The World Health Organization (WHO) and European Organization on Genital Infection and Neoplasia (EUROGIN) have released a joint report entitled, "Cervical Cancer Control." The report, a summary of 62 scientific papers presented at a WHO/EUROGIN meeting held in Geneva in 1996, discusses the various aspects of cervical cancer control and contains recommendations for management of cervical neoplasia, development of vaccines against human papillomavirus (HPV), screening programs and strategies, including Pap smears and new technologies in cervical screening.
Since 1943, when Papanicolaou and Traut proposed a new technique-the Pap smear test-to detect precursors of cervical cancer in women, cytologic screening has been one of the most successful public health measures introduced for the prevention of cancer. Mass screening programs in which women have cervical smear tests at least once every 3 to 5 years, have proven effective in reducing cervical cancer mortality and morbidity rates. In British Columbia (Canada) and Finland, for example, organized screening has reduced mortality rates by up to 70%.
Cervical Cancer Screening Failures
In spite of all these achievements, the reality of the situation worldwide is discouraging. Close to half a million women develop cervical cancer annually and more than 50% of those women die. Seventy-five percent of all cases of cervical cancer occur in the developing world, where, because of financial constraints, mass screening programs are still wishful thinking.
Even in many developed countries, the decline of the disease in the past decade has been insignificant, and the impact of cytologic screening has been far less than expected. In fact, there seems to be a substantial number of cases of invasive cervical cancer occurring in patients who are regularly screened, particularly young women.
According to the report, factors that determine the success of cervical cancer screening are:
- coverage of the population at risk through organized, "voluntary" screening
- quality assurance in the collection and interpretation of cervical smears.
Why cervical cancer sometimes cannot be detected through cytologic screening may be attributed to the large intervals (more than 5 years) between tests and the high number of false-negative results (10% to 30%).
False Negatives
Two principal causes for the false negatives are the poor quality of samples and inappropriate interpretation of results. These limitations can be overcome through improved sampling and the introduction of automated devices that can detect 30% to 50% more false negatives than humans can. It is essential that medical and laboratory personnel involved at all steps of cytologic testing be adequately trained, according to the report.
"New technologies, like automation and monolayer systems should optimize cervical cancer screening, reduce false-negative rates, and improve quality control," comments Dr. Joseph Monsongego of France, EUROGIN's Executive Secretary and gynecologist in the Institut Alfred Fournier in Paris. "These new technologies could have an enormous impact on the effectiveness of cervical cancer screening. That is why the development of comparative trials, including cost-benefit evaluation, should be considered in the future."
The recognition that HPV infection is a central cause of cervical cancer by the International Agency for Research on Cancer (IARC) and WHO has paved the way for the design of strategies for primary prevention, by immunization, and for secondary prevention, using HPV DNA testing as a screening tool. This new molecular technique can be used after cytologic screening detects minor cervical smear abnormalities. Colposcopy can determine the nature and extent of cervical lesions in women with abnormal smears by taking biopsies.
"The time has come to improve strategies for cervical cancer screening. In order for cytologic screening programs to be cost-effective, they should cover most of the at-risk female population and be initiated only when their quality at all levels, including sampling and interpretation of results, has been ensured," said Dr. Mark Tsechkovski, Director of the WHO Division of Non-communicable Diseases in Geneva.
For further information, contact Igor Rozov, Health Communications and Public Relations, WHO, Geneva; tel, 4122-791-25-32, fax, 4122-791-48-58.
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