Chapter 10: Cervical cancer screening using visualization techniques

Comparison of In Vivo Study of Co-Polarized and Cross-Polarized Fluorescence Spectroscopy to Co-Minus Cross-Polarized Fluorescence Spectroscopy to Diagnose Precancerous Cervical Lesions by Handheld Probe

Background

In 2020, the number of new cases of cervix uteri was 604,127, i.e., 3.1% of all cancers, and the number of deaths was 341,831 (3.3%) among both sexes. In vivo fluorescence spectroscopy is an emerging optical technology that offers promise for the diagnosis of disease & has the capability to quickly, noninvasively and quantitatively probe the biochemical and morphological changes that occur as tissue becomes dysplastic.

Materials and Method

A cross-sectional observational study was conducted from December 2019 to September 2021 in the OBGY Department, UISEMH, in collaboration with optical imaging laboratory, BIOPHOTONICS, IIT Kanpur. A fabricated in-house fluorescence spectroscope consisting of a laser diode (405 nm) as light source and a miniature spectrometer is used to detect fluorescence signal from the sample. Patient's cervix was examined in the OPD, using an optical handheld probe, which functions on the principle of polarized fluorescence spectroscopy. The tissues were examined and classified on the basis of varying patterns of polarized spectroscopy (co-polarized, cross-polarized and co-minus cross-polarized light). The results were compared with that of cytological, colposcopy and histopathological findings and on various demographic variables.

Results and Conclusion

In vivo handheld probe based on polarized fluorescence spectroscopy is an excellent screening technique. Co- and cross- polarized light has shown enhanced accuracy. Accuracy of co-minus cross-polarized light is poor. It is fast, noninvasive and quantitative and, with further developments, has the potential to become a regular screening tool in future.

Review of the Standard and Advanced Screening, Staging Systems and Treatment Modalities for Cervical Cancer

Simple Summary

This review discusses the timeline and development of the recommended screening tests, diagnosis system, and therapeutics implemented in clinics for precancer and cancer of the uterine cervix. The incorporation of the latest automation, machine learning modules, and state-of-the-art technologies into these aspects are also discussed.

Abstract

Cancer arising from the uterine cervix is the fourth most common cause of cancer death among women worldwide. Almost 90% of cervical cancer mortality has occurred in low- and middle-income countries. One of the major aetiologies contributing to cervical cancer is the persistent infection by the cancer-causing types of the human papillomavirus. The disease is preventable if the premalignant lesion is detected early and managed effectively. In this review, we outlined the standard guidelines that have been introduced and implemented worldwide for decades, including the cytology, the HPV detection and genotyping, and the immunostaining of surrogate markers. In addition, the staging system used to classify the premalignancy and malignancy of the uterine cervix, as well as the safety and efficacy of the various treatment modalities in clinical trials for cervical cancers, are also discussed. In this millennial world, the advancements in computer-aided technology, including robotic modules and artificial intelligence (AI), are also incorporated into the screening, diagnostic, and treatment platforms. These innovations reduce the dependence on specialists and technologists, as well as the work burden and time incurred for sample processing. However, concerns over the practicality of these advancements remain, due to the high cost, lack of flexibility, and the judgment of a trained professional that is currently not replaceable by a machine.

Data-Driven Cervical Cancer Prediction Model with Outlier Detection and Over-Sampling Methods

Globally, cervical cancer remains as the foremost prevailing cancer in females. Hence, it is necessary to distinguish the importance of risk factors of cervical cancer to classify potential patients. The present work proposes a cervical cancer prediction model (CCPM) that offers early prediction of cervical cancer using risk factors as inputs. The CCPM first removes outliers by using outlier detection methods such as density-based spatial clustering of applications with noise (DBSCAN) and isolation forest (iForest) and by increasing the number of cases in the dataset in a balanced way, for example, through synthetic minority over-sampling technique (SMOTE) and SMOTE with Tomek link (SMOTETomek). Finally, it employs random forest (RF) as a classifier. Thus, CCPM lies on four scenarios: (1) DBSCAN + SMOTETomek + RF, (2) DBSCAN + SMOTE+ RF, (3) iForest + SMOTETomek + RF, and (4) iForest + SMOTE + RF. A dataset of 858 potential patients was used to validate the performance of the proposed method. We found that combinations of iForest with SMOTE and iForest with SMOTETomek provided better performances than those of DBSCAN with SMOTE and DBSCAN with SMOTETomek. We also observed that RF performed the best among several popular machine learning classifiers. Furthermore, the proposed CCPM showed better accuracy than previously proposed methods for forecasting cervical cancer. In addition, a mobile application that can collect cervical cancer risk factors data and provides results from CCPM is developed for instant and proper action at the initial stage of cervical cancer.

