Almost two decades ago, a doctor named Surendra S. Shastri was put in charge of preventative oncology at Tata Memorial Hospital in Mumbai, India. One of his biggest jobs: to figure out how to cut the toll from cervical cancer, which kills 200,000 women a year in the developing world but is rare in developed countries.
In the United States, that death toll is just 4,000, the result of the most successful story of early detection preventing cancer death. Unlike most other cancers, cervical cancer starts as a pre-cancerous lesion that accumulates mutations. The Pap smear, a technique invented in the 1920s by George Papanicolau, a Greek pathologist at Cornell University, involves a doctor taking cells from the lining of the cervix and sending them to a lab to be analyzed under a microscope. Annual pap smears mean most cases of cervical cancer that would happen in the U.S. are caught before they become deadly tumors. In India, which has the world's worst cervical cancer burden, the introduction of annual Pap smears for all women seems impossible.
“We don't have the kind of laboratories or the kind of trained manpower needed for having a Pap smear. The Pap smear has succeeded in the countries where it has because of good quality control and frequency of screening,” Shastri says. He needed something far cheaper. The idea that he and others hit upon was to steal a step from from the procedure that follows a suspicious Pap smear. Doctors pour acetic acid – basically a sterile vinegar solution – onto the cervix and look at it under a magnifier. Cancer and precancer cells have less of the gooey cytoplasm than healthy cervix, and the acetic acid makes them actually turn white after just a minute. The normal cells remain a healthy pink.
Shastri skipped the magnifier and the doctor, and decided to train the same health care workers who give immunizations and other basic preventative measures to apply an acetic acid solution in the field. In 1998, he obtained funding from the National Cancer Institute, one of the U.S. National Institutes of Health, to conduct a fifteen-year clinical trial comparing using the vinegar screen once every two years to not screening in 150,000 women. The results are being presented today here at the annual meeting of the American Society for Clinical Oncology. The vinegar test reduced the rate of cervical cancer death from 16.2 women per 100,000 to 11.1 women per 100,000, a 31% reduction.
“It's amazing,” says Carol Aghajanian, chief of gynecologic oncology at
Shastri and his co-authors estimate that in India alone, the introduction of acetic acid screening could prevent 22,000 cervical cancer deaths annually. If it could be instituted across the developing world, that would save 73,000 lives.
Based on those results, the national government in India and the state government of Maharashtra, the state of which Mumbai is the capital, are instituting screening programs for all women. But translating this procedure from Tata Memorial Hospital to the rest of India or from India to the rest of the world does pose challenges.
Ted Trimble, the Director of the Center for Global Health at the NCI, notes that the health care workers did more than just use tests. They made innovative use of new technology – using digital cameras to record exams so they could be reviewed later and geomapping of the slums of Mumbai so women could be found – and of super-organized records. More than that, he says, the workers did a great job of making sure women who were screened as potentially having cancer did get to Tata Memorial for their exams. Will other hospitals in other countries be as diligent outside of a controlled clinical trial? It's impossible to know.
Still, this is a striking example of how a low-tech, low-cost intervention can sometimes take the place of a more high-tech innovation. In 2009, Shastri co-authored a paper in the New England Journal of Medicine showing that a single round of acetic acid screening was about the same as a single pap smear for detecting cervical cancer, but neither were as good as a newer invention, which tests for the viral DNA of the strains of the human papilloma virus that are the main cause of cervical cancer.
But the viral DNA test is expensive. Even in the U.S., it is so costly that it has not replaced Pap smears. The Bill & Melinda Gates Foundation has partnered with
The Gates Foundation still says that the new test should cost about $5, and that it has received regulatory approval from the European Union and been granted marketing authorization in many emerging markets, including India. But approval from the World Health Organization is still pending, and that will be necessary to allow agencies of the United Nations to procure the test.
Shastri says that even if the test becomes available, he is likely to use it only as a second step after the acetic acid screen. The current cost of screening one woman is about 30 Indian rupees, about half a U.S. dollar. Even if the cost of HPV viral testing can drop to $2, it will still best be used to make sure that cancer is detected in women whose cervixes show white areas after being exposed to acetic acid.
Other methods are also being used to help to reduce the number of cervical cancer deaths, too. Last month, Merck and GlaxoSmithKline dropped the prices of the two vaccines against HPV, Gardasil and Cervarix, to $4.50 and $4.60 per dose for use in the developing world. That's less than one-twentieth the price in the developed world.
There is also some good news on the treatment front: researchers at the ASCO meeting announced that Roche's Avastin can extend the life of an average woman with late-stage cervical cancer by four months to 17 months. It is not yet clear what can be done to get Avastin, which costs tens of thousands per year, available to rural women in the developing world.
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