FGFR1 and adenocarcinoma: FGFR1 amplification, defined as a ratio of FGFR1:centromere 8 copy numbers ≥ 2.0, was more frequently seen in squamous cell carcinoma (8.9% of 202 interpretable cases) than in adenocarcinoma (1.6% of 308; p<0.0001).