Quantitative Screening of Cervical Cancers for Low-Resource Settings: Pilot Study of Smartphone-Based Endoscopic Visual Inspection After Acetic Acid Using Machine Learning Techniques

BACKGROUND

Approximately 90% of global cervical cancer (CC) is mostly found in low- and middle-income countries. In most cases, CC can be detected early through routine screening programs, including a cytology-based test. However, it is logistically difficult to offer this program in low-resource settings due to limited resources and infrastructure, and few trained experts. A visual inspection following the application of acetic acid (VIA) has been widely promoted and is routinely recommended as a viable form of CC screening in resource-constrained countries. Digital images of the cervix have been acquired during VIA procedure with better quality assurance and visualization, leading to higher diagnostic accuracy and reduction of the variability of detection rate. However, a colposcope is bulky, expensive, electricity-dependent, and needs routine maintenance, and to confirm the grade of abnormality through its images, a specialist must be present. Recently, smartphone-based imaging systems have made a significant impact on the practice of medicine by offering a cost-effective, rapid, and noninvasive method of evaluation. Furthermore, computer-aided analyses, including image processing-based methods and machine learning techniques, have also shown great potential for a high impact on medicinal evaluations.

OBJECTIVE

In this study, we demonstrate a new quantitative CC screening technique and implement a machine learning algorithm for smartphone-based endoscopic VIA. We also evaluated the diagnostic performance and practicability of the approach based on the results compared to the gold standard and from physicians' interpretation.

METHODS

A smartphone-based endoscope system was developed and applied to the VIA screening. A total of 20 patients were recruited for this study to evaluate the system. Overall, five were healthy, and 15 were patients who had shown a low to high grade of cervical intraepithelial neoplasia (CIN) from both colposcopy and cytology tests. Endoscopic VIA images were obtained before a loop electrosurgical excision procedure for patients with abnormal tissues, and their histology tissues were collected. Endoscopic VIA images were assessed by four expert physicians relative to the gold standard of histopathology. Also, VIA features were extracted from multiple steps of image processing techniques to find the differences between abnormal (CIN2+) and normal (≤CIN1). By using the extracted features, the performance of different machine learning classifiers, such as k-nearest neighbors (KNN), support vector machine, and decision tree (DT), were compared to find the best algorithm for VIA. After determining the best performing classifying model, it was used to evaluate the screening performance of VIA.

RESULTS

An average accuracy of 78%, with a Cohen kappa of 0.571, was observed for the evaluation of the system by four physicians. Through image processing, 240 sliced images were obtained from the cervicogram at each clock position, and five features of VIA were extracted. Among the three models, KNN showed the best performance for finding VIA within holdout 10-fold cross-validation, with an accuracy of 78.3%, area under the curve of 0.807, a specificity of 80.3%, and a sensitivity of 75.0%, respectively. The trained model performed using an unprovided data set resulted in an accuracy of 80.8%, specificity of 84.1%, and sensitivity of 71.9%. Predictions were visualized with intuitive color labels, indicating the normal/abnormal tissue using a circular clock-type segmentation. Calculating the overlapped abnormal tissues between the gold standard and predicted value, the KNN model overperformed the average assessments of physicians for finding VIA.

CONCLUSIONS

We explored the potential of the smartphone-based endoscopic VIA as an evaluation technique and used the cervicogram to evaluate normal/abnormal tissue using machine learning techniques. The results of this study demonstrate its potential as a screening tool in low-resource settings.

