Fresh Science

Some cases of breast cancer may be caused by a virus according to new research by scientists at the University of New South Wales and Prince of Wales Hospital.

“More than 40 percent of Australian breast cancer samples have the virus, while it is only found in  two percent of normal breast tissue samples (taken from cosmetic surgery) ,” says Caroline Ford, a University of New South Wales PhD student and Fresh Science winner.

“If this virus does in fact play a role it opens up the possibility of a preventative vaccine,” says Caroline. “However we have to do much more work to prove the link.”

Breast cancer is the most common cancer of Australian women, affecting 1 in 11 women.

While many risk factors have been identified, no clear causes of breast cancer have been defined.  The new virus, known as HHMMTV, is the human homologue of mouse mammary tumour virus which causes more than 95% of breast cancer in mice.

Caroline’s research was conducted in with researchers from the Prince of Wales Hospital and published in the Journal of Clinical Cancer Research. Not only does the study demonstrate a strong link between this virus and breast cancer, it also suggests an association between the virus and more severe forms of breast cancer. The virus is usually only found in the cancerous and not in the normal breast tissue from women with breast cancer.

This virus may also play an important role in male breast cancer, with over fifty percent 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.

“Many people believe that breast cancer is purely a hereditary disease, yet hereditary breast cancer is estimated to account for only 5% of all cases of breast cancer. In other words, we have little idea what causes 19 out of 20 cases. Our preliminary research indicates that a virus may be involved,” Ms Ford says.

This new research supports the link between this virus and breast cancer in Australia. If it can be shown that this virus causes cancer, the possibility of a preventative vaccine for breast cancer would be of enormous consequence.

“It’s an exciting discovery, but there’s a lot of work still to do to get sufficient proof of the role of the virus,” says Caroline.

Caroline is presenting her research to the public for the first time thanks to Fresh Science, a national program to bring public attention to the remarkable unsung achievements of young Australian scientists. She will be speaking to the public and school students about her work on Tuesday 19 and Wednesday 20 August at the Melbourne Museum.

Caroline FordPhD student University of New South Wales

Could breast cancer be caused by a virus?

Breast cancer and the role of viruses

Breast cancer is an extremely common disease, yet no clear cause has yet been determined. In recent years many cancers have been linked to infection with different viruses. We have investigated the possibility that some cases of breast cancer may be caused by a  virus termed HHMMTV, or the human homologue of mouse mammary tumour virus.

Project description

Breast cancer is the most common cancer of Australian women, affecting 1 in 11 women. While many risk factors have been identified, no clear cause of breast cancer has been defined. Many people believe that breast cancer is purely a hereditary disease, yet hereditary breast cancer has been estimated to account for only 5% of all cases of breast cancer. In other words, we have little idea what causes 19 out of 20 cases of breast cancer.

In recent years many other cancers have been linked to viruses, most notably cervical cancer and human papilloma virus, or HPV. We believe that breast cancer is caused by multiple factors, including hormonal, genetic and environmental factors. We have focused our research on the role of one environmental agent, a virus termed HHMMTV, as a possible cause of breast cancer.

HHMMTV stands for the human homologue of mouse mammary tumour virus, and as the name implies is a human form of MMTV, which causes >95% of breast cancer in mice.

Our research group situated at the Prince of Wales Hospital, undertook a study in 2000 to determine how common this virus is in the Australian population. We showed for the first time that this virus plays an important role in breast cancer cases in Australia by demonstrating a strong link between this virus and breast cancer in the Australian population.

Forty-two percent of Australian breast cancer samples tested were positive for the virus, while only two percent of normal breast tissue samples (taken from cosmetic surgery) were positive.  Further studies by our group have shown that this virus appears to be associated with more severe forms of breast cancer, and is only found in cancerous and not in normal breast tissue from women with breast cancer. We have also recently shown for the first time that this virus may play an important role in male breast cancer, with over fifty percent of male breast cancer samples tested positive for HHMMTV. A high number of non cancerous diseases of the breast that are thought to increase a persons risk for subsequent breast cancer, have also been shown to be positive for this virus.

These studies support the role of this virus in breast cancer in Australia. If it can be shown that this virus causes cancer, the possibility of a preventative vaccine for breast cancer would be of enormous consequence.

Personal details

Qualifications: BSc (Class 1 Honours) UNSW 2000, PhD 2001 – UNSW ongoing Virology Research Laboratory, Department of Microbiology, SEALS, Prince of Wales Hospital Virology Research Laboratory, Department of Microbiology, SEALS, Prince of Wales Hospital.