Several risk factors are independent predictors of a more aggressive behavior from the first diagnostic or of a poor response to standard therapy, for instance, large, invasive tumors have a lower rate of remission after hypophysectomy; a partial response to first line SSAs (octreotide and lanreotide) is expected in cases with sparsely granulated adenomas, lack of somatostatin receptor type 2 (SSTR2) at immunohistochemistry report, very young patients, particular imaging aspects such as T2-hyperintensity, and mutations of the AIP gene (aryl hydrocarbon receptor-interacting protein) [64,65]. This evidence concerns the gene AIP and adenoma.