Mouse Virus Linked to Breast Cancer
Research Suggests Virus Spreads from Person to Person
Dec. 14, 2006 (San Antonio) -- A virus that infects the common house mouse
may cause more than one in three cases of breast cancer in
the U.S., researchers report.
In Asia, however, the virus plays a very small role in causing the disease,
says James F. Holland, MD, distinguished professor of neoplastic diseases at
Mt. Sinai School of Medicine in New York.
"The human breast cancer virus may explain
why breast cancer rates differ throughout the world," he tells WebMD.
Holland reviewed recent research on the breast cancer virus at the San
Antonio Breast Cancer Symposium.
How Breast Cancer Virus Spreads
Holland says the virus does not appear to be inherited from one's parents.
Rather it is spread from person to person, like the common cold.
That conclusion came from a study of more than 200 women with breast cancer.
Researchers detected the virus in about 30% of tissue samples from their
affected breast, but in only one sample of normal tissue from the unaffected
"If it was genetically transmitted, the virus would be present in both
tissue samples," Holland explains.
Michael Dosik, MD, a breast cancer specialist at Stony Brook University in
Stony Brook, NY, says that "while interesting, there's still a long way to
"While the virus seems to be spread from person to person -- not
genetically -- we need to figure out exactly how it is transmitted," he
Holland agrees. "It could be spread by sneezing or perhaps eating
infected food, for example. We're testing many theories."
Viruses and Breast Cancer
Viruses are known to be involved in the development of several cancers,
including cervical cancer;
previous studies suggested that a virus similar to the mouse mammary tumor
virus (MMTV) is associated with breast cancer in humans.
Holland says that other new research suggests that the human breast cancer
virus is "a kissing cousin" of MMTV, "most likely caused by a
mutation that occurred thousands of years ago."
Other new work suggests that variations in breast cancer prevalence
worldwide can be explained by the fact that the species of house mouse that
carries that virus is more common in certain regions, he says.
In North America, Europe, and Australia, where the species is common, the
virus was detected in 30% to 40% of breast cancer tissue samples, he says.
In Asia, where the species in rare, the picture is quite different. In
Japan, only 12% of samples were infected. In Vietnam, less than 1% of samples
In that study, researchers tested 524 tissue samples from women treated for
breast cancer in the U.S. and compared the results with breast cancer tumor
samples from women treated for breast cancer in other countries.