P.J. Abraham1, M.N. Abraham1, R. Wang1, A. Gillis1, J. Fazendin1, B. Lindeman1, H. Chen1 1University Of Alabama at Birmingham, Department Of Surgery, Birmingham, AL, USA
Introduction: Adrenalectomy is recommended for tumors ≥ 4cm based on concern for malignant potential. Prior studies have shown a malignancy rate of 5-10% for tumors of this size. For adrenal tumors <4cm, the recent American Association of Endocrine Surgeons (AAES) Guidelines for Adrenalectomy quotes a <0.5% primary malignancy rate, which suggests that these tumors (if nonfunctional) may be managed nonoperatively. This study examines malignancy rates for a large, retrospective cohort of adrenal tumors at one institution.
Methods: An institutional database of 538 patients who underwent adrenalectomy from October 2012 – November 2023 was reviewed. Multiple clinical factors including the reason for surgery, tumor size based on preoperative imaging, and final pathology were extracted for all cases. Malignancy rates were compared using varying tumor size cutoffs ranging from 2-4cm.
Results: We included 495 patients in this study after excluding pheochromocytomas, cases with indeterminate malignancy on pathology, and cases in which the adrenal gland was removed due to local invasion from an extra-adrenal malignancy. Malignancy was noted on final pathology for 65 patients, with 15 adrenocortical carcinomas (ACC) and 50 cases of metastasis. Nearly half (49.2%, n=32) of the malignant tumors were <4cm. For nonfunctional tumors, 23.1% (n=51) were malignant, with nearly half (47.1%, n=24) of those being <4cm. For ACCs, 26.7% (n=4) were <4cm based on preoperative imaging. The malignancy rate remained significantly (p<0.05) higher for the larger tumor size group when size cutoffs of 4cm, 3.5cm, 3cm, and 2.5cm were employed.
Conclusion: Although current guidelines suggest 4cm as the size cutoff for considering an adrenal tumor to have significant malignant potential, our data show that many patients at our institution with adrenal tumors <4cm had a cancer diagnosis on final pathology. The dogma of a 4cm cutoff may need to be revisited and additional imaging characteristics should be taken into account when considering adrenalectomy.