Characteristics of Adrenal Incidentalomas in a Large, Prospective Computed Tomography-Based Multicenter Study: The COAR Study in Korea

Purpose: Previous studies on adrenal incidentalomas (AIs) are limited by their retrospective design, small numbers of patients, Western populations, or use of an outdated imaging technique. We investigated the characteristics of Als in Korean patients and compared them with those reported in the largest retrospective study in Italy to discover the effects of improved imaging techniques and ethnicity differences. Materials and Methods: This was a prospective, multicenter, cross-sectional observational study including 1005 Korean patients. Levels of plasma adrenocorticotrophic hormone, 24-h urinary free cortisol (UPC), serum cortisol after a 1 mg-dexamethasone suppression test, 24-h urinary fractionated metanephrine, and plasma aldosterone and plasma renin activity were measured. All Ms were characterized using computed tomography (CT). Results: Compared with the results of the Italian study, Als in Korean patients were observed more frequently in men and predominantly on the left side. Korean patients with AIs were slightly younger, and fewer patients underwent surgery. Most Ms were nonfunctional in both studies, while fewer subclinical hypercortisol ism and more primary aldosteronism (PA) cases were detected in Korean patients. In our study, high UFC levels showed very low sensitivity, compared to those in the Italian study. In pheo-chromocytoma or PA cases, there were no hormonal differences between the studies. Ms in Korean patients were smaller, such that a lower cutoff size for detecting adrenocortical carcinoma (ACC) could be warranted. Conclusion: Recent advances in CT technology were leveraged to provide accurate characteristics of AIs and to detect smaller ACCs.