Lower FDG PET/CТ SUV max shows better response to SBRT of adrenals in oligometastatic disease
PO-1474
Abstract
Lower FDG PET/CТ SUV max shows better response to SBRT of adrenals in oligometastatic disease
Authors: Kiril Zhelev1, Dimitar Katsarov2, Nedyalka Velikova3, Zahari Zahariev4, Iglika Mihaylova2, Nikolay Nedev3, Rositsa Krasteva5, Rosen Hadgiev6, Nikolay Conev7, Ivan Donev8
1MHAT Uni Hospital, Department of Radiotherapy, Panagyurishte, Bulgaria; 2SHAT in Oncology Sofia, Department of Radiotherapy, Sofia, Bulgaria; 3UMHAT Acibadem City Clinic, Department of Radiotherapy, Sofia, Bulgaria; 4MHAT Uni Hospital, Deprtment of Radiotherapy, Panagyurishte, Bulgaria; 5MHAT Uni Hospital, Department of Oncology, Panagyurishte, Bulgaria; 6UMHAT Lozenetz, Department of Forensic Medicine , Sofia, Bulgaria; 7UMHAT St Marina, Department of Oncology, Varna, Bulgaria; 8MHAT Nadezhda, Department of Oncology, Sofia, Bulgaria
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Purpose or Objective
Stereotactic body radiotherapy (SBRT), as ablative and noninvasive treatment was well established for oligometastatic disease (1 to 3 metastatic lesions) and became increasingly used to manage cancer with adrenal gland metastases. The aim of this multicentric study was to evaluate the safety and efficacy of SBRT in patients with oligometastatic disease in adrenal glands.
Material and Methods
In this retrospective study, we performed an analysis of 75 metastatic adrenal lesions in 64 patients, where 36 (48%) non - small cell lung cancer (NSCLC), 18 (24%) small cell lung cancer (SCLC), 10 (13.3%) rectal cancer and other 11 (14.6%) (such as breast and renal cancer) oligometastatic disease, treated from 2015 to 2020, aiming to achieve durable local control. All patients progressed mainly with increasing adrenal masses area (other lesions were under control). Patients were divided into three groups according to their fluorodeoxyglucose positron emission tomography (FDG PET/CТ) SUV max of adrenal metastasis – with low (up to 33th percentile, range: 3.9-7.20), intermediate (between 33th and 66th percentile, range: 7.21-9.31) and high SUV max (over 66th percentile, range: 9.31-25.8). Overall response rate (ORR), is the proportion of patients who had a partial or complete response to the treatment. The main dose regimens were 38 Gy delivered in 1– 5 fractions, with the median dose of primary tumor volume (PTV) being 38 Gy (range: 16–48 Gy) and the biologically effective dose (BED10, alpha/beta = 10) being 79.2 Gy (range: 41.6–105.6 Gy).
Results
The cohort included 34 men (53.1%) and 30 women (46.9%), with a total mean age of 65.5 ±8.9 years. ORR was 40%. Between all clinicopathological characteristic such as gender, age, histology, time to progression etc. we found no significant relationship except for levels of SUV max and ORR (Kendall Tau-c=0.29; p=0.017). Patients who responded to SBRT had a significantly lower SUV max value, than those who did not respond (7.6±2.4 vs 9.7±3.8; p=0.015). At the optimal cut-off values for SUV max, the biomarker could significantly and moderately distinguish between patients with or without response (AUC = 0.67, 95% confidence interval (CI) = 0.54–0.79; p = 0.015), with a sensitivity of 63.5% and a specificity of 60.1%. Moreover, in multiple binary logistic regression, lower levels of SUV max is associated with good response to radiotherapy (OR 0.27 95% CI: 0.07-0.97; p=0.049).
Conclusion
Lower SUV max is associated with better response to SBRT in patients whose disease progressed mainly in adrenal glands.