well between early disease and non disease). Test reliability assesses the degree to which repeated measurements of the test yields the same result. To ensure reproducibility of study findings, test reliability should be assessed before any evaluation of test accuracy. The accuracy of a test (specificity and sensitivity) is measured using cross-sectional studies with adequate sample size. Several basic features are necessary to ensure internal validity for such studies: (a) final disease status data should be obtained for all subjects, (b) all tests results must be determined independently of previous results, (c) the reference standard used to determine the disease status should be accurate, (d) the full "spectrum" of the disease should be included in the study. The study results should also have external validity to be applicable to other populations to which the test will be applied. All these consideration are exemplified by 17 very heterogeneous studies published to date assessing VIA test accuracy. The assessment of a new screening test is the first step in researching a new cancer prevention strategy. For this reason, this step should be carefully addressed through rigorous studies.

Can we substitute brush cytology for biopsy in the evaluation of cervical lesions under the guidance of colposcopy?

In cervical cancer screening, colposcopically directed biopsy is the gold standard method for identifying intraepithelial and occult invasive lesions of the uterine cervix. As biopsy needs special expertise and the procedure is not convenient for the patients, we sought to evaluate colposcopically directed brush cytology as a substitute for biopsy of cervical lesions. We studied a series of 150 women who were referred for colposcopic evaluation. Colposcopically directed brush cytology and biopsy were performed for all patients with abnormal colposcopic findings. A total of 40 samples were excluded due to unsatisfactory report of brush cytology. Of the remaining 110 samples, 34 abnormal pathologies were reported in biopsy evaluations, while only 9 abnormal cytologies were reported in brush cytology specimens. Brush cytology sensitivity and specificity were 26% and 97%, respectively. We conclude that colposcopically directed brush cytology is not a safe substitute for biopsy in the evaluation of cervical lesions.

Screening for cervical cancer in the developing world

Cervical cancer remains the most common malignancy amongst females in countries of low income, mainly due to a lack of screening. Responsible factors are centred around inadequacies of the Pap smear: high cost; low sensitivity; the need of a laboratory with high human expertise; and a demanding logistic system for mass screening. No alternative screening method seems to be clearly advantageous. Although combinations of tests have higher sensitivities, they are complex, costly and associated with low specificities. Adding the problem of effective treatment, it seems that mass screening with adequate coverage of the population is an unreachable goal for many developing countries. The most promising development in the control of cervical cancer seems to be vaccination against the human papillomavirus, either as a preventative measure or for stimulating immunity in infected women.