Sexual activity and protection of reproductive health among female students

Introduction: Early sexual activity and multiple sex partners are leading risk factors for the development of sexually transmitted diseases and cervical cancer. Raising the level of knowledge about measures to protect reproductive health among young people can lead to significant reduction of same. Aim: Aim of the study is to determine sexual activity, knowledge and views on measures to protect reproductive health among female students on the University of Novi Sad. Material and methods: The survey was conducted among 269 female students, on Faculty of Philosophy, Faculty of Agriculture and Faculty of Medicine, University of Novi Sad (age 19-24 years), from December 2018. to February 2019. An anonymous questionnaire was used as the instrument for the research. Statistical analysis was carried out in SPSS Statistics 20. Results: Early sexual activity, before 18 years had 33.7% of respondents (average age 16.44). A number of 32% of students had one, and 13.4% had 4 sexual partners or more. Condom use 62.2% of students, but 8% of women don't use any protection. One-third of students knows that HPV infection can cause cervical cancer, 60.6% didn't even hear for a vaccine against it. There is a statistically significant difference in knowledge about reproductive health in terms of contraceptive methods between medical female students and female students on other faculties, as well. Conclusion: There is a significant percentage of female students who had early sexual activity and low knowledge about reproductive health. This points to the need for more intense sex education in order to raise the level of knowledge about measures to protect reproductive health.

Effectiveness of a two-stage strategy with HPV testing followed by visual inspection with acetic acid for cervical cancer screening in a low-income setting

The World Health Organization recently advocated a two-stage strategy with human papillomavirus (HPV) testing followed by visual inspection of the cervix with acetic acid (VIA) as a suitable option for cervical cancer screening. However, its accuracy has never been directly assessed in the context of primary screening. To evaluate effectiveness of HPV testing on self-obtained specimens (self-HPV) followed by VIA (sequential testing) in a low-income setting, we recruited 540 women aged between 30 and 65 years in two Cameroonian periurban areas. Eligible women were counseled about cervical cancer and how to perform self-sampling. HPV positive and a random sample of HPV-negative women were called back for VIA and biopsy. Disease was defined by interpretation of cervical intraepithelial neoplasia Grade 2 or worse (CIN2+). Performances of VIA, self-HPV and sequential testing were determined after adjustment for verification bias. HPV prevalence was 27.0%. VIA positivity was 12.9% and disease prevalence was 5%. Sensitivity and specificity of VIA for CIN2+ were 36.4% [95% confidence interval (CI): 15.2-64.6%] and 90.4% (95% CI: 85.4-93.7%), respectively. Sensitivity of self-HPV [100.0% (95% CI: 79.6-100.0%)] was 66% higher than that of sequential testing [33.3% (95% CI: 15.2-58.3%)]. Meanwhile, specificity of self-HPV [74.5% (95% CI: 70.6-78.1%)] was 22% lower than that of sequential testing [96.7% (95% CI: 94.8-97.9%)]. A two-stage screening strategy with self-HPV followed by VIA improves specificity of cervical cancer screening, but at the cost of an important loss of sensitivity. Ways to improve VIA performance or other tools are needed to increase positive predictive value of HPV testing.

Lessons learned from successful Papanicolaou cytology cervical cancer prevention in the Socialist Republic of Vietnam

In 1996, we documented that the burden of cervical cancer in Vietnam was associated with troop movements during the Vietnam War. Subsequently, establishment of Papanicolaou screening in southern Vietnam was associated with reductions in cervical cancer incidence from 29.2/100,000 in 1998 to 16/100,000 in 2003. This is one of the first English-language reports of a real-world cervical cancer prevention effort associated with a decisive impact on health outcomes in a contemporary developing country.

LESSONS LEARNED

if our ideological commitment is to improve health outcomes as rapidly as possible among as many people as possible, then Papanicolaou screening (with or without HPV or visual screening) must be implemented without further delay in any setting where cervical screening is appropriate but unavailable; consideration must be given to HPV vaccination after, rather than before, full coverage of target demographic groups by screening services has been achieved and/or the possibility has been excluded that HPV vaccination may be ineffective for cancer prevention. Competing ideological commitments engender imprudent yet commercially useful alternative strategies prone to decelerate global reductions in mortality by suppressing the more-rapid uptake of less-expensive open-source technology in favor of the less-rapid uptake of more-expensive proprietary technologies with uncertain real-world advantages and unfavorable real-world operational limitations. Global cervical cancer prevention efforts will become more effective if global health leaders, including the Bill & Melinda Gates Foundation, embrace an ideological commitment to improving health outcomes as rapidly as possible among as many people as possible and assimilate the policy implications of that commitment.

SOGC–GOC–SCC Joint Policy Statement. No. 255, March 2011. Cervical cancer prevention in low-resource settings

OBJECTIVE

To help care providers understand the current status of cervical cancer in low-resource countries.

