Evaluation of the Effect of Radiosurgery for Target and Non-Target Lesions in Patients with Brain Metastases Using RANO-BM Criteria

The current therapeutic indications of radiosurgery are constantly expanding. Magnetic resonance imaging (MRI) has an important role in the diagnostic and post-therapeutic period of primary and secondary brain tumor formations. A total of 66 patients with verified cancer disease and brain metastases were separated into two groups. The first group includes 34 patients with primary non-small cell lung cancer and the second one 32 patients with other types of primary cancer. All of them received high-dose radiotherapy in 1-5 fractions. The number, size, and location of the treated lesions responded to robotic stereotactic radiosurgery criteria. The Response Assessment Criteria for Brain Metastases (RANO-BM) is an international multidisciplinary group of experts who developed acceptable criteria for assessing brain metastases. Before treatment and on the first, third, sixth month after radiosurgery, a MRI and blood tests were performed. Treated lesions were separated into four groups depending on the results - complete response, partial response, progressive disease, and stable disease. In both groups of patients, the percentage of complete or partial response had increased in the third and sixth months. The results give us a reason not to recommend an MRI 1 month after treatment if the patient doesn't have any new neurological symptoms, because there may be a pseudo-progression. MRI results valued by RANO-BM criteria give us a good option to evaluate brain metastases on the third and sixth month after after stereotactic radiosurgery.