- A virus that is known to cause certain forms of cancer in animals has been found in the cancer cells of humans with prostate cancer.  This is according to an article in the September issue of the journal Proceedings of the National Academy of Sciences.
· Prostate Cancer is the most common form of cancer found in men in the United States and the second most common cause of cancer death in men.

· Investigators report that the virus, Xenotropic murine leukemia virus-related virus (XMRV) was discovered in human prostate cancer cells.  This virus was not previously known to infect humans.  In animals it is responsible for such cancers as feline (cat) leukemia.
The study authors examined 334 prostate tissue specimens, with 233 specimens from men with prostate cancer and 101 from men without prostate cancer.  Investigators found the virus in 27% of the specimens with prostate cancer.  Additionally, the specimens with the virus were associated with more aggressive forms of prostate cancer.

· The Xenotropic murine leukemia virus-related virus is a special type of virus that is able to infect the DNA of a cell which can lead to mutations and the development of cancer.

· The concept of an infection leading to cancer is not a new idea.  The Human papilloma virus (HPV) is another example of a virus that can cause cancer and is associated with the development of cervical cancer. Burkitt lymphoma is caused by the Epstein Barr virus which infects lymphocytes and causes a specific mutation of the DNA leading to lymphoma.

Although not all of the prostate cancer specimens were infected with the virus, this is a very important finding for at least some prostate cancer cases and indicates a probable association between this viral infection and prostate cancer.  Prostate cancer is one of the most common forms of cancer and this finding may lead to new forms of treatment in the future.

The fact that this animal virus was found in human cells is also very important and should lead to more research into whether this virus is a responsible for other forms of cancer.

Cristopher Geiler, M.D.

Reference
Proceedings of the National Academy of Sciences
Proc Natl Acad Sci U S A. Published online September 7, 2009.