Preventing HPV infection, cancer, warts and all
Gardasil protects women from infection with HPV types 6, 11, 16, and 18
Ranked as the second most common cancer in women, cervical cancer is seen in about 500,000 women each year, with over 270,000 cases resulting in death. More than half of these cases occur in the Asia-Pacific region and about four out of every five new cases occur in developing countries, where only 41 percent of women will get the necessary treatment.
In the Philippines, about two-thirds of cervical-cancer cases are diagnosed in the advanced stages, resulting in a five-year mortality rate of about 56 percent.
The Asia Oceania research organization on Genital Infections and Neoplasia (AOGIN), which held its second biennial conference on September 7 to 10 at the Shangri-La Mactan Resort and Spa in Cebu, was established in 2005 to provide "a vehicle in this region to educate on the importance of preventing cervical cancer." Cervical cancer, after all, can be prevented. It's AOGIN's goal to make sure countries in the region know how.
HPV: high and low
Prof. Suzanne Garland, AOGIN president, repeatedly describes cervical cancer as "an uncommon complication of a common condition."
Her statement stems from and highlights an important fact about the disease: cervical cancer is caused by persistent infection with the human papillomavirus (HPV), a virus that is estimated to affect up to 80 percent of women.
In fact, experts from AOGIN call cancer-causing or "high-risk" HPV infection the "necessary cause" of cervical cancer, with high-risk HPV DNA present in 99.7 percent of cervical cancers.
According to AOGIN, over 200 types of HPV have been identified, with about 40 strains transmitted through sexual contact: about 15 of them are high-risk strains, with HPV types 16 and 18 together causing 70 percent of cervical cancers worldwide.
Granted that only 10 percent of women who are infected with high-risk HPV will develop precancerous cellular changes (i.e., cervical dysplasia) and only eight percent of those women will develop early cancer and only one to two percent will develop invasive cancer, the ubiquity of the virus and ease of transmissibility nonetheless ensure the high numbers of cervical-cancer cases-and mortalities-seen both locally and worldwide. Also, experts at AOGIN say that penetrative sex is not necessary to cause infection.
The non-cancer-causing or "low-risk" HPV types cause genital warts, about 90 percent of which are caused specifically by low-risk HPV types 6 and 11 together.
Preventing HPV infection
Most infections with HPV, whether from low- or high-risk types, resolve spontaneously, indicating that the human body has the capacity to mount an effective immunological response to the virus-the conclusion being that something can be done to prevent infection and eventual progression to cervical cancer.
The fact that these infections don't resolve spontaneously, manifesting either as a persistent or recurrent infection, in those individuals who eventually develop cervical cancer suggests what that "something" might be: the human body's natural immunological response needs to be reinforced.
That's exactly what vaccination does: it primes the human immune system to recognize and destroy the virus before it can establish an infection.
A quadrivalent vaccine, conferring immunity to low-risk HPV types 6 and 11 and high-risk HPV types 16 and 18, has been developed by Merck, and has already been approved by the US Food and Drug Administration (FDA).
While trials are currently ongoing, experts at AOGIN say that the vaccine has been shown effective in preventing HPV infection by types 6, 11, 16, and 18, thus potentially reducing cervical-cancer cases by 70 percent and cases of genital warts by 90 percent.
Guidelines
In August 2006, the Advisory Committee on Immunization Practices (ACIP) issued provisional recommendations on vaccination with the quadrivalent vaccine, tentatively slated for publication in November 2006.
ACIP currently recommends immunization with the quadrivalent vaccine for females 11 to 12 years of age, and says the vaccine can be given as early as age nine. The vaccine can be given to females who have an equivocal or abnormal Pap test, high-risk test, or genital warts, but ACIP emphasizes that studies have not shown any therapeutic benefit from the vaccine.
The vaccine only protects against about 70 percent of cervical- cancer cases, and recommendations for cancer screening have not changed; however, the impact of complete coverage with the vaccine on cancer rates should not be ignored.
As such, experts at AOGIN see the vaccine as a necessary component in promoting and maintaining women's health, and hope to eliminate the stigma currently associated with receipt of the vaccine by emphasizing the ubiquity of HPV infection.
The Merck HPV vaccine is marketed under the trade name Gardasil. M
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