Medical treatment of acromegaly – When the tumor size matters: A narrative review

Medical treatment of acromegaly is generally positioned as a second line of treatment after pituitary adenoma surgery. With the rising availability and variety of medications for acromegaly increases our understanding of their effectiveness and safety. Volume of the published data on the impact of medical therapy on biochemical control of acromegaly, contrasts a relative lack of publications which comprehensively address pituitary tumor alterations under different drug modalities. Assessment of changes in GH-secreting adenoma volume is often overshadowed by clinicians' focus on GH and IGF-I levels during acromegaly treatment. Close analysis of studies published in the last two decades, reveals that both an increase and decrease in somatotropinoma volume are possible during treatment with any of available drugs for acromegaly. Changes in pituitary tumor size may arise from the biological nature of adenoma itself, independently of the administered medications. Therefore, an individual approach is necessary in the treatment of patients with acromegaly, based on repeated insight to their clinical, biochemical, pathological and imaging characteristics. In this review, we summarize and comment how pituitary tumor size is affected by the treatment with all currently available drugs in acromegaly: long-acting somatostatin receptor ligands of the first generation (octreotide LAR and lanreotide autogel) and the second generation (pasireotide-LAR), as well as pegvisomant (PEG) and cabergoline (CAB).