Background: Craniopharyngioma is a benign tumor, but recurrences are common and prognosis is poor. The pathologic mechanism underlying the high recurrence is still unknown.

Objective: We hypothesized that there are hypoxic microenvironments within craniopharyngiomas and hypoxia inducible factor-1 alpha (HIF-1α) and its related genes are largely expressed in recurrent craniopharyngiomas.

Methods: A total of 19 patients with craniopharyngiomas have been identified. The relative quantitative expressions of HIF-1α, vascular endothelial growth factor (VEGF) and carbonic adhydrase 9 (CA9) messenger ribonucleic acid (mRNA) of craniopharyngioma tissues were detected by real time reverse transcription polymerase chain reaction.

Results: HIF-1α and VEGF mRNA was significantly up-regulated in recurrent craniopharyngiomas. Mean expression levels (recurrent craniopharyngiomas compared with non-recurrent craniopharyngiomas, as normalized to expression of β-actin) were 3.09 versus 0.75 (P = 0.001) for HIF-1α, 1.07 versus 0.32 (P = 0.000) for VEGF, 1.21 versus 1.93 (P = 0.503) for CA9. In craniopharyngiomas, the expression of VEGF showed a significant correlation with HIF-1α (r = 0.836, P = 0.000).

Conclusions: There were hypoxic microenvironments within craniopharyngiomas. Therefore, preventing the tumor cells from adapting to the hypoxic conditions may be an effective way to obviate the relapse of craniopharyngioma.