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Viral cause for prostate cancer?

Prostate cancer is increasingly looking like an infectious disease, a new study shows, and may be sexually transmitted

By | September 7, 2009

Mounting evidence suggests that prostate cancer is an infectious disease caused by a recently identified virus. The linkurl:latest report,;http://www.pnas.org/cgi/doi/10.1073/pnas.0906922106 published today (September 7) in the Proceedings of the National Academy of Sciences, found the virus was associated especially with aggressive prostate cancers and noted that "all individuals may be at risk" for infection.
Human prostate cancer tissue. Brown,
granular staining shows malignant epithelial
cells that express XMRV proteins

Image: R. Schlaberg and H. M. Thaker
The notion that prostate cancer is an infectious disease like cervical cancer would not surprise most cancer experts, said linkurl:Ila Singh;http://www.path.utah.edu/research/cbi/ila-singh-md-phd of the University of Utah, the study's senior author. Almost 20% of visceral cancers are now proven infectious diseases, and there is a lot of indirect evidence from epidemiology and genetics that prostate cancer may be one of them. The suspect is xenotropic murine leukemia-related virus (XMRV), a gammaretrovirus similar to viruses known to cause cancer in animals. Researchers at Columbia University and the University of Utah found the virus in more than a quarter of some 300 prostate cancer tissue samples, especially in malignant cells. That prostate cancer is a viral disease is not yet proven, but this is the third independent confirmation that XMRV infects prostate tissue. Singh pointed out that clinicians badly need better tools for distinguishing between prostate cancers that are potentially deadly and those that develop so slowly that the affected men die of something else. "We have no idea if this virus is such a marker but it clearly needs to be investigated further," she said. Research has long hinted that prostate cancer, also like cervical cancer, is a sexually transmitted disease. linkurl:Eric Klein;http://my.clevelandclinic.org/staff_directory/1/Staff_393.aspx and colleagues at the Cleveland Clinic in Ohio linkurl:reported in July;http://www.ncbi.nlm.nih.gov/pubmed/19403677 that both human semen and one of its major components, acid phosphatase, increase XMRV infectivity for prostate cells 100-fold. They also found the virus in prostatic secretions of men with prostate cancer. "That really strongly suggests that XMRV is sexually transmitted," he said. Klein was part of a group in Cleveland and the University of California, San Francisco, that in 2006 linkurl:first identified;http://www.ncbi.nlm.nih.gov/pubmed/16609730 XMRV in prostate tumors. He was not involved in today's paper. Klein said the July findings suggested a biological mechanism for sexually transmitted XMRV infection. If a man with viral particles in his lower genital tract has intercourse and deposits semen in his partner, acid phosphatase in the semen could increase the virus's ability to infect prostate tissue of the partner's subsequent partners. Singh cautioned, "We can't really say that it's an STD at this point." Her lab is looking for XMRV in semen and also in women's cervical samples. Many steps lie ahead for demonstrating conclusively that an infectious agent, in particular XMRV, causes prostate cancer. One approach is to inject lab animals with the virus and follow the results. Researchers have been trying to develop an animal model, but XMRV, although derived from a mouse virus, has since acquired an envelope that prevents it from infecting most strains of lab rodents, according to Singh. Klein's colleagues are working on a monkey model. Klein and his colleagues linkurl:showed last year;http://www.ncbi.nlm.nih.gov/pubmed/18684813 that XMRV integrates into host DNA. So another proof would be to demonstrate that XMRV inserts near a gene that promotes cell growth. "That would be very convincing proof for most people that the retrovirus is involved in causing cancer," said Singh. Her group is working on that possibility with linkurl:Frederic Bushman,;http://www.med.upenn.edu/camb/faculty/mv/bushman.html a microbiologist at the University of Pennsylvania. Establishing an infectious cause for prostate cancer would offer men something they have never had before: potential ways of preventing this common deadly disease. The new paper emphasizes how establishing a viral cause for prostate cancer could affect biomedical research. It would trigger epidemiological studies, vaccine development, and studies on interference with viral replication and antiviral therapies. Klein noted that the US National Cancer Institute is now encouraging collaboration on XMRV studies among far-flung research groups. Prostate cancer strikes 1 in 6 US men and is the second-most common type of cancer in men, after skin cancer. Except for lung cancer, it also causes the most cancer deaths in men. Correction (September 23): A previous version of this story incorrectly stated that skin cancer causes more deaths than prostate cancer in men. In fact, lung cancer and prostate cancer, respectively, cause the most cancer deaths in men. The Scientists regrets the error.
**__Related stories:__***linkurl:Silenced genes drive viral cancers?;http://www.the-scientist.com/blog/display/55410/
[9th February 2009]*linkurl:When cancer is just the beginning;http://www.the-scientist.com/article/display/55048/
[October 2008]*linkurl:The ecology of tumors;http://www.the-scientist.com/article/display/23272/
[April 2006]
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Comments

