MMP-9 expression was higher in the patients with invasive pituitary adenomas (IPAs) than patients with noninvasive pituitary adenomas (NIPAs) with detection methods of IHC [odds ratio (OR) = 5.48, 95% confidence interval (CI) = 2.61–11.50, P < 0.00001), and reverse transcriptase-polymerase chain reaction (SMD = 2.28, 95% CI = 0.91–3.64, P = 0.001). The gene discussed is MMP9; the disease is pituitary gland adenoma.