Virus Linked to Aggressive Breast Cancers

Although viruses are known to play a primary role in the development of several human cancers, such as the T cell lymphotropic virus and adult T cell leukemia/lymphoma or herpes virus 8 (HHV8) and Kaposi sarcoma (KS), geographic variability has been noted. For example, KS and HHV8 are least common in the United States and more common in the Mediterranean and Central African regions.

Previous analyses of human breast tissue found viral sequences from the mouse mammary tumor virus (MMTV) in a large percentage of breast cancers but not in normal tissue. MMTV may be spread by a species of house mouse very common in North Africa but not in the United States.

Researchers compared 38 breast tumors from Tunisian patients with samples from several other countries. A significantly higher proportion of samples from Tunisia tested positive for an MMTV-specific genetic sequence, compared to samples from North America. While 74% of Tunisian samples tested positive, other studies reported only 36% from the United States, 38% from Italy, 42% from Australia, and 31% from Argentina. Further analyses revealed that 89% of the MMTV-positive samples were from clinically and histologically aggressive tumors.

"These findings provide increasing evidence for a human breast cancer virus with geographic differences in prevalence,” concluded the authors. The study was conducted by Dr. Paul H. Levine from the George Washington University School of Public Health and Health Services (Washington, DC, USA; www.gwumc.edu) and his colleagues.





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George Washington Univ. School of Public Health