Tumours were classified according to size (microadenoma, macroadenoma and giant pituitary adenomas), type (Prolactin, Growth Hormone, FSH/LH, ACTH and TSH) and grade (grade 1a: non-invasive, 1b: non-invasive and proliferative, 2a: invasive, 2b: invasive and proliferative, and 3: metastatic). This evidence concerns the gene GH1 and neoplasm.