MET-14 OUTCOME OF METASTATIC CEREBELLAR TUMOR: A SINGLE-CENTER STUDY


 
 
 Brain metastases (BM) to the cerebellum account for approximately 20% of all of BM. From the results of JCOG0504 clinical trial, observation with salvage SRS (stereotactic radiosurgery) has been established as a standard therapy for a patient after complete resection of BM. However, we often experience early local recurrence after resection of cerebellar BM, therefore, we retrospectively analyzed them to consider the appropriate timing of SRS.
 
 
 
 We extracted surgical cases with cerebellar BM from January 2015 to March 2022 and analyzed the patient characteristics, treatment content, postoperative intracranial progression-free survival (IC-PFS) and postoperative overall survival (OS).
 
 
 
 A total of 57 cases were enrolled (male: female = 43.9%: 56.1%) in this study. The median age was 61.9 years (51.9-68.2). The common primary lesions were NSCLC (31.6%), colorectal cancer (19.3%), and breast cancer (17.5%). The IC-PFS was 4.5 months (2.6-5.7) and the OS was 11.6 months (9.1-21.8), but the local recurrent rate within 3 months was 43.4%. The rate of patients with leptomeningeal metastases (LMM) at the first recurrence was 26.3%, significantly higher than 7.7% in JCOG0504 (p=0.000224). In the postoperative observation group (no SRS within a month), the OS was 25.3 months (11.6-NA), which was longer than the 15.6 months (11.4-20.8) of JCOG0504. RT was performed in 18 patients at the recurrence (SRS: 15, WBRT (whole-brain radiotherapy): 9). SRS was the only factor that prolonged the OS (25.2 vs. 6.1 months (p=0.0212)). Furthermore, in the patients who underwent radiotherapy within 1 month after surgery, postoperative SRS (10.2 vs. 3.1 months, p=0.00437), and postoperative SRS to the resection cavity (11.0 vs. 3.7mo, p=0.0012) significantly prolonged the OS.
 
 
 
 Since cerebellar BM has high recurrence and frequent LMM, early SRS for a resected cavity after surgery might lead to more favorable outcomes in cerebellar BM patients.
