Scientists have produced compelling evidence that a virus known to cause cancer in animals is linked to prostate cancer in humans.

科学家发现强有力的证据证明一种导致动物患癌症的病毒与人类的前列腺癌有关。

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Prostate cancer is a major killer

The researchers from the University of Utah and Columbia University medical schools found the virus in 27% of the 200 cancerous prostates（前列腺） they looked at.

They say it was associated with more aggressive tumours² and found in only 6% of non-cancerous prostates.

The finding raises the prospect³ of one day producing a vaccine⁴.

Previous research has linked XMRV (Xenotropic murine leukaemia virus) to prostate cancer but not specifically to the aggressive form of the disease.

Retrovirus

XMRV is a retrovirus（逆转录酶病毒） like HIV which works by inserting a copy of its own DNA⁵ into the chromosomes⁶（染色体，无足轻重的小人物） of a cell they infect.

Where this occurs next to a gene⁷ that regulates cell growth it can disrupt（分裂，瓦解） the normal development of the cell.

XMRV is known to cause leukaemia（白血球过多症） and other tumours in animals.

Dr Ila Singh, who led the study from the pathology（病理学） department at the University of Utah, said: "We still don't know that this virus causes cancer in people, but that is an important question we are going to investigate.

"One of the things peculiar⁸ about this virus is that it has an androgen（男性荷尔蒙） response element - it grows better in the presence of testosterone（睾丸素） and possibly other steroid hormones⁹（甾体激素）.

"This is particularly interesting because if we can prove that it responds to oestrogen（雌激素） it could have a role in other cancers.

"We are already looking at the bodies of 100 women and 100 men, who died from other causes, to see if any other organs carry the virus."

Risk factor

Dr Helen Rippon, Head of Research Management at The Prostate Cancer Charity, said the research was intriguing¹⁰（吸引人的，有趣的） but posed several key questions about the role the infection plays in prostate cancer.

She said: "Around the world, extensive work is being undertaken to identify risk factors for prostate cancer which will enable treatments and tests for the disease to be refined.

"It is critically important to identify key triggers of prostate cancer to improve early detection of the disease in men with potentially life threatening prostate cancer."

Dr Chris Parker, Cancer Research UK's prostate cancer expert at the Institute of Cancer Research said: "This exciting study raises the possibility that the virus might contribute to the development of some prostate cancers.

"In the future, if it turns out to be true, then we could speculate about the possibility of vaccination¹¹ to protect against prostate cancer, similar to the approach now used to prevent cervical（颈，颈部） cancer."