An inexpensive, easy test that changes the color of precancerous tissue could be used to screen women for cervical cancer and its precursors in geographic areas where Pap smears may not be available, according to a study of African women by researchers at Johns Hopkins and the University of Zimbabwe.
Results of the study, published in the March 13 issue of the British journal The Lancet, showed that nurse-midwives who wiped a patient's cervix with acetic acid (vinegar) and then visually inspected the area accurately detected more than 75 percent of potential cancers among the study participants. Tissue harboring precancerous lesions turns white when exposed to vinegar. The test identified almost twice as many cases of disease as did Pap smears.
A simple screening test such as this is urgently needed, the authors say, because only 5 percent of women in developing countries are routinely screened for cervical cancer compared to up to 70 percent in industrialized nations. Cervical cancer--a sexually transmitted disease caused by the human papilloma virus--is the leading cause of female cancer deaths in parts of Africa, Asia and Latin America, killing 200,000 women each year.
"In most developing world countries, cervical cancer screening programs are small-scale or nonexistent," says Paul D. Blumenthal, an author of the paper and an associate professor of gynecology and obstetrics at Hopkins. "Even in countries where Pap smear-based screening is available, it is often done only in urban settings or in the private sector, which serves a relatively small proportion of the female population.
"This technique easily could be used by health care workers in areas with limited resources. The test is safe, affordable and effective and can help health care workers make an on-the-spot decision as to whether the patient may need further attention, including treatment--an important factor in regions where women may live far from medical facilities and cannot be easily followed once they leave," Blumenthal says.
During the first phase of the two-part study, nurse-midwives screened 8,731 African women for cervical cancer at 15 primary care clinics in Zimbabwe using both the vinegar/visual inspection method and Pap smears. The women ranged in age from 25 to 55 and were not pregnant. Although all were sexually active, fewer than 15 percent had ever been screened for cervical cancer. Colposcopy (high-powered magnification) and, when necessary, biopsy were used to confirm abnormal results or to verify the few women controls who tested negative.
In the second phase, 2,144 women received the visual inspection, a Pap smear and the reference test in the same day. In this phase, visual inspection correctly identified about 77 percent of the 207 serious precancerous or cancerous cases in this group. Visual inspection yielded a number of false positives, but researchers say improved training may reduce this problem in the future.
The study was supported by JHPIEGO, an affiliate of the university committed to international reproductive health interventions in areas with limited resources, with funding from the United States Agency for International Development. Other authors from Hopkins and JHPIEGO were L. Gaffikin, J. McGrath and H. Sanghvi.