PSUN26 Radiation For Adrenal Metastases: Should Patients be Monitored For Primary Adrenal Insufficiency?

BACKGROUND: Adrenal metastasis is the most common adrenal malignancy and can be bilateral in up to 43% of patients. Risk of primary adrenal insufficiency (PAI) in bilateral metastases is 12%. Adrenal radiation is one of the options available to treat adrenal metastases. The risk of PAI after bilateral adrenal radiation is unclear. OBJECTIVE: We aimed to determine the incidence and the timeline of PAI in patients undergoing adrenal radiation for bilateral metastases. Design, Setting, and Participants: Single center retrospective study of adult patients with adrenal metastases treated with adrenal radiation between 2010 and 2021. RESULTS: Of 55 patients with adrenal metastases treated with adrenal radiation, 7 (12.7%) had bilateral therapy, of whom 5 (all with lung adenocarcinoma) developed PAI. Another patient with history of unilateral adrenal radiation and previous contralateral adrenalectomy also developed PAI. Following the radiation therapy (median dose 50 Gy [range 20-65 Gy]), administered in a median of 5 fractions (range 5-18 fractions) in 6 patients who developed PAI, all treated metastases either decreased in size during imaging follow up or demonstrated a decrease in SUV uptake on PET scan. PAI developed at a median time of 6.1 months after radiation (range 0.5-20.4 months). PAI was diagnosed based on laboratory monitoring in 3 patients and based on treating endocrinologist's discretion (e.g., symptoms, clinical context) in the other 3 patients. Patients were initiated on hydrocortisone (median daily dose of 20 mg, range 15-80 mg) and fludrocortisone (median dose of 0.05 mg, range 0.05-0.1 mg) At the end of the study period, daily replacement dose was higher for both for hydrocortisone (median of 35 mg, range 15-160 mg) and for fludrocortisone (median of 0.0625 mg, range 0.05-0.1 mg). All but one patient with PAI had passed away at the end of the study, at a median time of 19.7 months (range 6.1-55.8 months) since radiation and median time of 7.7 months (range 1.2-55.3 months) since the diagnosis of PAI. In the two patients with bilateral adrenal radiation who did not develop PAI, the follow up was short: 1 patient passed away six-months post-radiation and another patient had only 4 months of follow up. CONCLUSION: Adrenal radiation is an effective therapy for patients with adrenal metastases. Risk of PAI is very high when bilateral adrenal radiation is administered, and patients need to be counseled about it. We observed that daily glucocorticoid replacement dose was excessive in some patients possibly reflecting the use of stress dosing due to underlying sickness. Both clinical and biochemical monitoring every 3-6 months should be instituted in patients undergoing bilateral adrenal radiation. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.