Four out of five people are believed to have been exposed to human papilloma virus – HPV – which can cause genital warts and cervical cancer. Two vaccines are available to prevent infection by some HPV, Gardasil, marketed by Merck, and Cervarix, marketed by GlaxoSmithKline.
Both protect against initial infection with HPV types 16 and 18 - causing around 70% cervical cancer. However, Gardasil also protects against HPV types 6 and 11 - which cause 90% of genital warts. Most importantly, the Gardasil vaccine is the only vaccine that also protects men against genital warts, throat and anal cancers ::::
An ongoing study of 4,065 males demonstrated the efficacy of Gardasil in males who did not have HPV infection prior to vaccination. The vaccination is expected to protect against penile cancer and anal cancer caused by included HPV types, and research in this area is ongoing.
Many health experts have spent years campaigning for the change. A breakthrough came last year when the Pharmaceutical Advisory Committee recommended the Immunise Australia Program be widened to include vaccinating boys in their first year of high school.
Dr Steve Hambleton, the president of the Australian Medical Association, says today’s announcement will make Australia a leader in the battle against the sexually transmitted virus. He says HPV is known to cause a variety of cancer types in both men and women.
“Persistent HPV infections is associated with approximately 85 per cent of anal cancers, 50 per cent of penile cancers, 70 per cent of vaginal cancers and 40 per cent vulval cancers and so treating both men and women will decrease the prevalence of these diseases significantly,” Dr Hambleton said.
An HPV vaccine has been given to young girls since 2007. Ever since, there have calls to broaden the scheme to include boys. The research that led to the development of the vaccine began in the 1980s by groups at the University of Rochester,Georgetown University, and the US National Cancer Institute.
Professor Ian Frazer is the brains behind the Gardasil vaccine. In 2006, he was named Australian of the Year but he still endured plenty of criticism.
Judy Wilyman of Wollongong University argues the link between HPV and cervical cancer is based on assumptions. In an article published by the British Society for Ecological Medicine, she says 90 per cent of women infected with the virus do not develop the disease.
But Dr Hambleton disagrees. ”This is one of the most potent vaccines that we have and we know that cervical cancer in women is related to HPV vaccine but with anal cancers, penile cancers, it is timely that it is actually extended to boys,” he said.
And cancer and vaccine experts aren’t convinced either by Wilyman’s arguments, saying the HPV vaccine is the best way to prevent cervical cancer.
“One of the best things you can do for your daughter is to have her vaccinated against HPV,” says Associate Professor Karen Canfell at Cancer Council NSW, adding that it is a leading form of cancer among women. She says recent evidence from the International Agency for Research on Cancer shows that HPV rates do track cervical cancer rates if you take into consideration screening, which allows early intervention in cervical cancer.
Canfell agrees the majority of HPV infections don’t lead to cervical cancer and that some other factors are required for a woman to develop cancer.
“It’s termed a necessary but not sufficient cause,” says Canfell, an epidemiologist specialising in cervical cancer.
She says according to IARC studies the main “cofactors” that accelerate the progression of cervical cancer are a woman giving birth to a high number of children, giving birth at a younger age, using oral contraception and smoking.
But Canfell says despite these cofactors, HPV is the “primary cause” of cervical cancer, and this is exactly the rationale behind having an HPV vaccine.
In 1991, Australian investigators at The University of Queensland found a way to form non-infectious virus-like particles - VLP - which could also strongly activate the immune system. However, these VLPs assembled poorly and did not have the same structure as infectious HPV.
In 1993, a laboratory at the US National Cancer Institute was able to generate HPV16 VLPs that were morphologically correct. These VLPs were the basis for the HPV16 component of the Gardasil vaccine. Upon commercialization of the vaccine, controversy involving intellectual property arose between the various groups that played a role in developing the vaccine.
Once an HPV virion invades a cell, an active infection occurs, and the virus can be transmitted. Several months to years may elapse before squamous intraepithelial lesions (SIL) develop and can be clinically detected. The time from active infection to clinically detectable disease may make it difficult for epidemiologists to establish which partner was the source of infection.
In a study undertaken by researchers at the National Cancer Institute, researchers have revealed some shocking findings. The most shocking was the revelation that as many as 72 percent of throat tumors in men may be linked to HPV. The researchers hypothesize that the virus spreads predominately via oral sex, and that it may already account for more cases of throat cancer than smoking. The researchers, headed by Maura Gillison MD, PhD, professor of medicine and Jeg Coughlin Chair of Cancer Research at The Ohio State University Comprehensive Cancer Center in Columbus, report that there has been a dramatic increase in the incidence of oropharyngeal cancer since 1984. A growing majority of new cases (70%) are associated with HPV, and the vast majority of patients are male.
8 October 2011: Human Papillomavirus – HPV – has been all over the medical journals and alerts of late. In the U.S. theres an epidemic going on right now, raising concerns about, well, oral sex and throat cancer. First hypothesized in 2005, a research study at the College of Malmö in Sweden suggested that performing unprotected oral sex on a person infected with HPV might increase the risk of oral cancer. The study found that 36 percent of the cancer patients had HPV compared to only 1 percent of the healthy control group. Read the full article »»»»
source: abc science
image source: flickr