OPTIONS

The most effective and practical options for cervical screening and treatment in low-resource countries are evaluated.

OUTCOMES

Improvement in rates of prevention and early detection of cervical cancer in low-resource countries.

EVIDENCE

PubMed or Medline, CINAHL, and The Cochrane Library were searched for studies published in English between January 2006 and December 2009. Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care. Recommendations for practice were ranked according to the method described in that report (Table). RECOMMENDATIONS 1. All girls 9 years old or over should have access to the cervical cancer vaccine before they become sexually active. (I-A) 2. Cervical cancer screening by visual inspection with acetic acid is suggested for low-resource settings acceptable. Cervical cytology or human papillomavirus testing may also be used when practical. (II-2B) 3. Cryotherapy is a safe, effective, and low-cost therapy that should be included in pre-invasive cervical cancer treatment. (III-B) 4. All countries should have a documented cervical cancer prevention strategy that includes public education built on existing outreach programs. (III-C) 5. Countries should define a centre or centres of excellence for the management of cervical cancer. (III-C) Because these units would serve a larger population, they would be able to identify leaders and develop their skills, and would be able to invest in costly radiation equipment. 6. All women with cervical cancer should have access to pain management. (III-C).

Cervical cancer risk factors and feasibility of visual inspection with acetic acid screening in Sudan

Objectives:

To assess the risk factors of cervical cancer and the feasibility and acceptability of a visual inspection with acetic acid (VIA) screening method in a primary health center in Khartoum, Sudan.

Methods:

A cross-sectional prospective pilot study of 100 asymptomatic women living in Khartoum State in Sudan was carried out from December 2008 to January 2009. The study was performed at the screening center in Khartoum. Six nurses and two physicians were trained by a gynecologic oncologist. The patients underwent a complete gynecological examination and filled in a questionnaire on risk factors and feasibility and acceptability. They were screened for cervical cancer by application of 3%–5% VIA. Women with a positive test were referred for colposcopy and treatment.

Results:

Sixteen percent of screened women were tested positive. Statistically significant associations were observed between being positive with VIA test and the following variables: uterine cervix laceration (odds ratio [OR] 18.6; 95% confidence interval [CI]: 4.64–74.8), assisted vaginal delivery (OR 13.2; 95% CI: 2.95–54.9), parity (OR 5.78; 95% CI: 1.41–23.7), female genital mutilation (OR 4.78; 95% CI: 1.13–20.1), and episiotomy (OR 5.25; 95% CI: 1.15–23.8). All these associations remained statistically significant after adjusting for age, educational level, employment, and potential confounding factors such as smoking, number of sexual partners, and use of contraceptive method. Furthermore, the VIA screening method was found to be feasible and acceptable to participants.

Conclusion:

This pilot study showed that women who have uterine cervix laceration, assisted vaginal delivery, female genital mutilation, or episiotomy are at an increased risk of cervical cancer. It also showed that VIA is a feasible and acceptable cervical cancer screening method in a primary health care setting.

Evaluation of a cervical cancer screening program based on HPV testing and LLETZ excision in a low resource setting

We conducted studies in Vanuatu to evaluate potential screening and treatment strategies to assist with control of cervical cancer. In a pilot study of 496 women, visual inspection and cytology were evaluated as screening tests for detection of CIN 2 or worse (CIN2+), observed in 21 of 206 subjects biopsied on the basis of abnormal visual inspection or cytology. Sensitivity of visual inspection with Lugol's Iodine for detection of CIN2+ on biopsy was 0.63, specificity was 0.32, and the positive predictive value was 0.09. For HSIL cytology, sensitivity was 0.99, specificity was 0.77, and the positive predictive value was 0.88. HSIL cytology was significantly more sensitive and had a significantly higher PPV for CIN 2+ than visual inspection (p<0.01). In a further study of 514 women, we compared testing for HR HPV and cytology as predictors of biopsy proven CIN 2+. Sensitivity of HSIL cytology for CIN2+ as established by loop excision of the cervix was 0.81, specificity was 0.94, and positive predictive value was 0.48. Sensitivity of a positive test for HR HPV for detection of CIN2+ was non-significantly different from cytology at 0.81, specificity was 0.94, and positive predictive value was 0.42. Combining the two tests gave a significantly lower sensitivity of 0.63, a specificity of 0.98, and a positive predictive value of 0.68. For women over 30 in a low resource setting without access to cytology, a single locally conducted test for high risk HPV with effective intervention could reduce cervical cancer risk as effectively as intervention based on cytology conducted in an accredited laboratory.

