SAT-176 Epidemiology of Adrenal Tumors: A Population Based Study of 1287 Patients

Background: Adrenal tumors are reported in 5% of adults, with malignancy rates in 1–12%, and rates of overt hormonal excess in 1–15 %. However, most estimates originate from convenience samples. Our objective was to determine the incidence, prevalence and clinical presentation of adrenal tumors in a population-based setting. Methods: We used a centralized epidemiologic database to identify patients diagnosed with adrenal tumors in a local community 1995 to 2017. The database is a unique medical records linkage system that allows access to hospital and community medical records for local residents (population 137,000). We calculated incidence rates (IR) as the number of new patients diagnosed while living in the study area, and prevalence as the number of patients living in the study area on Dec 31 2017. IR and prevalence were sex- and age-adjusted to the 2010 US Census population. Results: Of 1,287 patients diagnosed with adrenal tumor, the median age of diagnosis was 62 years (IQR 52–72), 713 (55%) were women, and 13 (1%) were younger than 18 years at diagnosis. IR was highest in patients >65 YO, followed by patients 40–64 YO, 18–39 YO and <18 YO (142 vs 66 vs 9 vs 2 per 100,000 persons years). IR per 100,000 increased from 4.4 (CI95% 0.3–8.6) in 1995 to 47.8 (CI95% 36.9–58.7) in 2017. Overall prevalence in the population was 0.53% in 2017, ranging from 0.01% among 0–17 YO to 1.9% among +65 YO. Malignant adrenal mass was diagnosed in 8.7% patients (4 patients with adrenal cortical carcinoma (0.3%) and 108 (8.4%) patients with other malignant mass). Pheochromocytoma was diagnosed in 11 (1.1%) patients and benign adrenal mass was diagnosed in 1,175 (90.2%) patients (1,076 (83.6%) with adrenal adenoma and 85 (6.6%) with other benign mass). Median tumor size was 15 mm (range 5–255), and 184 (14%) of patients had bilateral tumors. Only 255 (20%) patients had dexamethasone suppression test, 93 (36%) with cortisol>1.8 mcg/dl. Of 1,076 adrenal adenomas, 53 (4.9%) had overt hormone excess, 140 (13%) had nonfunctioning adrenal adenomas, and 88 (8.2%) had mild autonomous cortisol secretion. Hormonal work up for was incomplete in 795 (73.9%) adenomas. Patients discovered incidentally (1,050, 81.6%) had a lower rate of malignancy and hormone excess (5.3% vs 52% of patients with non-incidental discovery, p <0.001). Rate of malignancy was highest in children (67% vs 8% >18YO, p<0.001), bilateral tumors (16% vs 8% unilateral, p<0.001), tumors ≥4 cm (33% vs 7% in < 4 cm, p<0.001). Conclusion: IR of adrenal tumors increased 10-fold since 1995, and was highest in patients >65 YO. 8.7% of tumors were malignant, with a majority represented by malignant adrenal tumors other than adrenal cortical carcinoma. The risk of malignancy was highest in non-incidental discovery, children, and tumors > 4 cm. Overt hormone excess was diagnosed in 4.5% of patients. The majority of patients with adrenal adenomas had a suboptimal work up for hormone excess.