A critical assessment of screening methods for cervical neoplasia

Cervical cancer prevention--cervical screening: science in evolution

The incidence and mortality of cervical cancer in the United States has declined by more than 70% since the 1950s. This decline is attributed mainly to the introduction of Papanicolaou's test in the 1940s. Cervical cancer, however, remains the second most frequent of all female malignancies worldwide, with 80% of the cases occurring in resource-poor countries. This disparity is attributed primarily to the lack of screening and treatment of precancerous lesions. This article describes the traditional methods of screening for cervical cancer and innovative methods that might help overcome financial and cultural barriers to more widespread screening.

Effectiveness of cryotherapy treatment for cervical intraepithelial neoplasia

OBJECTIVE

To assess the effectiveness of cryotherapy treatment delivered by general practitioners in primary care settings, as part of a screen-and-treat approach for cervical cancer prevention.

METHOD

Women aged between 25 and 49 years residing in San Martin, Peru, who were positive on visual inspection screening were treated, if eligible, with cryotherapy following biopsy. At 12 months post cryotherapy treatment the participants were evaluated for treatment effectiveness and examined by visual inspection and Papanicolaou test and, if positive, referred to a gynecologist for colposcopy and biopsy.

RESULTS

Cryotherapy treatment was performed for 1398 women; of these, 531 (38%) had a histology result of cervical intraepithelial neoplasia (CIN). Cryotherapy effectively cured CIN in 418 (88%) women, including 49 (70%) women with a baseline diagnosis of CIN 3.

CONCLUSION

Cryotherapy is an effective treatment for cervical precancerous lesions; it can easily be administered by general practitioners in primary care settings following visual inspection screening.

Emerging biomarkers in the detection, diagnosis and management of cervical dysplasia and carcinoma

Despite the success of widespread screening, cervical cancers continue to occur. Recently, the role of human papillomavirus (HPV) in cervical carcinogenesis has been firmly established. HPV prophylactic vaccines are expected to eradicate ∼ 70% of cervical cancers. An HPV test was demonstrated to improve the sensitivity of cytology and prolong the screening interval safely. Type-specific HPV testing will play an important role in the detection and follow up of cervical neoplastic lesions, as well as monitoring the efficacy of HPV vaccines. The combined use of cell proliferation markers with cytology can improve sensitivity, and some molecular markers seem to be related to the degree of dysplasia. Further studies are needed to evaluate the use of biomarkers in clinical settings.

Knowledge dissemination and evaluation in a cervical cancer screening implementation program in Nigeria

OBJECTIVES

Our goals were to train health professionals in Nigeria using the text, "Planning and Implementing Cervical Cancer Prevention and Control Programs: A Manual for Managers", and then evaluate the knowledge dissemination process using a pre- and post-test assessment. The manual was developed by the ACCP, WHO, IARC, PATH, Engender Health, JHPIEGO, and PAHO with funding from the Gates Foundation. It is an inclusive guide to implementation and maintenance of screen-and-treat cervical cancer prevention clinics and is ideally suited for programs operating in the developing world.

METHODS

Training took place at a conference in Ibadan, Nigeria. Participants included teams of physicians, nurses, bioengineers, data managers, and administrators who met in joint and parallel sessions to "train the trainers". This meeting was designed to provide both training and equipment to personnel to be involved in the implementation of a cervical cancer control initiative in Nigeria. A 36 item pre-test was administered prior to a group study sessions. A slide presentation summarized salient points before the post-test was given. The results were entered into an MS Excel spreadsheet for descriptive statistics about (1) the participants, (2) the test, (3) an examination of profession, years of work experience, years of education, and gender as predictors of two outcomes (low pre-test score and large difference between pre- and post-tests) and (4) overall performance on the exam.

RESULTS

There were 70 participants and trainers, of which 53 took the exam. Most of the examinees were physicians. Some participants did not fill out the post-test, leaving their tests inevaluable. A closer look at the test revealed eight questions that were confusing and nine that were too easy. All participant subgroups performed better on the post-test than the pre-test; the improvements were statistically significant. While profession impacted the results, profession was not statistically significant. Years of work experience, years of education, and gender did not affect test results.

CONCLUSIONS

While the study suffers from a small sample size, a few ambiguous questions, and the need for pilot testing the instrument prior to the meeting, the report evaluates the manual very favorably. The authors showed a significant gain in knowledge. The manual gives "the big picture" and does so with clarity. The text and supplementary material outline the work that needs to proceed in an organized program, and the material was easily understandable in Nigeria. Future evaluations could benefit from more participants and varied learning structures.

