Kim et al. investigated 526 curatively resected ESCC using FISH for FGFR1 amplification and found that an association between high FGFR1 amplification (defined as an FGFR1/centromer 8 ratio ≥ 2.0, or average number of FGFR1 signals/tumor cell nucleus ≥ 6.0, or percentage of tumor cells containing ≥ 15 FGFR1 signals or large cluster in ≥ 10% with significantly shorter disease-free survival (DFS) and OS [15]. Here, FGFR1 is linked to esophageal squamous cell carcinoma.