Background:
The viral etiology of breast cancer remains controversial despite substantial evidence linking Epstein-Barr virus (EBV) to the disease.
Material and methods:
We re-analyzed data from two landmark studies (Bonnet et al., 1999; Cox et al., 2010;) using the logical framework of necessary and sufficient conditions, with right-tailed p-values for statistical significance.
Results:
The necessary condition yielded p(EBV ← BC) = 0.9837 (p = 0.0175). The sufficient condition yielded p(EBV → BC) = 0.9769 (p = 0.0308). Both relationships were statistically significant despite design limitations (IOU = 0.4649).
Conclusion:
EBV satisfies both necessary and sufficient conditions for breast cancer, supporting a causal role. The burden of proof now rests with those who would argue otherwise.
Publication Date: 2026-06-21