Sticking it to Cancer
A new vaccine, amazingly, may rid the world of cervical cancer, while doctors aim other needles at more killer tumors
The vaccine looks like HPV, but it isn't. It's just an empty shell, made from the protein in the virus's outer coat. But that surface similarity is enough to provoke an immune response.
In fact, three injections of the vaccine, spread over six months, prompt the body to produce antibodies against these HPV types at levels that are hundreds of times as high as normal. Follow-up studies so far show that people maintain these heightened levels for at least 3
Long-lasting. Cervarix, the rival vaccine from Glaxo, is made in a similar way and shows very similar results. The differences: It vaccinates against types 16 and 18 only, and it contains a novel chemical to boost vaccine longevity, perhaps beyond what Gardasil is capable of. "We found that you get the strongest antibody response from kids ages 10 to 14, about twice as strong as older teens," says Gary Dubin, the virologist who heads Glaxo's HPV vaccine program. "So you vaccinate at a young age for the powerful response, but you need it to last." If it doesn't, kids will be at risk as they mature and start to have more sexual contacts. Dubin's group has shown that the strong response extends for at least four years and might last for a decade.
Helen Wright, age 14, of North Augusta, S.C., is taking part in some of these tests and would be grateful for some protection. "At first I was like 'I'm so scared' when I found out about HPV. But then I thought if I'm taking these shots, I might not catch it when I get older."
But nobody knows for sure. "Figuring out the duration of protection is going to be key," says Koutsky. For one thing, it will indicate when vaccinated people will need booster shots. So drug companies and researchers are following a group of people who were vaccinated several years ago, waiting and watching for signs of infection and disease. "Until we know about that, Pap smears are going to continue to be important for women," says Dartmouth's Harper. "Cancer prevention, in the future, is going to require screening as well as vaccines."
Prevention isn't the only goal of vaccines, however. For other cancers, they may work as treatments, like cancer-killing drugs. Prostate cancer, which will kill about 27,000 men in the United States this year, is one target. "I never felt sick, not once," says Harry Petersik, who had prostate surgery 12 years ago because a high prostate-specific antigen test led to the discovery of a tumor. Petersik, a 64-year-old electrician who lives near Edmonton in Alberta, Canada, thought he was out of the woods. But over the years his PSA levels kept climbing, indicating the cancer was back. Other treatments failed. By the start of 2005, the cancer had spread through his lymph system. And he had tumors in his back and shoulders.
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