A study of a vaccine that targets one of the main causes of cervical cancer showed promising results, according to a report published in a recent issue of the New England Journal of Medicine. The vaccine targets a certain strand of the human papillomavirus (HPV), a common sexually transmitted disease that can increase the risk of cervical cancer. In the study, women who were given the vaccine were protected against cervical cancer while women who were given inactive inoculations were more likely to experience pre-cancerous cervical tissue changes. While the women need to be followed for a longer period of time to determine whether the vaccine remains effective, the results provide hope that a cervical cancer vaccine will be available in the near future.
The International Agency for Research on Cancer estimates that nearly 380,000 women are diagnosed with cervical cancer worldwide each year. The number of cases and number of deaths from cervical cancer are higher in less developed countries where routine screening is not widespread. Human papillomavirus (HPV) is a sexually transmitted disease; certain strains of HPV increase the risk of cervical cancer.
There are over 80 different strains of HPV, affecting more than 40 million Americans. While the majority of HPV strains do not pose health risks, a few strains increase the risk for cervical cancer (such as HPV-16, HPV-18, HPV-31, and HPV-45). The HPV-16 strain has been shown to cause about 50% of cervical cancer cases.
To test whether a vaccine may be effective against the HPV-16 strain, Laura A. Koutsky, Ph.D. of University of Washington and colleagues compared the effectiveness of an HPV-16 strain vaccine versus a placebo (inactive substance) on 2,392 women between the ages of 16 and 23. The study was funded by Merck and Co. Of the women who received the vaccine, none developed HPV-16 infections or cervical tissue changes. Among the 765 women who did not receive the vaccine, 41 developed HPV-16 infections and nine developed pre-cancerous cervical changes, often a precursor to cervical cancer. Women given the vaccine also developed approximately 60 times more antibodies against HPV-16 than the non-inoculated women.
Though the results of the study are promising, the women were only followed for an average of one and one half years, not long enough to determine whether the vaccine provides lasting protection. Nevertheless, some experts predict that an HPV-16 could be available in the United States within five years. Because this vaccine only targets the HPV-16 strain, it would not eliminate all forms of cervical cancer.
A vaccine for cervical cancer could significantly reduce the number of deaths from the disease, particularly in developing countries where screening remains low. For the time being, all women 18 years of age and older should have annual Pap smears to help screen for cervical cancer. Some women who have had multiple Pap smears with negative results may need to be screened less often, according to a doctor’s instructions.
Risk factors for cervical cancer include age (the highest risk occurs between late teens and mid-thirties), early age at first sexual intercourse, multiple sexual partners, certain strains of HPV, smoking, and daughters of women who took DES (a hormonal drug prescribed between 1940 and 1971 to help prevent miscarriages). Symptoms that may be associated with cervical cancer include unusual vaginal discharge, vaginal bleeding, or bleeding or pain during sexual intercourse.
- The report, "A Controlled Trial of a Human Papillomavirus Type 16 Vaccine," is published in the November 21, 2002 issue of the New England Journal of Medicine, http://content.nejm.org/
- To learn more about cervical cancer and HPV, please visit http://www.imaginis.com/cervical-cancer/
