Additional Evidence of HPV Vaccine Effectiveness

Additional Evidence of HPV Vaccine Effectiveness

Two studies presented at the 2007 annual meeting of the American Association for Cancer Research (AACR) provide additional evidence that vaccination against high-risk types of human papillomavirus (HPV) is likely to greatly reduce the occurrence of cervical cancer.

Human papillomaviruses (HPV) consist of more than 100 different viruses. Some types of HPV cause warts on the hands or feet; others cause genital warts; and some have been linked with cancer, most notably cervical cancer. The types of HPV most commonly linked with cervical cancer are HPV 16 and HPV 18, but several other high-risk types contribute to cancer as well.

The types of HPV that cause cervical cancer or genital warts are transmitted sexually. HPV infection is extremely common and generally occurs soon after an individual becomes sexually active. Although most infections resolve on their own, some persist and can lead to precancerous or cancerous changes to the cervix, vulva, vagina, penis, and anus.

Vaccines that prevent infection with high-risk types of HPV have the potential to greatly reduce the occurrence of cervical cancer. The HPV vaccine that is currently on the market is Gardasil®, which targets HPV types 6 and 11 (which are linked with genital warts) as well as the cancer-associated types 16 and 18. Another HPV vaccine that may be approved is Cervarix, which targets HPV types 16 and 18 only. Because HPV types 16 and 18 are thought to account for roughly 70% of all cases of cervical cancer, widespread use of these vaccines would have the potential to eliminate most (but not all) cases of cervical cancer.

Updated information from a Phase II clinical trial of Cervarix, presented at the 2007 AACR meeting, suggests that vaccine effectiveness against HPV types 16 and 18 remains high for at least five-and-a-half years after vaccination.[[i]](http://news.cancerconnect.com/additional-evidence-of-hpv-vaccine-effectiveness/#_edn1 "_ednref1") Cervarix also appears to provide some cross-protection against two other high-risk types of HPV-types 31 and 45.

Another report at the 2007 AACR meeting provided updated information from a Phase III trial of Gardasil.[[ii]](http://news.cancerconnect.com/additional-evidence-of-hpv-vaccine-effectiveness/#_edn2 "_ednref2")After three years of follow-up, Gardasil remained highly protective against precancerous cervical changes related to HPV 16 and HPV 18. In addition, preliminary laboratory studies suggest that Gardasil may also provide some protection against HPV types 31 and 45.

These studies provide additional evidence of the effectiveness of Gardasil (currently on the market) and Cervarix (not yet approved).

Routine vaccination with Gardasil is recommended for girls between the ages of 11 and 12 years.[[iii]](http://news.cancerconnect.com/additional-evidence-of-hpv-vaccine-effectiveness/#_edn3 "_ednref3") The vaccine may also be given to girls as young as 9 years as well as to girls and women between the ages of 13 and 26 years.

References:

[[i]](http://news.cancerconnect.com/additional-evidence-of-hpv-vaccine-effectiveness/#_ednref1 "_edn1") Gall SA, Teixeira J, Wheeler WM et al. Substantial impact on precancerous lesions and HPV infections through 5.5 years in women vaccinated with the HPV-16/18 VLP AS04 candidate vaccine. Presented at the 2007 meeting of the American Association for Cancer Research, Los Angeles, CA, April 14-18, 2007. Abstract 4900.

[[ii]](http://news.cancerconnect.com/additional-evidence-of-hpv-vaccine-effectiveness/#_ednref2 "_edn2")Brown D. High sustained efficacy of a prophylactic quadrivalent human papillomavirus (HPV) (Types 6, 11, 16, 18) L1 virus-like particle (VLP) vaccine against cervical intraepithelial neoplasia (CIN) grades 2/3 and adenocarcinoma in situ (AIS). Presented at the 2007 meeting of the American Association for Cancer Research, Los Angeles, CA, April 14-18, 2007. Abstract LB-187.

[[iii]](http://news.cancerconnect.com/additional-evidence-of-hpv-vaccine-effectiveness/#_ednref3 "_edn3")Centers for Disease Control and Prevention. Quadrivalent human papillomavirus vaccine: recommendations of the advisory committee on immunization practices (ACIP). MMWR. Early Release March 12, 2007;56:1-24.

Related News:

CDC Guidelines Recommend Gardasil® (04/16/2007)

American Cancer Society Develops Recommendations for HPV Vaccination (3/5/2007)

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