Avatar of: Karen Smallwood

Karen Smallwood

Posts: 3

September 8, 2009

If indeed it does come to light that prostate cancers are spawned from a virus, it may cause some interesting dilemmas for some happily married couples. Similar to the discovery of genital herpes when a young couple goes in for a prenatal workup, virally transmitted prostate cancer could possibly shake otherwise successful marriages of many years. It will be interesting to see what comes out in the wash.
Avatar of: anonymous poster

anonymous poster

Posts: 85

September 8, 2009

Once upon a time, a LONG LONG time ago, there was this idea that human cancers, JUST LIKE MANY MANY KNOWN NON-HUMAN ANIMAL CANCERS, are of viral etiology. Remember Rous sarcoma virus? That was a long time ago indeed. \n\nBut even as knowledge of animal cancer viruses accumulated (mouse tumor viruses, chicken tumor viruses, even cat tumor viruses like Feline Leukemia), the rigid notion that somehow human cancer was different took hold. People lost their scientific credibility -- and sometimes even their faculty jobs -- by merely suggesting that human tumors and leukemias might have a viral origin. As human cancer viruses became apparent, the field of cancer biology viewed each in turn as "the exception that proved the rule," the "rule" being that human cancers were by and large NOT viral in origin. \n\nSo, how many bona fide human cancer-causing viruses do we need to recognize in order to really question the prevailing dogma of the cancer biology field? \n\n\n\n
Avatar of: anonymous poster

anonymous poster

Posts: 5

September 8, 2009

It would seem like an straightforward, comparative study to look at males who have (had) higher than normal sexual activity versus those who had little (or no) sexual activity and see who develops prostate cancer.
Avatar of: anonymous poster

anonymous poster

Posts: 4

September 8, 2009

If the model related is correct, then it seems that a monogamous couple with only one lifetime partner should never have prostate cancer. This seems very easy to check epidemiologically (although one would have to account for lying).
Avatar of: Susan Colilla

Susan Colilla

Posts: 3

September 8, 2009

This is very interesting finding and I have suspected that most cancers have a viral etiology. My master's thesis did not find an association between increased number of sexual partners and prostate cancer when looked directly, but did find a highly significant association and interaction between high number of lifetime sexual partners (10+) and men who had a first degree relative with prostate cancer. Unfortunately, due to political reasons, I was not permitted to publish this finding (just used it as my master's thesis). Since the majority of people are exposed to these viruses (HPV etc), the rate limiting factor for how soon a man develops prostate cancer may be his personal genetic makeup. \n
Avatar of: anonymous poster

anonymous poster

Posts: 7

September 8, 2009

Can a viral agent explain so-called diseases of civilization such as cancers of the endocrine organs like the prostate? Perhaps "Western" populations have a higher incidence of the virus which was in turn spread to pre-industrial societies that merged with Western cultures (e.g., hunter gatherer or agrarian cultures that adopted Western colonial foods and lifestyles). A viral cause seems unlikely to explain diseases of civilization but it's worth exploring.
Avatar of: Jennie Burke

Jennie Burke

Posts: 3

September 8, 2009

There is also an extremely high level of Mycoplasma infection found in prostate cancer tissue. The one we have found in our laboratory to be most prevelant is M.fermentans - known to trigger Interleukin cascades and switch on oncogenes.\nThe history of research into cancer as infection is worth re-studying.
Avatar of: RICHARD J ABLIN

RICHARD J ABLIN

Posts: 2

September 9, 2009

Certainly very interesting. It is perhaps, of interest to also note, among other earlier studies, those of Mukta Webber (Michigan State, Ann Arbor) and the extensive studies of the late Leon Dmochowski (University of Texas, Houston) and Yuji Ohtsuki (Kochi Medical School, Nankoku, Japan), who described in the 1970's, virus particles, e.g., HSPV-2, CMV; virus-like particles resembling type C virus particles, and/or virus-like information, e.g., viral p30 protein and RNA-dependent DNA polymerase, in the benign and malignant human prostate. We and others have also alluded to evidence for the presence of HIV and KSHV (HHV-8) in the human prostate.
Avatar of: Dr. Kas Mohammed

Dr. Kas Mohammed

Posts: 1

September 9, 2009

From the articles read thus far, it appears that the causative agent for prostate cancer maybe in part due to a virus. These findings should stimulate additional research.
Avatar of: Jesse Creel

Jesse Creel

Posts: 12

September 10, 2009

I would like to see a comparison of this Xenotropic MuLV-related virus VP62 sequences to HTLV 1&2, HIV 1&2 and pathogenic HERVs for conserved sequence homology with the hope that we could make a vaccine which covers one or more in one vaccine.\n\nJesse Creel\nVaccine Research Advocate
Avatar of: anonymous poster

anonymous poster

Posts: 40

September 11, 2009

I have no doubt that both my parents had sex only with each other during their lives. Yet my father got prostate cancer, not a particularly invasive case, and was successfully treated for it.
Avatar of: Dov Henis