Determinants of VIA (Visual Inspection of the Cervix After Acetic Acid Application) positivity in cervical cancer screening of women in a peri-urban area in Andhra Pradesh, India

OBJECTIVES

Visual inspection of the cervix after acetic acid application (VIA) is widely recommended as the method of choice in cervical cancer screening programs in resource-limited settings because of its simplicity and ability to link with immediate treatment. In testing the effectiveness of VIA, human papillomavirus DNA testing, and Pap cytology in a population-based study in a peri-urban area in Andhra Pradesh, India, we found the sensitivity of VIA for detection of cervical intraepithelial neoplasia grade 2 and worse (CIN2+) to be 26.3%, much lower than the 60% to 90% reported in the literature. We therefore investigated the determinants of VIA positivity in our study population.

METHODS

We evaluated VIA positivity by demographics and reproductive history, results of clinical examination, and results from the other screening methods.

RESULTS

Of the 19 women diagnosed with CIN2+, only 5 were positive by VIA (positive predictive value, 3.1%). In multivariate analysis, VIA positivity (12.74%) was associated with older age, positive Pap smear, visually apparent cervical inflammation, and interobserver variation. Cervical inflammation of unknown cause was present in 21.62% of women. In disease-negative women, cervical inflammation was associated with an increase in VIA positivity from 6.1% to 15.5% (P<0.001). Among the six gynecologists who performed VIA, the positivity rate varied from 4% to 31%.

CONCLUSIONS

The interpretation of VIA is subjective and its performance cannot be readily evaluated against objective standards.

IMPACT

VIA is not a robust screening test and we caution against its use as the primary screening test in resource-limited regions.

Automated and interactive lesion detection and segmentation in uterine cervix images

This paper presents a procedure for automatic extraction and segmentation of a class-specific object (or region) by learning class-specific boundaries. We describe and evaluate the method with a specific focus on the detection of lesion regions in uterine cervix images. The watershed segmentation map of the input image is modeled using a Markov random field (MRF) in which watershed regions correspond to binary random variables indicating whether the region is part of the lesion tissue or not. The local pairwise factors on the arcs of the watershed map indicate whether the arc is part of the object boundary. The factors are based on supervised learning of a visual word distribution. The final lesion region segmentation is obtained using a loopy belief propagation applied to the watershed arc-level MRF. Experimental results on real data show state-of-the-art segmentation results on this very challenging task that, if necessary, can be interactively enhanced.

Impact of patient adherence and test performance on the cost-effectiveness of cervical cancer screening in developing countries: the case of Honduras

OBJECTIVE

We examined the impact of patient adherence and screening test performance on the cost-effectiveness of visual inspection with acetic acid (VIA) and Pap smears when used with colposcopy for diagnosis.

MATERIALS AND METHODS

Cost-effectiveness analysis was performed using computer modeling. The primary outcome was cancer prevalence in the 10 years after screening. Three hypothetical populations of 35-year-old women were compared: never-screened women, women screened with VIA, and women screened with Pap smears. We used community-based data from our screening program in Honduras to estimate screening test sensitivity and specificity, adherence to follow-up, and costs of screening and colposcopy services. Published data were used to model disease outcomes.

RESULTS

VIA was more sensitive than Pap smears (70% vs. 4%), less expensive (U.S. 0.23 dollars vs. 3.17 dollars), and the 2-vist VIA system had a higher rate of adherence to follow-up than the 3-visit Pap smear system (84% vs. 38%). VIA had a higher false-positive rate than Pap smears resulting in higher colposcopy referral rates, but more dysplasia was detected and treated. Cost-effectiveness analysis revealed that screening with VIA would cost U.S. 3,198 dollars per cancer case avoided and reduce cancer cases by 42%, versus U.S. 36,802 dollars and 2% for Pap screening. Although Pap smear quality was low in Honduras, sensitivity analysis showed that VIA was more cost-effective than Pap smears, even when test accuracy was equivalent.

CONCLUSION

In developing countries, systems barriers can limit the cost-effectiveness of Pap smears. VIA may be a cost-effective alternative for some resource-poor settings, although systems barriers, quality control, and feasibility issues must be considered.

