A human papillomavirus (HPV) infection can either directly or indirectly cause a malignant tumor to develop in the prostate, according to Australian researchers.
Professor James Lawson and Dr. Wendy Glenn of the University of New South Wales, Australia, say there are indications for a possible link between the human papillomavirus (HPV) and prostate cancer after reviewing 26 studies.
The two authors say high-risk types of HPV, types 16 and 18, were identified in all types of prostrate tissue —normal or healthy, benign and malignant.
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HPV types 16 and 18 are also responsible for the majority of types of cervical cancer. Lawson and Glenn say there is evidence that those high-risk types of HPV are present in prostate cancer more often than in healthy or benign tumor tissue.
"Although HPVs are only one of many pathogens that have been identified in prostate cancer, they are the only infectious pathogen we can vaccinate against, which makes it important to assess the evidence of a possible causal role of HPVs in prostate cancer," says Lawson.
The researchers' previous work has also found evidence of Epstein Barr virus (EBV) in malignant prostate cancers.
They have published their latest paper in the scientific journal, Infectious Agents and Cancer.
More studies needed
"There have been a number of publications since 2005, which have shown an association between HPV and the formation of prostate cancer," says Prof. Peter Hammerer, director of urology at the Braunschweig Clinic (Klinkum Braunschweig). "They are all just association studies. There's still no scientific evidence for a link."
More studies are needed. Prof. Michael Muders at the University Hospital Bonn says important studies have yet to be done, including those in cell cultures and animal tests.
Muders says experiments with cell cultures could involve inserting oncogenic HPV of high-risk subtypes, such as Subtype 16 or 18, into non-neoplastic cells using genetic manipulation. But they could also involve animal experiments with such cells.
"It's studies like that which will confirm an association between HPV and a malignant transformation of prostate glands, and leave no room for doubt," says Muders.
Infection is easy
HPV is usually associated with cervical cancer in women. But young men and boys can also get infected and then, in turn, infect their partners, because HPV is a sexually transmitted infection.
The virus can even be transmitted via oral sex. If it infects the lining of the mouth, HPV can cause tumors there as well.
While HPV is highly infectious, not all types of the virus are dangerous. So-called low-risk types can cause genital warts. Most often they appear at the anus or genitals — with men it's mostly the penis. To begin with, they may appear as warts and then continue to develop and grow. There are 200 different types of papillomaviruses.
Means and measures to protect yourself against HPV will differ from country to country. But in Germany, a Standing Committee on Vaccination ("STIKO") has advised for 10 years that girls should be vaccinated against HPV between the ages of nine and 14 years.
"Medically speaking, a HPV vaccination in girls and boys is the primary way to prevent cervical cancer," says Muders. "It can also protect against squamous cell carcinomas in the ear-nose-throat region."
Squamous cell carcinomas include forms of skin cancer.
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People who have been infected with HPV can often show no visible symptoms. It make the disease unpredictable. You can get infected, even without having sex, such as through a "smear infection," or contact with a contaminated surface. That could happen in a sauna.
The vaccine is effective against the most important forms of the virus. Those are HPV 18 and HPV 18. Both types can cause cancer. Studies suggest that the vaccine can provide up to 95% protection against tumors and pretumors.
"A prophylactic vaccination can probably reduce the risk of HPV-induced cancer," says Hammerer.
The only known side-effects of the vaccine are a possible swelling and reddening at the site of the injection, as is the case with other vaccines. But given the expert opinion, young boys and girls should be able to live with that for the benefit of protection against HPV and a possible cancer.