TOPICS > Health

Cervical Cancer Vaccine

November 21, 2002 at 12:00 AM EDT


GWEN IFILL: The new study out in today’s edition of the New England Journal of Medicine reports on a major advance in preventing cervical cancer, a disease that strikes 450,000 women worldwide each year, killing about half. It’s a cervical cancer vaccine that was 100% effective in its first big clinical trial.

Here to help us walk through the study and what it means for treatment and prevention, is Dr. Christopher Crum, director of Women’s and Perinatal Pathology at Brigham and Women’s Hospital in Boston. He wrote the editorial that accompanies the study in the New England Journal.

Welcome, Dr. Crum.

DR. CHRISTOPHER CRUM: Thank you. Well, for background —

GWEN IFILL: What is cervical cancer? What is it and why are we concerned about it?

DR. CHRISTOPHER CRUM: Well, for background, virtually all cervical cancers are associated with sexually transmitted papaloma viruses. Most of the women who are looking at this program have probably be exposed to one or more of these viruses in their lifetime. However, the vast majority will regress on their own. In a percentage of these infections, a pre-cancerous disease will develop in the cervix and cause an abnormal pap smear. In many of these cases, they’re successfully treated by various methods of ablation. In a small number of cases, cancer will develop

GWEN IFILL: What is ablation?

DR. CHRISTOPHER CRUM: Removal by some minor surgical procedure.

GWEN IFILL: This is the HPV virus that you’re talking about when you talk about this, right?

DR. CHRISTOPHER CRUM: That is correct.

GWEN IFILL: And this is fairly common in most women?

DR. CHRISTOPHER CRUM: It’s a very common virus that we see very frequently. I think you can expect a very high percentage of young women to encounter the virus during their reproductive life. However, only a certain small percentage actually develops significant pre-cancerous changes.

GWEN IFILL: Is cervical cancer, does it have a high mortality rate?

DR. CHRISTOPHER CRUM: Well, if it’s not detected until it’s very late in its stage, it may. If it’s detected early, it’s very easy to treat and prevent cancer, or prevent death due to cancer. Now, the MERCK-sponsored study took a look at one of the papaloma viruses that’s very common and commonly associated with cancer, which is type 16. And what they did was they vaccinated women against this papaloma virus and then observed them to see whether they developed a virus infection or developed a pre-cancer that could be attributed to that particular virus. And as the vaccine study showed, they were 100% successful at preventing both the infection and the pre-cancer. And because…

GWEN IFILL: I’m sorry. We’re talking about — the study was directed at young women, not any woman could walk in tomorrow and get this vaccine and say, “aha, I never have to worry about cervical cancer,” right?

DR. CHRISTOPHER CRUM: That is correct. They actually targeted women who had never been exposed to this particular papaloma virus.

GWEN IFILL: Which means they were not sexually active because this is a sexually transmitted virus.

DR. CHRISTOPHER CRUM: Well, they may have been sexually active, but they had not been expose today this particular virus. That was one of the criteria for entering the study.

GWEN IFILL: So how long would this last, then? How long would the vaccine be effective?

DR. CHRISTOPHER CRUM: Well, it’s a good question. Certainly the immune response to that vaccine generated was very powerful and much higher than we see in natural infection. So hopefully the vaccine may generate an immune response that’ll last some time.

GWEN IFILL: We’re talking about young women involved in this study. Would there be any reason for men to take that vaccine?

DR. CHRISTOPHER CRUM: Well, it certainly would not be a bad idea. Certainly could you argue that if you vaccinated men, you might protect women from infection.

GWEN IFILL: So in the end… because men could transmit this infection, that them taking the vaccine would have some effect is what you’re suggesting?

DR. CHRISTOPHER CRUM: Yes, it could affect both men and women. And the study by CAT scan, the ability to detect even small amounts of virus in the genital tracts of women was significantly reduced by this vaccine indicate flag they would be very unlikely to transmit the virus either.

GWEN IFILL: In your opinion, how conclusive is this study? Are we saying that we are on the verge now of wiping out cervical cancer?

DR. CHRISTOPHER CRUM: Well, the vast majority of cervical cancers are preceded by infection and preceded by a pre-cancer. And since these are the two earliest phases in the pathogenesis of the cancer, if you were 100% effective at removing those particular phases, I would think you have a very strong chance of eradicating cancer with a vaccine of that sort.

GWEN IFILL: Now, right now, the way it stands, without this vaccine, the best way to detect cervical cancer is in a pap smear. Would this vaccine, the existence of a successful round of this vaccine for the general public, would it eliminate the need for pap smears?

DR. CHRISTOPHER CRUM: Well, as you can imagine, it would take many years to be absolutely certain these vaccines prevented cancer because it takes nearly one or two decades before cancer even develops in its natural state. So one would expect that women would continue to be screened with pap smears just to be safe, but the expectation is that they would not develop cancer, at least the cancer associated with those viruses that were used in the vaccines.

GWEN IFILL: Is this kind of treatment applicable to other cancers? Is there any evidence that vaccines have been used or could be used to prevent other kinds of cancer?

DR. CHRISTOPHER CRUM: Well, certainly other vaccines are being tried in cancers, but not with this kind of success. The success you see in this particular study is due to the fact that this vaccine is targeting a specific virus that’s associated with cervical cancer. And thus preventing the virus, by definition, should prevent the cancer. Many other cancers in the body are not associated with viruses, and the vaccine logistics are much more complicated.

GWEN IFILL: If this study continues in a wider way, when could people expect to see this kind of vaccine become available?

DR. CHRISTOPHER CRUM: It’s difficult to say, but certainly some of the representatives of MERCK have suggested in a few years it might come on the market.

GWEN IFILL: And would it be expensive? And would the government be expected to try to cover some of this or to allow for insurance companies to cover the cost?

DR. CHRISTOPHER CRUM: That’s a very difficult question to answer. In terms of the insurance companies, however, if you can prevent these infections, you certainly would prevent many of the expensive technologies that are required to manage women with abnormal pap smears, so one would hope that the cost benefit of a vaccine would be quite high.

GWEN IFILL: But because we’re talking about vaccinating teenagers whose parents would be making the decision about their medical health, would you have the additional hurdle to get over of trying to convince parents that they’re basically… that their daughters should be vaccinated for something which assumes some sort of sexual activity?

DR. CHRISTOPHER CRUM: Well, it’s a good question, but I would hope that most parents who have children would consider — very strongly consider letting them be vaccinated for a virus that causes cancer. I would think that might override the concern about the fact that they may become sexually active too early.

GWEN IFILL: There was a related study today which also showed in advances being made for cures for herpes or at least potential cure for herpes.

DR. CHRISTOPHER CRUM: This was another study that was done. It did not get quite the press, you might say that the papaloma vaccine received, partly because herpes viruses are not associated with cancer, at least this particular virus. And the vaccine was not 100% successful at preventing infection. But not unlike the papaloma virus, it was quite successful in about 70% of women, and it was most successful in those young women who had never been exposed to herpes viruses.

GWEN IFILL: Okay, well, thank you very much for helping us with this, Dr. Christopher Crum.