Persistence of human papillomavirus as a predictor for treatment failure after loop electrosurgical excision procedure

We aimed to investigate whether postconization human papillomavirus (HPV) DNA testing can predict treatment failure and improve the accuracy of conventional follow-up in women with high-grade cervical intraepithelial neoplasia (CIN). Between March 2001 and October 2005, 120 patients with confirmed CIN 2 or 3 were treated with loop electrosurgical excision procedure (LEEP) and were enrolled. Six patients were lost to the follow-up. Postconization follow-up was performed at every 3–6 months during the first year and then annually. Specimens were tested for the presence of HPV, using the Hybrid Capture 2 (Digene Co, Gaithersburg, MD) and HPV DNA chip (Mygene Co, Seoul, Korea) test. Persistent HPV infection was defined as persistently (two times or more) positive HPV tests with the same HPV subtype(s) at initial diagnosis. Twenty-two (19.3%) patients showed treatment failure after conization. The only significant risk factor for redevelopment of CIN after conization was persistence of the same HPV subtype (P< 0.0001). And women with recurrent or residual CIN had higher HPV load during the 6-month follow-up postconization. In conclusion, the persistence of the same HPV subtype after LEEP conization was an important predictor of treatment failure. The follow-up protocol after conization of CIN should include both cervical cytology and HPV test, and HPV DNA chip test is needed to detect a persistent HPV infection.

Vaccines against human papillomavirus: perspectives for controlling cervical cancer

Prophylactic vaccines against human papillomavirus (HPV) are on the market and will certainly reduce the incidence of genital warts and the risk of developing cervical cancer. In addition, they will contribute to reducing anal as well as head and neck cancers. However, effort should be made in the short term in order for these vaccines to have a real impact in the developing world, where almost 80% of cervical cancer cases occur. Since the available vaccines include only two of the HPV types found in cancers (approximately 70%), improvements in current mass screening programs - with the use of molecular techniques - must be made, particularly in developing countries. Therapeutic vaccines have been designed to control advanced lesions and residual illness and, although success has usually been obtained in animal models, clinical studies have not yet provided the anticipated results. Finally, the next generations of prophylactic HPV vaccines will probably include subunit vaccines, transgenic bacteria and plants, among others, and could represent useful and cheaper alternatives for reducing cervical cancer, particularly in the developing world.

Effect of visual screening on cervical cancer incidence and mortality in Tamil Nadu, India: a cluster-randomised trial

BACKGROUND

Cervical cancer is the most common cancer among women in developing countries. We assessed the effect of screening using visual inspection with 4% acetic acid (VIA) on cervical cancer incidence and mortality in a cluster randomised controlled trial in India.

METHODS

Of the 114 study clusters in Dindigul district, India, 57 were randomised to one round of VIA by trained nurses, and 57 to a control group. Healthy women aged 30 to 59 years were eligible for the study. Screen-positive women had colposcopy, directed biopsies, and, where appropriate, cryotherapy by nurses during the screening visit. Those with larger precancerous lesions or invasive cancers were referred for appropriate investigations and treatment. Cervical cancer incidence and mortality in the study groups were analysed and compared using Cox regression taking the cluster design into account, and analysis was by intention to treat. The primary outcome measures were cervical cancer incidence and mortality.

RESULTS

Of the 49,311 eligible women in the intervention group, 31,343 (63.6%) were screened during 2000-03; 30,958 control women received the standard care. Of the 3088 (9.9%) screened positive, 3052 had colposcopy, and 2539 directed biopsy. Of the 1874 women with precancerous lesions in the intervention group, 72% received treatment. In the intervention group, 274,430 person years, 167 cervical cancer cases, and 83 cervical cancer deaths were accrued compared with 178,781 person-years, 158 cases, and 92 deaths and in the control group during 2000-06 (incidence hazard ratio 0.75 [95% CI 0.55-0.95] and mortality hazard ratio 0.65 [0.47-0.89]).

INTERPRETATION

VIA screening, in the presence of good training and sustained quality assurance, is an effective method to prevent cervical cancer in developing countries.

Comparability of self-collected vaginal swabs and physician-collected cervical swabs for detection of human papillomavirus infections in Rakai, Uganda

OBJECTIVE

The objective of this study was to compare human papillomavirus (HPV) DNA testing between self-administered vaginal swabs and physician-administered cervical swabs in women from rural Rakai District, Uganda.