Quantitative physiology of the precancerous cervix in vivo through optical spectroscopy

Cervical cancer is the second most common female cancer worldwide. The ability to quantify physiological and morphological changes in the cervix is not only useful in the diagnosis of cervical precancers but also important in aiding the design of cost-effective detection systems for use in developing countries that lack well-established screening and diagnostic programs. We assessed the capability of a diffuse reflectance spectroscopy technique to identify contrasts in optical biomarkers that vary with different grades of cervical intraepithelial neoplasia (CIN) from normal cervical tissues. The technology consists of an optical probe and an instrument (with broadband light source, dispersive element, and detector), and a Monte Carlo algorithm to extract optical biomarker contributions including total hemoglobin (Hb) concentration, Hb saturation, and reduced scattering coefficient from the measured spectra. Among 38 patients and 89 sites examined, 46 squamous normal sites, 18 CIN 1, and 15 CIN 2(+) sites were included in the analysis. Total Hb was statistically higher in CIN 2(+) (18.3 +/- 3.6 microM, mean +/- SE) compared with normal (9.58 +/- 1.91 microM) and CIN 1 (12.8 +/- 2.6 microM), whereas scattering was significantly reduced in CIN 1 (8.3 +/- 0.8 cm(-1)) and CIN 2(+) (8.6 +/- 1.0 cm(-1)) compared with normal (10.2 +/- 1.1 cm(-1)). Hemoglobin saturation was not significantly altered in CIN 2(+) compared with normal and CIN 1. The difference in total Hb is likely because of stromal angiogenesis, whereas decreased scattering can be attributed to breakdown of collagen network in the cervical stroma.

Cervical cancer: a call for political will

Cervical cancer kills over a quarter of a million women worldwide on an annual basis, with 80% of these deaths occurring in developing countries. Cytology-based screening programs, widely used in industrialized countries, are difficult to implement in low-resource settings. Non-cytological methods for screening and treatment have been developed and studied over the last decade. Given the barriers to widespread, good quality screening and early treatment, the most promising new prevention strategy will be the introduction of a vaccine to prevent human papillomavirus infection, the cause of cervical cancer. Understanding women's health-seeking behaviors is critical to successful dissemination and uptake of both screening and vaccine prevention strategies.

Screening for cervical carcinoma using visual inspection with acetic acid

OBJECTIVE

To assess the performance of visual inspection with acetic acid (VIA) as a screening test for early detection of cervical carcinoma in the Dakahlia Governorate in Egypt.

METHODS

Diluted acetic acid (5%) was applied to the cervix during routine gynecologic examination. Women with positive results were referred for colposcopy. Those with negative results were referred for colposcopy only when they had clinical indications.

RESULTS

Among the 5,000 women who were screened using VIA, 409 were referred for colposcopy. Cervical intraepithelial neoplasia (CIN) was diagnosed in 151 (60%) of the 253 women with positive screening results and in 4 of the 156 women with negative screening results. There were 39 women with high-grade and 116 with low-grade CIN. The sensitivity and negative predictive value of the VIA screening test was 97%. Its positive predictive value was 60% for all grades of CIN and 90% for high-grade CIN.

CONCLUSION

Visual inspection with acetic acid, although associated with a relatively high rate of false-positive results, is a valuable test for the screening of cervical carcinoma.

The costs of reducing loss to follow-up in South African cervical cancer screening

Background

This study was designed to quantify the resources used in reestablishing contact with women who missed their scheduled cervical cancer screening visits and to assess the success of this effort in reducing loss to follow-up in a developing country setting.

Methods

Women were enrolled in this Cape Town, South Africa-based screening study between 2000 and 2003, and all had scheduled follow-up visits in 2003. Community health worker (CHW) time, vehicle use, maintenance, and depreciation were estimated from weekly logs and cost accounting systems. The percentage of women who attended their scheduled visit, those who attended after CHW contact(s), and those who never returned despite attempted contact(s) were determined. The number of CHW visits per woman was also estimated.

Results

3,711 visits were scheduled in 2003. Of these, 2,321 (62.5%) occurred without CHW contact, 918 (24.8%) occurred after contact(s), and 472 (12.7%) did not occur despite contact(s). Loss to follow-up was reduced from 21% to 6%, 39% to 10%, and 50% to 24% for 6, 12, and 24-month visits. CHWs attempted 3,200 contacts in 530 trips. On average, 3 CHWs attempted to contact 6 participants over each 111 minute trip. The per-person cost (2003 Rand) for these activities was 12.75, 24.92, and 40.50 for 6, 12, and 24-month visits.

