HIF1A and neoplasm: In addition, tumor size > 4 cm (HR = 1.10, 95 % CI 1.00‒1.32, p = 0.012) and HIF-1α with YKL-40 serum level above the cut-off value (HR=1.49, 95 % CI 1.30‒1.91, p = 0.001) were also independent prognostic factors for FTC.