Third, although an increased risk of thyroid cancer in acromegaly has been published [226], this condition implies a very high and sustained release of GH for many years, and, therefore, we cannot be sure of the fact that it is GH and no other factors (for example, IGF-I) responsible for the slight increase in prevalence of cancer in patients with acromegaly. This evidence concerns the gene GH1 and acromegaly.