Development of a prediction model by combining tumor diameter and clinical parameters of adrenal incidentaloma

When adrenal incidentalomas are detected, diagnostic procedures are complicated by the need for endocrine-stimulating tests and imaging using various modalities to evaluate whether the tumor is a hormone-producing adrenal tumor. This study aimed to develop a machine-learning-based clinical model that combines computed tomography (CT) imaging and clinical parameters for adrenal tumor classification. This was a retrospective cohort study involving 162 patients who underwent hormone testing for adrenal incidentalomas at our institution. Nominal logistic regression analysis was used to identify the predictive factors for hormone-producing adrenal tumors, and three random forest classification models were developed using clinical and imaging parameters. The study included 55 patients with non-functioning adrenal tumors (NFAT), 44 with primary aldosteronism (PA), 22 with mild autonomous cortisol secretion (MACS), 18 with Cushing's syndrome (CS), and 23 with pheochromocytoma (Pheo). A random forest classification model combining the adrenal tumor diameter on CT, early morning hormone measurements, and several clinical parameters was constructed, and showed high diagnostic accuracy for PA, Pheo, and CS (area under the curve: 0.88, 0.85, and 0.80, respectively). However, sufficient diagnostic accuracy has not yet been achieved for MACS. This model provides a noninvasive and efficient tool for adrenal tumor classification, potentially reducing the need for additional hormonal stimulation tests. However, further validation studies are required to confirm the clinical utility of this method.