Patients with acromegaly have high incidence of benign or malignant neoplasia than general population. Around fifteen percent of the deaths reported in acromegaly are attributable to malignancy of cancer. On the whole, mortality in acromegaly has been shown to be correlated with the degree of growth hormone (GH) control. Especially, the levels of insulin like growth factor-1 (IGF-1) may be higher in neoplasm, but there is no clear evidence to prove that tumor development is triggered by IGF-1 in acromegaly.