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Virus implicated in breast cancer

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The mouse mammary tumor virus, or MMTV, whose human equivalent has now been strongly associated with breast cancer

The mouse mammary tumor virus, or MMTV, whose human equivalent has now been strongly associated with breast cancer A newly-discovered virus has been found in the diseased tissue of nearly half of women with breast cancer in Australia, opening up new avenues for preventative and treatment vaccines.The research, undertaken by Caroline Ford, a doctoral student at the University of New South Wales in Sydney, has shown that the virus appears in the breast tissue of over 40% of women with breast cancer – but very rarely in cancer-free breast tissue.The work is looking at a human version of the mouse mammary tumour virus (MMTV), the best-known oncogenic – or cancer causing – virus in science. In mice, 95% of mammary cancers are caused by the virus, which has been well studied by researchers. HHMMTV in humans is 90% similar to the mouse virus.The virus was originally discovered to have a link with human breast cancer by the Mount Sinai School of Medicine in New York in 1995. This group and the University of New South Wales team are the only two laboratories working in the area worldwide. Using a technique called in situ PCR, where the breast tissue is taken, stained and viewed on a slide, the Australian group have established that HHMMTV is present in 42% of Australian women who have breast cancer. Interestingly, the virus is only found in the cancerous tissue in the breast, but not in the non-cancerous tissue of the same breast.The work was published in the Journal of Clinical Cancer Research in March 2003. Latest findings of the research were unveiled this week at the Fresh Science forum for young Australian scientists, held annually in Melbourne.In non-cancerous cases, the virus appeared in less than 2% of the samples, and it is not entirely clear that these cases were completely cancer-free. “That was two out of 111 patients, and when we did a follow up this year, both had had breast cancer since the study,” Ford told ABC Science Online. “It’s all evidence that is adding up. It’s not showing it’s causal, but it is a bit too much of a coincidence.”The next step is to establish whether the virus is causing the cancer, or if the cancers provide a good place for the virus to live and multiply. “At this stage we don’t know, it could be either,” she said. “We need to see if it is causing it or if it is there by coincidence.”The team is looking at pre-malignant breast diseases – fibrocystic diseases, or hypoplasia – that increase women’s risk of cancer. “We want to see if we can pick up the virus at an earlier stage,” she said.The discovery means that the virus could be used to identify women with an increased chance of having breast cancer. “It is about 15 years behind human papilloma virus (HPV) [which is used as a marker for cervical cancer],” she said. In the case of HPV there is currently a preventative vaccine, and research is underway to develop a therapeutic vaccine. Ford thinks this could be the future of the HHMMTV. “But that is about 20 years down the track,” she said.Breast cancer affects one in 11 women in Australia, and the disease is the biggest female killer in many Western nations, including the United States and Australia. The World Health Organisation estimates that more than 1.2 million people are diagnosed with breast cancer annually around the world.This virus may also play an important role in male breast cancer, with over 50% of male breast cancer samples testing positive for HHMMTV. A high number of non-cancerous diseases of the breast that are thought to increase the risk for subsequent breast cancer have also been shown to be positive for the virus. (Source: ABC, Danny Kingsley, Wednesday, 20 August 2003)


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Dates

Posted On: 22 August, 2003
Modified On: 5 December, 2013


Created by: myVMC