Stereotactic body radiation therapy for adrenal metastases: a retrospective review of a noninvasive therapeutic strategy

Abstract

Aims: The role of radiation therapy in the treatment of adrenal metastases has traditionally been a palliative one, achieving excellent pain control with very limited toxicity. Recent studies have focused on the potential role of stereotactic body radiation therapy (SBRT) with curative intent in limited metastatic disease, its potential to reduce tumor burden and to prevent symptomatic progression. This study reports the single-institution outcomes of SBRT utilizing both single fraction and hypofractionated regimens in the treatment of adrenal metastases. Methods: A total of seven patients with nine adrenal metastases treated with SBRT at the University of Pittsburgh Cancer Institute were retrospectively studied. The primary malignancies consisted of non-small-cell lung cancer (n = 4), small-cell lung cancer (n = 1) and hepatocellular carcinoma (n = 2). Results: Five lesions were treated in a single fraction to a median prescription dose of 16 Gy (range: 10–22 Gy) to the 80% isodose line. The remaining four lesions were treated over three fractions to a median prescription dose of 27 Gy (range: 24–36 Gy), with a median prescription isodose line of 94% (range: 80–94%). Median follow-up from the primary diagnosis was 38 months (range: 7–88 months) and from SBRT was 14 months (range: 1–60 months). Follow-up imaging for six patients, and eight metastatic lesions, revealed one complete response, two partial responses and five stable lesions. Five of the lesions eventually failed locally, with a median time to failure of 12 months and actuarial local control of 63% at 1 year. The median overall survival was 8 months from SBRT. Conclusion: SBRT can be safely delivered in single fraction, or hypofractionated, regimens for the treatment of adrenal metastases.