Endocrine Abstracts

Background: Data on outcomes of ACC ≤ 4 cm are scarce.

Objectives: To characterize presentation and outcomes of patients with ACC ≤ 4 cm.

Methods: Single-center cohort study of adults with ACC ≤ 4 cm, 2000-2024. Outcomes included overall survival (OS) and disease-free survival (DFS).

Results: In 32 patients (75% women) ACC was diagnosed at a median age of 61 years (range 21-83). ACC diagnosis (T0) was determined by the histopathology from adrenalectomy in 21 (65%), biopsy in 8 (25%), and presence of hormone excess in 3 (9%) patients with metastases. Following the earliest imaging that demonstrated a median adrenal mass size of 27 mm (range 9-40) and median unenhanced Hounsfield unit measurement of 31 (range 18-50), ACC was initially suspected in 15 (47%) patients. In 23 patients with at least two imaging studies 6 weeks apart prior to T0, median adrenal mass growth rate was 17 mm/year (range 0-57). Hormone excess was diagnosed in 22 (69%) patients: hypercortisolism in 11 (34%), hyperandrogenism in 4 (13%), mineralocorticoid excess in 4 (13%), and combined hypercortisolism and hyperandrogenism in 3 (9%) patients. Adrenalectomy was performed in 29 (91%) patients: laparoscopic in 20 (69%) and open in 9 (31%), with R0 resection documented in 25 (86%), R1 in 2 (7%), and Rx in 2 (7%) patients. Median tumor size at adrenalectomy was 37 mm (range 12-270). Oncocytic ACC was reported in 7 (24%), myxoid in 1 (3%), and oncocytic/myxoid in 1 (3%) patient. Median Ki-67 (n =16) was 10% (range 2-51). At T0, staging was ENSAT stage I in 15 (46%), stage II in 4 (13%), stage III in 9 (28%), and stage IV in 4 (13%) patients. Patients were treated with mitotane (18, 56%), chemotherapy, immunotherapy and/or tyrosine kinase inhibitors (11,34%), and radiation (8, 25%). Patients were followed for a median of 3 years (range 0.06-20) post T0. In 28 (88%) patients with non-metastatic disease prior to adrenalectomy, metastases occurred in 10 (36%) at a median time of 0.9 years (range 0.2-3). Five-year OS was 63% and DFS was 56%.

Discussion/Conclusion: We demonstrate several factors associated with worse prognosis in patients with ACC ≤4 cm, including pre-operative biopsy, laparoscopic adrenalectomy, and Ki-67 >10%. A large multicenter study to understand gaps in diagnosis and treatment of ACC ≤4 cm is currently underway.