**8. Statistical analysis**

All statistical analyses were performed with SPSS software v12.0. The Chi-square (χ2 ) was used to assess the relationship between HIF-1α and degree of histological malignancy and clinical staging. The Fisher exact test was used when the expected cell counts were less than 5. The results were considered as statistically significant if the *p* value was less than 0.05 (*p* < 0.05).
