College students know that having unprotected sex can lead to all sorts of undesirable consequences such as pregnancy and sexually transmitted diseases. But for a small number of women, it can also lead to cervical cancer. This goes against everything we are taught about cancer — that it is a malignant disease with no cure — but cervical cancer is different in this respect.
Almost every case of cervical cancer is caused by a long-term infection with one of 10 common strains of human papilloma virus, or HPV. Of these cases, half are caused by the HPV-16 strain and another 20 percent are caused by the HPV-18 strain, according to the National Cancer Institute.
A disease that causes warts on the hands, feet, mouth and genitals, HPV is the most common STD and is difficult to avoid for those who are sexually active. In fact, 75 percent of women and men contract HPV at one point in their lives, but in most cases, the infection will go away without causing a problem. For a small number of women that contract persistent infections, however, there is a high danger of developing cervical cancer, because a chronic infection with HPV is almost always known to preceed the development of this disease.
Cervical cancer is the second most common cancer in women. Each year, 470,000 women are diagnosed with cervical cancer worldwide. Approximately 80 percent of these cases occur in developing countries, and about half of these women will die from the disease. The medical advances in treating cervical cancer have given women in developed countries a far greater chance of surviving. This year in the United States, about 15,000 women will learn that they have cervical cancer, and more than 4,000 women will die because of it.
But there is new hope for women at risk of developing this cancer: a vaccine for HPV. In November of 2002, scientists developed a vaccine against the HPV-16 and HPV-18 infections, the two most prominent precuresors to cervical cancer. It is possible that, within five years, this vaccine will be available to prevent the contraction of HPV, thereby eliminating the possibility of their causing cervical cancer.
Dr. Douglas Lowy, a National Cancer Institute scientist developed the vaccine. Since its creation, the government has given the rights to develop the vaccine to two companies: Merck and GlaxoSmithKline. The latter is currently calling the vaccine Cervarix.
Scientific testing is currently underway to determine the effectiveness and the possible side effects of Cervarix. The study, published in both the New England Journal of Medicine and in the Journal of the American Medical Association, involved 2,392 women from 16 to 23 years of age. The women were randomly chosen to receive three injections, given at day zero, month two and month six, of either a placebo or an HPV-16/HPV-18 vaccine. All of the women tested negative for the HPV-16 infection at the time of their enrollment in the study. Of the women who received the placebo, 41 developed an HVP-16 infection, and nine of these women went on to develop precancerous lesions on their cervixes. In contrast, none of the women who received the vaccine developed an HPV-16 infection.
Based on the results of the study, scientists said the vaccine was 91-percent effective against infection with the two most dangerous strains of HPV, and it provided 100-percent protection against the persistent infections that can lead to cancer. According to the scientists who conducted the study, the vaccine is safe and produced few side effects. However, the vaccine does not prevent HPV-16 or HPV-18 infections already present in a patient from progressing to cancer.
If this vaccine makes it to the market, it will be the second developed to prevent cancer. The first is the vaccine developed to fight hepatitis B, which has greatly reduced the number of infections that lead to liver cancer. Both vaccines take a similar route, immunizing against a seperate virus that is known to be a major cause of a particular cancer.
A second study was done that looked at the relation between the incidence of developing cervical cancer, the new HPV-16/HPV-18 vaccine and the frequency of screening. The study, published in the August 13, 2003 issue of the Journal of the American Medical Association, showed that although the vaccine prevented the contraction of a persistent HPV-16 or HPV-18 infection in sexually active women, those who received “vaccination [in conjunction with] annual screening beginning at age 18 had the largest overall reduction in cancer incidence and mortality.”
This may seem like an obvious conclusion, but according to one national health survey, one fifth of women between the ages of 18 and 64 have not had a pap smear test in the last three years. Being tested for STDs and precancerous lesions is arguably the most important way a woman can prevent the contraction of a serious infection like the one that can lead to cervical cancer.
Even if this new HPV vaccine never does make it to the market, these studies further confirm that regular screening plays an essential role in preventing STD infection. While experts hope that in a few years time there will be a widespread vaccination against HPV-16 and HPV-18, they recommend that women are tested annually for STDs.