STUDY DESIGN

Between 2002 and 2003, women from a population-based cohort participated in an HPV study. Women collected self-administered vaginal swabs and were also offered a pelvic examination, which included physician-collected cervical samples.

METHODS

Hybrid-capture 2 was used to determine carcinogenic HPV status. Polymerase chain reaction was used to determine HPV genotypes. Unweighted kappa statistics were used to determine agreement.

RESULTS

Compliance with self-collected swabs was > or =86%; however, only 51% accepted a pelvic examination. Carcinogenic HPV prevalence was 19% in self-collected and 19% in physician-collected samples. Agreement among paired observations was 92% with a kappa of 0.75. Kappa between self- and physician-collected samples was similar in HIV strata (k = 0.71 and 0.75 for HIV-positive and HIV-negative, respectively).

DISCUSSION

In this community-based setting, detection of carcinogenic HPV was comparable among self- and physician-administered samples. Self-collection is a feasible and accurate means of obtaining HPV samples from women in resource-poor settings or persons reluctant to undergo a pelvic examination.

Progression and regression of incident cervical HPV 6, 11, 16 and 18 infections in young women

BACKGROUND

We describe type-specific progression, regression and persistence of incident human papillomavirus (HPV)-6-11-16 and -18 infections, along with type distribution in cervical intra-epithelial neoplasia (CIN) lesions.

METHODS

The study population consisted of 16-23 year-old women undergoing Pap testing and cervical swab polymerase chain reaction testing for HPV DNA at approximate 6 month intervals for up to 4 years in the placebo arm of a clinical trial of an HPV 16-vaccine. HPV types in incident infections were correlated with types in lesion biopsy specimens.

RESULTS

56.7% of CIN-1 and nearly one-third of CIN-2/3 lesions following incident HPV-6-11-16 or -18 infections did not correlate with the incident infection HPV type. Cumulative 36-month progression rates to CIN-2/3 testing positive for the relevant HPV type were highest for HPV-16 infections (16.5%), followed by HPV-18 (8.2%). Overall, 26.0% of CIN-1, 50.0% of CIN-2 and 70.6% of CIN-3 biopsies tested positive for HPV-6-11-16-18 infections.

CONCLUSION

Women with a given HPV type may often be co-infected or subsequently infected with other types which may lead to subsequent cervical lesions. This issue has been addressed in this study reporting data for the natural history of HPV-6-11-16 and -18 infections and is a relevant consideration in designing future studies to evaluate the incidence/risk of CIN following other type-specific HPV infections.

CHAPTER 6 Secondary prevention of cervical cancer

Cervical cancer continues to be the commonest cause of death among women in developing countries, largely due to the failure to initiate or sustain effective cytology-based screening programs. Experience from countries with successful screening programs indicates that target age and the extent of coverage of the target group are key indicators of success in reducing cervical cancer. Alternative methods for the secondary prevention of cervical cancer have been evaluated in numerous studies over the past 10 years in different countries. These include visual inspection with acetic acid and linking screening to treatment. Although longitudinal data are scanty, these alternative approaches have been shown to be feasible, acceptable, and effective in reducing cervical cancer.

Cervical cancer prevention for all the world's women: Genuine promise resides in skilled quality management rather than novel screening approaches

The debate over the best route for cervical cancer prevention in developing countries may be considered part of a larger debate over whether the global health community has become enamored with the promise of new approaches at the expense of delivering available preventives today. Pap screening, which is feasible anywhere cervical screening is appropriate, is the only intervention currently available for the prevention of cervical cancer in developing countries, and the Pap test will be an essential component of future novel preventive approaches. Cervical cancer vaccination, the long-term effectiveness of which is uncertain, will not eliminate screening requirements and is currently not affordable in developing countries. Root cause analyses, which may appropriately inform the best routes for improving health in developing countries, document that failures of cervical cancer prevention efforts are not attributable to factors specific to the Pap test but to lapses in programmatic quality management to which all screening tests are vulnerable. The genuine promise of cervical cancer prevention for all the world's women therefore resides in skilled quality management rather than novel screening approaches. We propose a global consensus policy by which Pap screening services will be provided in any setting where cervical screening is appropriate but unavailable, with consideration given to novel preventive approaches as they mature. Opportunity costs, borne by the underserved, are associated with prioritizing research on new approaches in any setting where established preventives are feasible but unavailable.

