US scientists have found evidence of a virus in malignant human prostate cancer cells, but more research is needed before we know it is a definite factor in cancer development. The virus, xenotropic murine leukaemia virus-related virus (XMRV), is already known to be capable of causing leukaemia and sarcomas in animals.
Its presence in prostate cancer cells indicates that it may also be involved in the development of some cases of prostate cancer.
Senior author Dr Ila Singh, associate professor of pathology at the University of Utah, revealed: "We found that XMRV was present in 27 per cent of prostate cancers we examined and that it was associated with more aggressive tumours.
We still don't know that this virus causes cancer in people, but that is an important question we're going to investigate. We still don't know that this virus causes cancer in people, but that is an important question we're going to investigate.
The study, which also involved scientists at Columbia University, looked at tissue taken from more than 200 human prostate cancers, as well as more than 100 non-cancerous prostate samples. Twenty-seven per cent of cancers contained XMRV, compared with just six per cent of benign tissues.
Publishing their findings in the Proceedings of the National Academy of Sciences, the researchers noted that the virus was almost exclusively found in malignant prostate cancer cells, indicating that it may be involved in the development of tumours.
They also pointed out that susceptibility to infection with XMRV does not appear to be affected by the presence of a genetic mutation, suggesting that all men may be at risk rather than just those with a certain genetic make-up.
Although her theory is yet to be proven, Dr Singh believes that the virus may insert a copy of its genes into the DNA of prostate cells, close to a gene that regulates cell growth. This may cause the cell to multiply rapidly, leading to cancer.
Dr Chris Parker, Cancer Research UK's prostate cancer expert at the Institute of Cancer Research, said: "This exciting study finds a virus, similar to that which can cause certain cancers in animals, in human prostate cancer cells. It raises the possibility that the virus might contribute to the development of some prostate cancers.
"Right now, this is a possibility that needs to be tested. But in the future, if it turns out to be true, then we could speculate about the possibility of vaccination to protect against prostate cancer, similar to the approach now used to prevent cervical cancer."