Dov Henis

Posts: 97

September 12, 2009

[Comment posted 2009-09-11 12:25:37]\nQuote:\nI have no doubt that both my parents had sex only with each other during their lives. Yet my father got prostate cancer, not a particularly invasive case, and was successfully treated for it.\n\nIMO in several cases operating physicians diagnose PC where it is doubtful then proceed to treat it successfully...\n\n
Avatar of: Christopher Lee

Christopher Lee

Posts: 50

September 16, 2009

I remember reading in the early 1960s an article from an authoritative source that the "policy" that the majority of human cancers were due to carcinogens was no more than a working hypothesis: somebody had to decide where to place the reasearch funds, and it was admitted that this amounted to placing a bet.\n\nKnown causes (tobacco, soot (scrotal cancer), asbestos, beta-napthalene) undoubtedly influenced the decision, and of course natural carcinogens (aflatoxins, (partly natural) dioxins were discovered subsequently.\n\nThe difficulty was, and still is, to nurture minority or fringe ideas, without going off in all directions at once.
Avatar of: John Bell

John Bell

Posts: 2

September 16, 2009

The PSA test has always been difficult to interpret. First off the mark with a new test for this virus could be in the money.
Avatar of: anonymous poster

anonymous poster

Posts: 3

September 16, 2009

I call BS on this "finding." Everyone knows that the best way to fund research is infer some looming danger like "prostate cancer is contagious!" Throw in the caveat that it is "sexually transmitted" and you have hit the jackpot. \n\nHow many completely monogamous Iowa farmers have to die from prostate cancer before this myth gets put to rest?
Avatar of: anonymous poster

anonymous poster

Posts: 1

September 16, 2009

From the article: "Prostate cancer strikes 1 in 6 US men and is second only to skin cancer in causing their deaths from cancer."\n\nSkin cancer? Is this an error?
Avatar of: anonymous poster

anonymous poster

Posts: 4

September 16, 2009

The suspect is xenotropic murine leukemia-related virus (XMRV), a gammaretrovirus similar to viruses known to cause cancer in animals.
Avatar of: anonymous poster

anonymous poster

Posts: 1

September 16, 2009

This is a great article that everyone should read. I am a little freaked out and relieved all at the same time!
Avatar of: anonymous poster

anonymous poster

Posts: 19

September 16, 2009

Folks, you **don't** have to have sex to be exposed to an animal virus such as this....they are endemic,and rodents contaminate much (foodstuffs, surfaces). I know no one like to think about that!! But, viruses are all around us, and will probably be found to be culprits (along with Mycoplasma and probably some fungi)in most human cancers - my prediction;let's see how right I am! My mother (high school grad only) always espoused this theory when I was growing up, driving me crazy with washing my hands etc after visiting people who had cancer. I used to pooh-pooh her, but no more after my Ph.D.!! \n\nAfter you get the initial infection, it may be tropic for the prostate (or cause particular problems there because of the properties of the cells there);hence "the monogamous Iowa farmers" etc. still coming down with prostate cancer....no implications of hanky panky needed....\n
Avatar of: anonymous poster

anonymous poster

Posts: 26

September 16, 2009

1) Study after study show that people who initially claim to be monogamous are not. Paternity tests, for both humans and "monogamous" animals, routinely provide "surprising" results.\n\n2) Since this virus is xenotrophic, I wouldn't be surprised if the Monogamous Iowa Farmers contract it by mating with their livestock - that doesn't count as "cheating" does it?\n\nBaxter Zappa
Avatar of: anonymous poster

anonymous poster

Posts: 1

September 17, 2009

Why does everyone act like cancer, even cancer of one particular organ, system or tissue, is one single entity? Cancer is dysregulated growth of abnormal cells. Given this, I do not see why there can't be viral, bacterial, genetic and environmental ( i.e. chemical mutagens)causes for a "single" disease like PCa. It seems pointless to use the "monogamy" argument to argue about this like there can only be one cause to explain all cancers of the prostate. It is an oversimplified view to assume just because some PCa is likely to be viral in origin thatall PCa must be.

September 17, 2009

The latest statistics (2009) by the American Cancer Society show that lung cancer causes 30% of death by cancer in the US and prostate cancer only 9%. Melanoma represent only 5% of cancer cases vs 25% for prostate cancer and 15% for lung cancer. Who reviewed that article?
Avatar of: anonymous poster

anonymous poster

Posts: 1

September 18, 2009

If you look at just the male population prostate cancer represents 25% of cancer cases. This is followed by 15% being lung cancer. Only 5% of the cases are melanoma. These numbers change when you account for the male and female population together. Also, the ACS does not include other cancers of the skin in these statistics because it would largely skew the other results due to the drasticaly high numbers of cases compared to other cancers. \n\nRight now the only risk factors for prostate cancer are age, race, and family history. So any insight into another factor is a great step even if it is not found in all cases and much more research needs to be done for validation.

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