DNA ploidy compared with human papilloma virus testing (Hybrid Capture II) and conventional cervical cytology as a primary screening test for cervical high-grade lesions and cancer in 1555 patients with biopsy confirmation

BACKGROUND

Because 80% of cervical cancers arise in low-resource settings, many inexpensive strategies are being tested. In that spirit, the authors are testing large-scale genomic or DNA ploidy measurements as an inexpensive and semiautomated strategy.

METHODS

Patients entered either a screening or diagnostic study of several optical technologies: quantitative cytology, quantitative histopathology, and fluorescence and reflectance spectroscopy using a point probe, a multispectral digital colposcope, or a combination of the two. We calculated sensitivities, specificities, positive and negative predictive values, and their confidence interval testing conventional cytology, Hybrid Capture (HC) II testing, and DNA ploidy measured on the Feulgen-stained quantitative Pap smear.

RESULTS

The current investigation reports on 1555 patients for whom colposcopically directed biopsies were read 3 times by study pathologists. The final histopathologic diagnosis was high grade (cervical intraepithelial neoplasia [CIN] 2, CIN 3, carcinoma in situ [CIS], and cancer) in 16% of patients. Using high-grade squamous intraepithelial lesions (SILs) histopathology as the threshold and gold standard, the sensitivity and specificity, respectively, were: 0.47 and 0.96 for conventional cytology, 0.91 and 0.80 for HC II, and 0.59 and 0.93 for DNA ploidy. The positive and negative predictive values (PPV, NPV) for conventional cytology were 0.70 and 0.90, 0.46 and 0.98 for HC II, and 0.63 and 0.92 for DNA ploidy.

CONCLUSIONS

DNA ploidy shows comparable sensitivity, specificity, PPV, and NPV values to conventional cytology and HC II. Unlike conventional cytology, DNA ploidy is semiautomated and can be performed in less than 8 hours. Cost effectiveness studies are under way, but in the authors' laboratory DNA ploidy is inexpensive.

Estimating the cost of cervical cancer screening in five developing countries

BACKGROUND

Cost-effectiveness analyses (CEAs) can provide useful information to policymakers concerned with the broad allocation of resources as well as to local decision makers choosing between different options for reducing the burden from a single disease. For the latter, it is important to use country-specific data when possible and to represent cost differences between countries that might make one strategy more or less attractive than another strategy locally. As part of a CEA of cervical cancer screening in five developing countries, we supplemented limited primary cost data by developing other estimation techniques for direct medical and non-medical costs associated with alternative screening approaches using one of three initial screening tests: simple visual screening, HPV DNA testing, and cervical cytology. Here, we report estimation methods and results for three cost areas in which data were lacking.

METHODS

To supplement direct medical costs, including staff, supplies, and equipment depreciation using country-specific data, we used alternative techniques to quantify cervical cytology and HPV DNA laboratory sample processing costs. We used a detailed quantity and price approach whose face validity was compared to an adaptation of a US laboratory estimation methodology. This methodology was also used to project annual sample processing capacities for each laboratory type. The cost of sample transport from the clinic to the laboratory was estimated using spatial models. A plausible range of the cost of patient time spent seeking and receiving screening was estimated using only formal sector employment and wages as well as using both formal and informal sector participation and country-specific minimum wages. Data sources included primary data from country-specific studies, international databases, international prices, and expert opinion. Costs were standardized to year 2000 international dollars using inflation adjustment and purchasing power parity.

RESULTS

Cervical cytology laboratory processing costs were I$1.57-3.37 using the quantity and price method compared to I$1.58-3.02 from the face validation method. HPV DNA processing costs were I$6.07-6.59. Rural laboratory transport costs for cytology were I$0.12-0.64 and I$0.14-0.74 for HPV DNA laboratories. Under assumptions of lower resource efficiency, these estimates increased to I$0.42-0.83 and I$0.54-1.06. Estimates of the value of an hour of patient time using only formal sector participation were I$0.07-4.16, increasing to I$0.30-4.80 when informal and unpaid labor was also included. The value of patient time for traveling, waiting, and attending a screening visit was I$0.68-17.74. With the total cost of screening for cytology and HPV DNA testing ranging from I$4.85-40.54 and I$11.30-48.77 respectively, the cost of the laboratory transport, processing, and patient time accounted for 26-66% and 33-65% of the total costs. From a payer perspective, laboratory transport and processing accounted for 18-48% and 25-60% of total direct medical costs of I$4.11-19.96 and I$10.57-28.18 respectively.

