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.