The Modern Criteria for Medical Management of Acromegaly

Abstract

Acromegaly is an insidious disorder characterized by excess secretion of growth hormone (GH) and elevated circulating levels of insulin-like growth factor-I (IGF-I), generally caused by a pituitary adenoma. It is a rare disease associated with an average 10-year reduction in life expectancy due to metabolic, cardiovascular, and cerebrovascular comorbidities and reduced quality of life caused by paresthesias, fatigue, osteoarthralgia, or bone fractures. In 2000, Cortina Consensus Conference established general criteria for diagnosis and biochemical control of acromegaly, which have been revised in recent years, adapting them to emerging clinical evidences as well as the evolving assay techniques. Authors have proposed a binary definition of cure for acromegaly, where both GH and IGF-I are important determinants: the former is more linked to the presence of residual adenomatous tissue, while the latter to the peripheral activity of the disease. Control of tumor growth and complications is also an essential goal of treatment. Surgical, medical, and radiotherapy approaches are all valid alternatives. The surgical option is, however, unsuccessful in about 50% of patients. Somatostatin analogs (SRLs), octreotide LAR, and lanreotide ATG can inhibit cell growth, besides their beneficial effects on GH hypersecretion and on most comorbidities. Pasireotide is a new multireceptor-targeted SRL with reported superior biochemical efficacy to octreotide, due to higher affinity for SSTR-5, but potentially causing detrimental effects on glucose homeostasis. Pegvisomant could be a valid choice in all patients resistant to SRLs. It is a competitive GH antagonist, which efficaciously blocks IGF-I production, inhibiting the dimerization of GH receptor. Normal IGF-I levels represent, therefore, its only relevant efficacy endpoint, while only few cases of tumor growth on pegvisomant have been reported, so far.

Keywords: acromegaly; guidelines; medical therapy; pegvisomant; somatostatin analogs.