Increased Detection of Breast Cancer Virus Sequences in Inflammatory Breast Cancer

Earlier studies have suggested an association between breast cancer aggressiveness and the presence of viral sequences resembling mouse mammary tumor virus (MMTV). This study was to determine if inflammatory breast cancer (IBC) in the United States had a higher proportion of cases with these viral sequences than non-IBC patients and if specific risk factors for the sequences could be identified. Biospecimens from 67 patients in the North American IBC Registry were selected for sequencing of MMTV env- like sequences. The presence or absence of the viral sequences was compared to progression free survival (PFS), risk factors including exogenous hormones, and tumor markers. Of the 67 cases, 44 were positive for viral sequences (VSP), 17 were negative (VSN) and six were excluded from analysis because of insufficient DNA to perform replicates. The 72% of VSP cases was significantly more than the 40% in non-IBC U.S. breast cancer patients (p < 0.0001). Non-significant trends suggested that VSP patients were more likely to be HER-2 neu positive and ER negative, have a stronger exposure to exogenous hormones, and have a shorter PFS than VSN patients. MMTV-related sequences appear to be related to the aggressiveness of breast cancer with a higher incidence in North American IBC than in non-IBC breast cancer.