Mouse mammary tumor virus-like gene sequences in breast tumors of Australian and Vietnamese women.

PURPOSE There is considerable evidence that the presence of mouse mammary tumor virus (MMTV)-like gene sequences in human breast cancer is highly associated with human breast carcinoma. Previous studies have found MMTV-like gene sequences in 38% of breast cancer tissue from United States women. The prevalence of these sequences in Australian and Vietnamese women has never been reported. EXPERIMENTAL DESIGN Using PCR and primers that amplify MMTV-like gene sequences, we tested cancerous and benign breast tissue from Caucasian-Australian, Vietnamese-Australian, and Vietnamese women. RESULTS MMTV-like gene sequences were amplified in 19 of 45 (42.2%) archival breast cancer biopsy tissues from Caucasian-Australian women, but only 1 of 120 (0.8%) and 0 of 41 breast cancer biopsy tissues from Vietnamese and Vietnamese-Australian women, respectively. The same sequences were found in only 2 of 111 (1.8%) and 0 of 60 normal (benign) breast tissue samples from Australian and Vietnamese women, respectively. CONCLUSIONS MMTV-like gene sequences are found in only some human populations and are rarely found in normal human breast tissue from all populations, suggesting they are not present in the normal human genome and have been acquired.