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Worldwide cervical cancer prevention strategies
[Reproduced from the Reproductive Health Outlook (RHO) Website (http://www.rho.org), 2000.]
Bishop, A. et al., Cervical cancer: evolving prevention strategies for developing countries, Reproductive Health Matters 6:60-71 (November 1995) This article makes a strong case for rational, public health approaches to the prevention and treatment of cervical cancer, focusing on practical strategies that can be used in developing countries. The authors note that scarce resources, limited infrastructure, and competing health priorities have prevented most developing-country health systems from implementing successful programs. Three approaches to cervical cancer screening are suggested for programs with limited resources:
- 1. screening women aged 30-35 or older;
2. screening women relatively infrequently; and
3. considering alternate approaches to conventional screening techniques.
For women identified as needing treatment, the authors discuss outpatient approaches, such as cryotherapy and loop electrosurgical excision procedure (LEEP), that can effectively treat most precancerous lesions and reduce the number of clinic visits. The authors recommend coordinating efforts to achieve broader screening and treatment coverage, and they note that introducing alternate approaches requires policy changes, for which community input is essential.
Fahey, MT et al., Meta-analysis of Pap test accuracy, American Journal of Epidemiology 141:680-689 (1995) This meta-analysis examined 62 studies published by August 1992 that compared Papanicolau (Pap) test results with histology. Data from 59 of the studies were used to assess the accuracy of the Pap test. Estimates of Pap smear sensitivity ranged from 11% to 99% and estimates of specificity ranged from 14% to 97%. The authors found that a specificity in the 90%-95% range on a Pap test corresponds to a sensitivity in the 20%-35% range. While many studies had methodological weaknesses, the authors concluded that an increase in sensitivity almost always corresponded to a decrease in specificity or vice versa and that the Pap cannot achieve concurrently high sensitivity and specificity. They recommended that future studies follow methodologic standards for diagnostic test evaluation more closely.
Fahs, MC et al., Cost-effective policies for cervical cancer screening: An international review, Pharmacoeconomics 3: 211-230 (March 1996) This international review of the cervical cancer literature focuses on studies that address the cost-effectiveness of cervical cancer screening. The authors conclude that centrally organized screening programs implemented by the public sector are the most cost-effective type of program. Many programs are not effective (and have limited impact) due to over screening of younger, affluent, lower-risk women and under screening of older, less affluent, and minority women (for example with opportunistic screening and screening at the discretion of individual health care practitioners). The authors also conclude that it is more cost-effective to begin screening of women between the ages of 25 and 35. The appropriate cost-effective age to end screening is less clear; once an older woman has had several negative Paps, screening is less efficient and can be discontinued. The authors found that the interval of screening with the best balance between cost and life years saved was between 3 and 5 years. However, when repeat screening is not feasible, even one test per lifetime can significantly reduce mortality of a population. Efforts to reach unscreened women are particularly important as this population is typically at higher risk of developing cervical cancer. The authors noted three factors that can heavily impact the cost-effectiveness of a screening program: proportion of women screened by the program, quality of the Pap smear, and the cost of the Pap smear. Finally, the review discusses different cost models and analyses for evaluating cervical cancer screening and suggests the need for models that incorporate total costs and benefits of cervical cancer screening to society.
Ponten, J et al., Strategies for global control of cervical cancer, International Journal of Cancer 60:126 (1995) This extensive review summarizes data from around the world on cervical cancer. Topics addressed include the tumor biology and natural history of cervical cancer, etiology of the disease (including impact of HPV), strategies for reducing mortality without screening (including focusing on treatment of early stage disease), and cytological screening. The authors concluded that the natural history and disease patterns of cervical cancer are similar throughout the world. They argued that HPV testing as a strategy for cervical cancer control remains experimental, and that providing treatment for early stage disease where feasible can help reduce mortality. They discussed the challenges of ensuring maximum coverage with cytological screening without wasting resources on frequent testing of women at lower risk.
