Epstein-Barr Virus is Associated With Aggressive Subtypes of Invasive Ductal Carcinoma of Breast (Her2+/ER- and Triple Negative) and With Nuclear Expression of NFκB p50

Background: A growing body of evidence suggests a possible role for Epstein- Barr virus (EBV) in the pathogenesis of a subset of breast cancers, with many of these studies highlighting an increased association between EBV and aggressive forms of breast carcinoma. This study aimed to further investigate this issue by assessing the possible association between EBV and the Her2+/ER- and Triple negative sub types of invasive ductal carcinoma (IDC). Methods: An immunohistochemical marker for EBV (Epstein-Barr virus nuclear antigen 1 (EBNA1) clone E1-2.5) was applied to tissue micro array sections. The tissue micro array's contained 58 cases of Her2+/ER- IDC, 57 cases of triple negative IDC and 67 cases of luminal like IDC. Each case was scored as positive or negative for nuclear expression of EBNA1 in tumour cells using standard light microscopy. Clinical and pathological details where noted for each case, as was the nuclear expression of NFκB p50. Results: EBV infection was apparent in 43.2% of all cases. By subtype EBV was evident in 31 (57.4%) Her2+/ER- cases, 28 (49.1%) triple negative cases, and 14 (24.1%) luminal like cases; with a significant association being noted between the Her2+/ER- and triple negative cases and EBV infection (P 0.001). This association was primarily linked with ER negativity, Her2 status showed no significant association with EBV infection. There were no significant associations with other clinical and pathological characteristics. Of the 53 cases demonstrating NFκB p50 nuclear staining, 37 (69.8%) were also infected by EBV (P <0.001). Conclusion: This study provides evidence that EBV is associated with aggressive subtypes of IDC (Her2+/ER- and triple negative) as well as providing evidence for a link between EBV and NFκB p50 nuclear expression, although the nature of these associations remains unclear.