Work on New Cervical Cancer Vaccine Continues

MARGARET WARNER: The first major study of an experimental vaccine for cervical cancer has shown dramatic results. The study on 12,000 women showed the vaccine, called Gardasil, to be 100 percent effective in blocking two common strains of the virus responsible for the sexually transmitted disease. About 10,000 American women contract cervical cancer annually and about 3,700 die from it each year.

Worldwide, cervical cancer is a much greater problem, causing more than a quarter of a million deaths per year. That makes it the second most lethal cancer among women. The manufacturer, Merck, which sponsored the study, said it intends to apply for FDA approval late this year, and it hopes to begin marketing the vaccine next year.

Dr. Garner, welcome. First of all, what is the significance of this study, in your view?

DR. ELIZABETH GARNER: I think this is hugely significant. You know, as you said, cervical cancer is a significant problem for women worldwide. And whereas women in this country don't see it as much around the world many, many women die each year. So the potential for a vaccine that could actually prevent this disease is truly huge.

MARGARET WARNER: So how does the vaccine work, how does it prevent the disease?

DR. ELIZABETH GARNER: So the idea is that if you give women a vaccine-like particle, something that looks just like the virus itself to the immune system, you can cause the immune system to have a response, as if the woman was infected with HPV.

And so women were administered this virus-like particle and in the study half the women got the particle and half of the women didn't. And the ones who received the particle actually had immune responses to HPV, or Human Papilloma Virus, which is the virus that causes the disease, and that helps lead to prevention of the changes that HPV causes.

DR. ELIZABETH GARNER: It's extremely common. Probably up to 20 million Americans at any one time are infected with HPV. It doesn't really have symptoms, and so most people don't know that they have it. And likely up to 50 percent of people are exposed to HPV and are infected with HPV transiently at some point during their lifetime, so it's extremely common.

MARGARET WARNER: Now explain why cervical cancer is so much more deadly elsewhere than it is in the United States.

DR. ELIZABETH GARNER: Well, we're fortunate in this country and in other developing countries around the world to have had the Pap smear, which since around the 1970s has tremendously decreased the incidence of cervical cancer.

Around the rest of the world and in developing countries, unfortunately, Pap smear screening programs really are essentially nonexistent. And so the ability to detect the early changes that occur in the cervix from Human Papilloma Virus has been essentially lacking.

MARGARET WARNER: And then what is the treatment, for instance, here in the United States if a woman gets a positive pap test for cervical cancer, what is the treatment?

DR. ELIZABETH GARNER: It depends on the stage of the disease. But fortunately, in this country, most women who are infected with HPV do not get cervical cancer because there are early changes or pre-cancerous changes, as we call them, dysplasia, that take place in the cervix on its way to becoming cancer, and most of the time at least in the United States we're able to detect those changes before it actually becomes cancer.

For women who actually do develop cancer -- and even some women who do get pap smears do get cervical cancers -- but in most situations again they are early, where surgery most of the time will be curative. And it's not in the more advanced stages women need to get radiation and chemotherapy.

DR. ELIZABETH GARNER: That's a little unclear, I think, still. You know, whether it's going to be most effective to give it to adolescents or children at an even younger age I think is yet to be determined. There certainly will be issues in terms, you know, of the durability of the protective response. Acceptability among parents I think is going to be an issue.

So I think you know a lot of things that have yet to be figured out in terms of decided who the best population is. The key is clearly to get it to women and perhaps eventually, or I should say girls, and perhaps boys before they're exposed, because this is, as we call it, a prophylactic vaccine, not one that actually treats the changes that are already there in the cervix.

MARGARET WARNER: So, in other words, they have to be given this before they are sexually active and it really doesn't do any good once you've even got the virus in you?

DR. ELIZABETH GARNER: Correct.

MARGARET WARNER: Would it eliminate the need for pap tests?

DR. ELIZABETH GARNER: I think that's also yet to be determined. You know, I think every woman would certainly hope that never to have another pap smear ever, but that still has yet to be seen. I think that until we're comfortable with the protective ability of this vaccine, it's -- I think the pap smear is still going to have a place.

Remember that the vaccine only protects against the two major forms of Human Papilloma Virus that cause cervical cancer. They cause probably 70 percent of cervical cancer, so you've got, you know, 30 percent still of cervical cancers that really are yet to be covered by a vaccine.

So I do think the Pap smear is going to around, unfortunately, for a little while.

DR. ELIZABETH GARNER: Most definitely. Cervical cancer is not the only cancer that's caused by Human Papilloma Virus. Certainly vaginal cancers and vulvar cancers are also caused by HPV. Additionally, in men certainly penile cancers are caused by HPV; there are some oral cancers that seem to be related, so it certainly has the potential to prevent all of those cancers.

MARGARET WARNER: And then from a research perspective, does the fact that now finally a vaccine has been developed against a specific cancer, does that suggest a pathway for other kinds of vaccines against other cancers?

DR. ELIZABETH GARNER: Most definitely. I think that, you know, it's yet to be seen but perhaps there are more cancers that are commonly known to us that may actually turn out to have a viral cause in the end. Certainly there are ones that are already known, nasopharyngeal cancer, for instance, certain gastric cancers are known to be viral related, liver cancer with the Hepatitis B virus.

So certainly I think that, you know, with this knowledge now that it's possible to accomplish protection against a cancer that's caused by a virus, there definitely is going to be much more research going into that area.

MARGARET WARNER: Dr. Elizabeth Garner, thanks so much.

DR. ELIZABETH GARNER: It's a pleasure.