New virus linked to breast cancer

Researchers at the Prince of Wales Hospital have established a link between breast cancer and the human form of a mouse virus.

The research, in progress since 2000 in association with the University of NSW, has identified the human homologue of mouse mammary tumour virus (HHMMTV) as being present in over 40 per cent of cancerous breast tissue.

The leader of the research group, Dr Margaret Faedo, said the incidence of HHMMTV in cancerous tissue was way above its incidence in normal tissue; about 2 per cent on average.

"The rate varies in different breast diseases, and we have used PCR to screen gynecomastia, fibroadenoma, fibrocystic disease and hyperplasia for the envelope region of MMTV. Our studies show that the prevalence in pre-malignant tissue is approximately 22 per cent, and in malignant tissue is over 40 per cent," she said.

Faedo said the initial studies showed that the more sever the cancer, the higher the incidence of the virus. She said that cancerous cells showed much more positive staining than any surrounding non-cancerous cells.

UNSW PhD student and Fresh Science winner Caroline Ford, one of the researchers on the project, noted the virus could also be linked to the relatively rare male breast cancer, with over fifty percent of male breast cancer samples tested positive for HHMMTV.

"Many people believe that breast cancer is purely a hereditary disease, yet... we have little idea what causes 19 out of 20 cases of breast cancer. These results indicate that a virus may be involved," said Ford.

"This research puts the virus at the scene of the crime, but we have not yet established a causal link," she warned.

However, Faedo is optimistic about the outcome of the research. "There is no doubt this virus has a lot of potential for causation. We now have to do more mechanistic studies to see what it is doing, how it is integrating," she said.

"If these turn out well, and we establish a link and a role for HHMMTV in breast cancer, we would certainly look at developing either a vaccine or an anti-viral," she added.