HER2 Equivocal Status in Early Breast Cancer Is Not Associated with Higher Risk of Recurrence.

Aim: The primary aim of the study was to assess the association between risk of recurrence and HER2 equivocal gene status through immunohistochemistry in patients with early breast cancer.

Patients And Methods: We retrospectively analyzed clinical and pathological data of 455 consecutive patients with early breast cancer (BC) who were HER2(+) and had a HER2/CEP17 ratio <2.0, who underwent surgery at the European Institute of Oncology after 2007. The role of HER2/CEP17 ratio on recurrence-free survival was assessed with univariate and multivariate Cox regression models.

Results: We found no significant association between risk of recurrence and HER2 equivocal testing in patients with early breast cancer. In subgroup analysis, a significant interaction between HER2/CEP17 ratio and nodal involvement was observed (p=0.02).

Conclusion: Patients with HER2 equivocal status have no significantly higher risk of recurrence.