Fig 1: Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) of cases with CCNE1 copy number gain. All cases with CCNE1 copy number gain were tested for and confirmed positive by both CCNE1 FISH (A, ×1000) and IHC (B, ×200). Significantly higher CCNE1 gene amplification by FISH CCNE1/CEP19 ratio (C) and Cyclin E protein expression (D) were observed in patients who did not progress before 6 months than those who did (p = 0.050 and 0.016, respectively). The CCNE1 FISH ratio and IHC showed good positive correlation (r = 0.68, p < 0.001). (E) p‐value by Mann–Whitney test and Fisher‐exact test. Correlation coefficient rho (R) by Spearman rank correlation. Mo, months.