Interobserver Variation in the Assessment of Immunohistochemistry Expression Levels in HER2-Negative Breast Cancer: Can We Improve the Identification of Low Levels of HER2 Expression by Adjusting the Criteria? An International Interobserver Study

Ximena Baez‐Navarro, Mieke Van Bockstal, Diënna Nawawi, Glenn Broeckx, Cécile Colpaert, Shusma C. Doebar, M. C. H. Hogenes, Esther A. Koop, Kathleen Lambein, Dieter Peeters, Renata H.J.A. Sinke, Johannes Bastiaan van Brakel, José van der Starre-Gaal, Bert van der Vegt, Koen Van de Vijver, Celien P.H. Vreuls, Willem Vreuls, Pieter J. Westenend, Carolien H. M. van Deurzen