Lower fluorodeoxyglucose positron emission tomography maximum standardized uptake value may show a better response to stereotactic body radiotherapy of adrenals in oligometastatic disease

Introduction Stereotactic body radiotherapy (SBRT) is well established for oligometastatic disease, and it is increasingly used to treat adrenal metastases. Material and methods In this retrospective study we performed an analysis of 75 metastatic adrenal lesions in 64 patients with oligometastatic disease. According to the fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) maximum standardized uptake value (SUVmax) of adrenal metastases, patients were categorized into three groups: low, intermediate, and high SUVmax. Results For all clinicopathological characteristics we found significant relationships for levels of SUVmax and objective response rate (Kendall Tau-c = 0.290; p = 0.017). Patients who responded to SBRT had a significantly lower SUVmax value than those who did not respond (7.6 ±2.4 vs. 9.7 ±3.8; p = 0.015). At the appropriate SUVmax cut-off values, the biomarker distinguished between patients with and without a response significantly and moderately (area under the curve = 0.670, 95% confidence intervals: 0.540–0.790; p = 0.015). Conclusions Lower SUVmax is associated with a better response to SBRT in patients whose disease progressed mainly in the adrenal glands.