CONCLUSION

Cost estimates of laboratory processing, sample transport, and patient time account for a significant proportion of total cervical cancer screening costs in five developing countries and provide important inputs for CEAs of alternative screening modalities.

Cervical cancer in the developing world

In developed countries, systematic screening programmes have reduced the morbidity and mortality resulting from cervical cancer. Cytological methods of screening have been the mainstay in these countries. Nevertheless, there is scant evidence that cytology-based screening has had any effect in reducing cervical cancer mortality in less-developed countries. In fact, the challenge in less-developed countries is surpassed by the complex array of problems that go far beyond the introduction of simplified technologies. Currently, there are two main issues on this subject: the assessment of simpler screening methods, and the evaluation of different strategies regarding which women to target and the screening interval. Achieving high rates of coverage and compliance of the target population through high-quality procedures has remained the most difficult goal to achieve. Nevertheless, it is believed that creativity, flexibility and well-focused use of resources can reduce the inequitable burden of cervical cancer borne by women in poor countries.

Systems analysis of real-world obstacles to successful cervical cancer prevention in developing countries

Papanicolaou screening is feasible anywhere that screening for cervical cancer, the leading cause of cancer-related death among women in developing countries, is appropriate. After documenting that the Vietnam War had contributed to the problem of cervical cancer in Vietnam, we participated in a grass roots effort to establish a nationwide cervical cancer prevention program in that country and performed root cause analyses of program deficiencies. We found that real-world obstacles to successful cervical cancer prevention in developing countries involve people far more than technology and that such obstacles can be appropriately managed through a systems approach focused on programmatic quality rather than through ideological commitments to technology. A focus on quality satisfies public health goals, whereas a focus on technology is compatible with market forces.

Introducing medical abortion within the primary health system: comparison with other health interventions and commodities

Over the years, a de-medicalisation strategy has been adopted for a range of public health interventions and commodities for the reduction of mortality, morbidity and population growth, including those for reproductive, neonatal and child health, communicable diseases, and trauma and emergency care, as a way of enhancing access to essential services. These experiences carry valuable lessons for de-medicalising and simplifying the provision of medical abortion. Like the combined oral pill and emergency contraception, which have become non-prescription drugs despite strident opposition, the abortion pill fundamentally alters the relationship between women and their health care providers. Measures for de-medicalising primary health services include adoption of simpler technology and service protocols, authorisation and training of less qualified providers, simplification or elimination of facility requirements, establishment of robust referral links to hospitals, increasing user control and self-medication, and simplifying arrangements for financing. By applying these measures, medical abortion can be widely provided as a primary health care service. To enable this, however, laws and policies must move beyond the surgical abortion paradigm, drugs must become reliably available at affordable cost, and women must have access to information that de-stigmatises abortion, enhances their options and aims to balance the power between them and their health care providers.

Worldwide burden of gynaecological cancer: the size of the problem

The estimation of cancer burden is valuable to set up priorities for disease control. The comprehensive global cancer statistics from the International Agency for Research on Cancer indicate that gynaecological cancers accounted for 19% of the 5.1 million estimated new cancer cases, 2.9 million cancer deaths and 13 million 5-year prevalent cancer cases among women in the world in 2002. Cervical cancer accounted for 493 000 new cases and 273 000 deaths; uterine body cancer for 199 000 new cases and 50 000 deaths; ovarian cancer for 204 000 new cases and 125 000 deaths; cancers of the vagina, vulva and choriocarcinoma together constituted 45 900 cases. More than 80% of the cervical cancer cases occurred in developing countries and two-thirds of corpus uteri cases occurred in the developed world. Political will and advocacy to invest in healthcare infrastructure and human resources to improve service delivery and accessibility are vital to reduce the current burden in low- and medium-resource countries.

Delivering cervical cancer prevention services in low-resource settings

The goals of any cervical cancer prevention program should be threefold: to achieve high coverage of the population at risk, to screen women with an accurate test as part of high-quality services, and to ensure that women with positive test results are properly managed. This article focuses on the experiences of the Alliance for Cervical Cancer Prevention (ACCP) in delivery of screening and treatment services as part of cervical cancer prevention projects in Africa, Latin America, and Asia. Research and experience show that cervical cancer can be prevented when strategies and services are well planned and well managed and when attention is paid to program monitoring and evaluation. Coordination of program components, reduction of the number of visits, improvement of service quality, and flexibility in how services are delivered are all essential features of an effective service.