Conclusion

CHW contact with women who missed scheduled visits increased their return rate. Cost-effectiveness analyses aimed at policy decisions about cervical cancer screening in developing countries should incorporate these findings.

Preventing cervical cancer in low-resource settings: how far have we come and what does the future hold?

The Alliance for Cervical Cancer Prevention (ACCP) came together in 1999 to answer key research questions and to advocate for greater global and national interest in reducing the heavy burden of morbidity and mortality caused by this preventable disease. Visual inspection with acetic acid (VIA), visual inspection with Lugol's iodine (VILI), and human papillomavirus (HPV) tests have been shown to be viable alternatives to traditional cytology. ACCP experience confirmed that cryotherapy is a safe and effective method that is acceptable to women and can be delivered by a range of health providers, including nonphysicians. Programs can maximize coverage by accommodating local needs and involving community leaders and women in planning and implementation. Advocacy efforts have led to significant policy changes and galvanized support for cervical cancer prevention. Despite the prospect of new HPV vaccines, screening will be needed for at least the next 30-40 years. Our experience has shown that with creativity, flexibility, and well-focused use of resources, the inequitable burden of cervical cancer borne by women in poor countries can be sharply reduced.

Human papillomavirus infection: biology, epidemiology, and prevention

Over the past several decades, knowledge of the biology and epidemiology of human papillomavirus (HPV) infection has increased tremendously. However, there are still many unanswered questions concerning the interaction of the virus with its host. The virus has been identified as a necessary causal agent for cervical squamous neoplasia and has been linked to the development of neoplasia in several other mucosal sites. The viral oncogenes E6 and E7 are the major players in the virus' scheme to evade the immune system and use the host cell replication machinery to survive. Many risk factors for infection with HPV have been identified; however, the focus now centers on identifying risk factors for persistence of the infection as it is likely that transient infections play a very small role in the overall development of clinical disease. Prevention measures to date have centered around screening programs, mostly for cervical cancer, including the perfection of screening techniques and inclusion of molecular testing for HPV into screening regimens. The development of prophylactic and therapeutic vaccines has also increased as primary prevention measures appear to have the best hope for long-term effects on cancer incidence.

A cluster randomized controlled trial of visual, cytology and human papillomavirus screening for cancer of the cervix in rural India

The impact of screening by visual inspection with acetic acid (VIA), cytology or HPV testing on cervical cancer incidence and mortality is investigated in a cluster randomized controlled trial in India. We report findings after the screening phase, when 52 clusters, with a total of 142,701 women aged 30-59 years in Osmanabad District, India, were randomized into 4 arms for a single round of screening by trained midwives with either VIA, cytology or HPV testing as well as a control group. All laboratory tests were done locally. Test-positive women underwent investigations (colposcopy/biopsy) and treatment in the base hospital. Data on participation, test positivity, positive predictive value and detection rates of cervical neoplasia were analyzed using cluster design methodology. Of the eligible women, 72-74% were screened. Test positivity rates were 14.0% for VIA, 7.0% for cytology and 10.3% for HPV. The detection rate of high-grade lesions was similar in all intervention arms (0.7% for VIA, 1.0% for cytology and 0.9% for HPV testing) (p = 0.06, Mann-Whitney test). While the detection rate for VIA dropped to 0.5% with declining test positivity during the course of the study, it remained constant for cytology and HPV testing. Over 85% of women with high-grade lesions received treatment. Our results show that a high level of participation and good-quality cytology can be achieved in low-resource settings. VIA is a useful alternative but requires careful monitoring. Detection rates obtained by HPV testing were similar to cytology, despite higher investments.

Screening for cancer: Valuable or not?

Screening for cancer has become extremely common. The evidence supporting screening for breast, colon, and cervix cancer is strong, but it is unclear for skin cancer, problematic for prostate cancer, and ineffective for lung cancer. Despite the problems associated with many screening approaches for cancer, enthusiasm by the medical profession and the public remains high. The objective analysis for the major tumor types is presented in this review, but the ultimate decision on whether to be screened lies in the personal and societal arena of values.