Wednesday, October 29, 2008

Cervical Cancer Vaccine Innovation: Still a Long Way to Go?

With one of this years Nobel Prize for Medicine’s recipient had worked for over thirty years on the virus that causes cervical cancer, will a cure be not that far behind?

By: Vanessa Uy

German-born Harald Zur Hausen became one of the recipients of the 2008 Nobel Prize for Medicine on his work on the human papilloma virus or HPV as the cause of cervical cancer. His work on the relation of HPV and cervical cancer dates back to the 1970’s. During the 1990’s, Harald Zur Hausen obtained proof on the role of the human papilloma virus in causing cervical cancer.

The Nobel assembly focused their attention on the way Harald Zur Hausen “went against current dogma” when he found that some variants of the human papilloma virus, or HPV, caused cervical cancer. He realized that genetic material like DNA of some HPV variants or species could be detected in cervical cancer tumors. Harald Zur Hausen then uncovered a family of HPV types, which only some of them cause cancer.

Cervical cancer is a form of cancer that affects women usually of childbearing age. Its tumors develop in the cervix, the entrance between the vagina and the uterus. It was only when Harald Zur Hausen’s work passed peer review scrutiny that the medical community reached the consensus that cervical cancer is caused by some variants of the human papilloma virus or HPV.

According to the work of Munoz N. et al as published in the New England Journal of Medicine published in 2003, there are more than 200 variants or types of HPV and at least 30 of these cause cervical cancer. This particular study showed that the cancer causing variants of HPV caused 99.7% of cervical cancer cases. Globally, HPV variants designated as types 16, 18, 45, and 31 account for 80% of the cases of cervical cancer.

On an incidence basis, cervical cancer is the second most common form of cancer affecting women worldwide, with half a million women diagnosed annually. Latest studies estimates that up to 50 to 80% of women will acquire an HPV infection during their lifetime. Usually via persistent infection of the cancer causing variants of HPV resulting in pre-cancerous lesions and cervical cancer.

The bad news is that human papilloma virus infection can be easily transmitted via skin-to-skin genital contact and one could become infected with the HPV virus without “normal” / “conventional” sexual intercourse. Infected men carry the HPV virus on the skin of their genitalia and yet they don’t succumb to the virus’ cancer-causing effects. Using condoms may reduce the risk but are by no means foolproof. Women who are sexually active – this means of childbearing age in a “civilized society” – are at risk of exposure to HPV variants that cause cervical cancer.

The Pap smear is currently the most important screening method that has been proven to be very good in early detection of cervical cancer. By taking a sample of cervical cells, a pathologist prepares them on a slide for microscopic examination. The microscopic examination by the pathologist determines whether the cell sample looks normal or abnormal. The earlier the pre-cancerous changes in the cervix are detected, the more positive will be the prognosis for a recovery.

The frequency of Pap smears usually varies with a woman’s age. A good point to start would be about 3 years after the start of regular sexual activity. Ideally, women should get a Pap Smear every year until the age of 30. After 30, women who have had 3 consecutive normal results on their annual Pap Smear can be re-screened every 2 to 3 years. Screening may be done if the woman has abnormal vaginal bleeding, pain, sores, or itching.

Since Harald Zur Hausen’s study of the link between human papilloma virus and cervical cancer, newer screening methods and treatments for the disease had been devised. Cervical cancer can now be detected via HPV DNA test to check for the presence of cancer-causing variants of HPV, which many doctors and gynecologists had praised for its accuracy. The development of a vaccine against cancer-causing strains of HPV has fostered a great hope in the fight against cervical cancer. Though Harald Zur Hausen says that more needs to be done since currently available HPV vaccines do not have a broad enough spectrum to combat all strains of cervical cancer-causing HPV.