Independent Perspective News

By DENISE GRADY

Scientists are reporting today that they have created the first vaccine that appears able to prevent cervical cancer. The vaccine works by making people immune to a sexually transmitted virus that causes many cases of the disease. The vaccine is experimental and will not be available to the public for several years.

A successful vaccine could sharply reduce rates of cervical cancer, which affects 470,000 women a year worldwide and kills 225,000. In the United States, there are 13,000 cases a year and 4,100 deaths.

In a study of 2,392 young women, half of them vaccinated and half given placebo shots, the vaccine was 100 percent effective. Followed for 17 to 27 months, no vaccinated women developed infections or precancerous growths from the virus, whereas 41 nonvaccinated women did become infected, including 9 with precancerous cervical growths. A report on the study is being published today in The New England Journal of Medicine.

"These are tremendous results," said Dr. Laura A. Koutsky of the University of Washington in Seattle, director of the study, which was carried out by researchers from 16 universities and Merck Research Laboratories, a unit of Merck & Company. Merck made the vaccine and paid for the research. "It's very encouraging that there will be a vaccine to prevent invasive cervical cancer," Dr. Koutsky said.

An expert not connected with the study, Dr. Carol L. Brown, a gynecologic cancer surgeon at Memorial Sloan-Kettering Cancer Center in New York, called the study "highly, highly significant and very exciting."

"This has the potential if it pans out to be a really effective way of preventing cervical cancer," Dr. Brown said. The vaccine described today was made to test whether people could be made immune to only one type of the cancer-causing virus, which causes 50 percent of cervical cancers. That vaccine is not the one that Merck hopes to market, company officials said. Merck is already testing a new version designed to work against multiple virus types, preventing 70 percent of cervical cancers, but it will not be ready for several years, a company scientist said.

The vaccine, given in three shots over six months, can be used to prevent cervical cancer but will not be able to treat it. As a preventive, it will be most successful if it is given to girls and young women before they become sexually active. Researchers cautioned that the vaccine would not do away with the need for Pap tests to screen for cervical cancer, because it cannot prevent every virus that can cause the disease.

Dr. Allan Hildesheim, a senior investigator at the National Cancer Institute, called Merck's results extremely promising, but, he said, larger and longer-term trials were needed to make sure the vaccine was safe and effective, especially since it is intended for large numbers of young, healthy people. He said researchers at the cancer institute were also developing a cervical cancer vaccine. So is GlaxoSmithKline, a spokeswoman for the company said.

Most deaths from cervical cancer occur in developing countries where women do not have regular Pap tests, which can detect abnormal growths early so they can be removed before they turn cancerous. Vaccination is less complicated than cancer-screening programs and may be a more practical option in many parts of the world.

"For individuals in countries with no screening, vaccination is a lifesaver," said Dr. Kathrin U. Jansen, senior director of microbial vaccine research at Merck.

In the United States, where 50 million to 60 million Pap tests are done every year, a great benefit of a vaccine would be a drop in the number of women who, because of the virus, have abnormal Pap tests and then need repeated examinations and tests to look for cancer. Most of the abnormalities will not turn cancerous, but it is hard to predict which ones will, so all must be monitored. Some women have surgery they may not need. By preventing the infections and abnormal growths, a vaccine could spare close to a million women a year the worry, expense and unpleasant procedures. Cost savings could be in the billions.

In an editorial in The New England Journal of Medicine, titled "The Beginning of the End for Cervical Cancer?" Dr. Christopher P. Crum wrote that if an effective vaccine became available, "the captives of our current system — both patients and their caregivers — may be set free." Dr. Crum is director of women's and perinatal pathology at Brigham and Women's Hospital in Boston.

There is now only one widely used vaccine that prevents cancer: the vaccination against the hepatitis B virus. In parts of Africa and Asia, chronic infection with that virus is a major cause of liver cancer, and, Dr. Crum noted, rates of both the infection and the cancer have dropped markedly in areas with vaccination programs.

A few other cancers, including certain types of leukemia and lymphoma, have been linked to viruses, but vaccines for them do not exist.

Dr. Koutsky said it had been suggested that many parents, loath to acknowledge that their teenage daughters could be sexually active, would refuse the vaccine.