(When I saw this headline, I was confused as I didn’t think cancer could be treated with a vaccine….as I read further I understood…them damn epidemiologists are pretty darn smart…cd)
Vaccine Prevents Most Cervical Cancer – New York Times
Vaccine Prevents Most Cervical Cancer
By DENISE GRADY
Published: October 7, 2005
An experimental vaccine has proved highly effective at preventing cervical cancer in a two-year study involving more than 12,000 women, researchers reported yesterday.
The vaccine works by making people immune to two types of a sexually transmitted virus that cause most cases of the disease. It is the first successful vaccine ever developed specifically to prevent cancer.
The vaccine, Gardasil, is made by Merck & Company, which plans to apply for approval to the Food and Drug Administration before the end of this year and, if the vaccine is approved, to market it in 2006.
If widely used, the vaccine could save many lives. Worldwide, there are about 500,000 new cases of cervical cancer a year, and 290,000 deaths. Most of the cases and most of the deaths occur in poorer countries where women do not have regular Pap tests, which can detect cancers or precancerous cells early enough for them to be cured. In the United States, where Pap tests are common, 10,400 new cases are expected in 2005, and 3,700 deaths.
“The potential, particularly in the undeveloped world, particularly if they can overcome the logistics and get the vaccine to those women, could be enormous,” said Dr. Deborah Saslow, director of breast and gynecological cancer at the American Cancer Society. The vaccine could prevent at least 70 percent of the deaths from cervical cancer, Dr. Saslow added.
But Dr. Allan Hildesheim, an epidemiologist at the National Cancer Institute, cautioned that even if women are vaccinated, they will still have to be screened regularly for cervical cancer because the vaccine does not prevent all cases of the disease.
“This is not a panacea,” Dr. Hildesheim said.
The vaccination will require three shots over six months. Merck has not said what it will cost.
The ideal time to vaccinate girls is before they become sexually active and risk being exposed to one of the cancer-causing viruses, said Dr. Eliav Barr, a research director at Merck. Once cancer develops, it is too late for the vaccine to help. The median age at which girls first have sex in the United States is 15.
It is not known yet how long the protection from the vaccine will last, or whether booster shots will be necessary, Dr. Barr said.
The vaccine works against viruses that belong to a group called human papillomaviruses, or HPV. Nearly every case of cervical cancer is caused by HPV. The viruses are sexually transmitted, extremely common and almost impossible to avoid. At least half the adults in the United States have been infected.
More than 30 types of HPV infect the human genital area. Only some types cause cancer; others cause genital warts. A type known as HPV-16 causes 50 percent of cervical cancers, and HPV-18 causes 20 percent. Other types cause the rest. But even the cancer-causing types are harmless in most people because their immune systems fight them off.
The virus persists in some women, however, causing abnormal growths on the cervix. Most of the growths go away, but some turn cancerous.
Gardasil protects against HPV 16 and 18, which together cause 70 percent of cervical cancers. It is also designed to prevent infection with two other virus types, 6 and 11, which cause 90 percent of cases of genital warts. The four virus types can cause non-cancerous cervical growths that lead to nerve-racking false alarms on Pap tests, and the vaccine is expected to spare many women the abnormal test results.
Merck scientists were scheduled to present the results of the two-year study today at an infectious disease conference in San Francisco.
Their test group included more than 12,000 women, ages 16 to 26, from 13 countries. Half got Gardasil and half placebos.
Among the women who received all three doses of vaccine and did not have HPV infection when they started the study, the researchers found no precancerous cells or early cervical cancers associated with HPV 16 or 18. But among those who got placebos, there were 21 cases.
The findings mean the vaccine was 100 percent effective at preventing the cancers caused by types 16 and 18. But some women in the vaccinated group did develop precancerous cells caused by other HPV types; the company did not disclose how many.
The vaccine is made up of proteins that are normally found on the outer shell of HPV. The proteins, called viruslike particles, are produced by yeasts that have been spliced with viral genes. They provoke a strong immune response that can then prevent infection.
Although Merck will first seek permission to vaccinate girls and women, the company plans eventually to seek approval to use Gardasil in boys and men as well. The company hopes the vaccine will appeal to men because it may prevent genital warts, which can turn into large, ugly growths on the penis.
Vaccinating men might protect their sexual partners as well, including not just women but men who have sex with men, a group at risk for anal cancer caused by HPV. However, Merck has not disclosed any data on whether the vaccine works in men.
Another drug maker, GlaxoSmithKline, is also working on a cervical cancer vaccine, one that does not include wart protection. The company did not respond to several telephone requests for information on the status of its vaccine.