Posts Tagged ‘cervical cancer’

Vaccines for cervical cancer

February 14, 2008

Worldwide, cervical cancer is the second-leading cause of cancer deaths among women. The FDA estimates that it causes more than 470,000 new cases and 233,000 deaths worldwide per year. About 3,400 women in the United States die from cervical cancer every year. Regular Pap smear testing has reduced the number of women in the United States who are diagnosed with cervical cancer to about 10,000 per year. According to the FDA, for women who develop cervical cancer, Human Papillomavirus (HPV) is generally the cause.

The American Cancer Society suggests that women begin cervical cancer screening about three years after they begin having vaginal intercourse, but no later than age 21. Screening should be annual with the regular Pap test. At age 30, women who have had three normal Pap test results in a row may reduce screenings to every two to three years. About half of all females diagnosed with cervical cancer are between the ages of 35 and 55 years old. However exposure often occurs during these women’s teens or 20s.

Lucky for those who fall in this age range, Merck & Co. developed the Gardasil vaccine which protects against the four most dangerous strains of HPV: 6, 11, 16 and 18. Types 16 and 18 are responsible for causing about 70 percent of cervical cancers and types 6 and 11 cause about 90 percent of genital wart cases. According to the Centers for Disease Control and Prevention, about 80 percent of the infections clear up, but one in six of those infected with HPV will develop genital warts while one in 1,000 will be diagnosed with cervical cancer.

How Gardasil works:

Gardasil is a recombinant vaccine, which is created by genetic engineering in which the genetic material of an organism is manipulated. According to the FDA Web site, the genes which code for a specific protein from each of the four virus types of HPV are expressed in yeast in order to create large quantities of the protein. The body’s immune response to the recombinant proteins then protects against infection by the naturally occurring virus.  

The vaccination consists of three shots, administered intramuscularly in the upper arm or thigh, which are given over a period of six months. Two months after the initial dose, the second dose is administered. The third dose is given six months after the first dose. The vaccine reaches its peak protection about one month after the third shot and lasts for at least five years.

But just how effective is Gardasil:

The American Cancer Society reported in February 2007 that most HPV infections, even carcinogenic ones, resolve without treatment. About 75 percent of infections in adults and 90 percent of those in adolescents disappear on their own. The vaccination is most effective before the onset of sexual activity but is recommended regardless of sexual history. If the vaccine is given before sexual activity has begun, it protects nearly 100 percent against an infection by the four genital HPV strains. For those who are already sexually active, the vaccine boosts the immune system and helps the body shed the virus.

There are over 100 different strains of HPV. It is important to remember that Gardasil does not protect against the types of HPV that are not included in the vaccine, which can also cause some cancers. Additionally, women are not protected if they were previously infected with the HPV type(s) which are covered by the vaccine, prior to vaccination. Furthermore, Gardasil is not a treatment for HPV, only a preventative measure. But if a female is currently infected or has been in the past with a vaccine-related HPV type, the vaccine will protect her against the remaining HPV types contained in the vaccine.

Information for college students:

  • The University of North Carolina at Chapel Hill provides information to students about HPV and Gardasil during freshman orientations. Additional information is available at student health services. UNC-CH charges $426 for the three Gardasil shots. 
  • At North Carolina State University, information about HPV is provided only when students go to the center’s women’s health services. NCSU charges $453 to administer the three shots. 
  • Duke University student health center offers information sessions about HPV and cervical cancer twice a week. Those interested in being vaccinated can receive their first shot immediately following the session. Duke charges $420 for the vaccine.

New Development:

GlaxoSmithKline, which has its U.S. headquarters in Research Triangle Park, also has a cervical cancer vaccine in the works. Their version, Cervarix, will exclusively target the HPV strains which can cause cervical cancer.

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