P11.55.B Postoperative MRI is able to detect an unexpected residual tumor after surgery of brain metastases: experience from 5 specialized centers. (5th September 2022) - Kiesel, B
Abstract: Background: Brain metastases (BM) constitute the most common central nervous system tumors. The treatment options of BM consist of surgery, radiotherapy, radiosurgery, chemotherapy, and immunotherapy. Regarding surgery in BM, the extent of resection (EOR) represents a crucial factor for patient prognosis. However, first studies using postoperative MRI demonstrated that an unexpected residual tumor after surgery of BM is not uncommon despite these tumors were considered to be well-demarcated. The aim of this study was thus to investigate in a large cohort including multiple neurosurgical centers the EOR following BM resection, potential risk factors for incomplete resection and postsurgical follow-up data. Material and Methods: In the current retrospective study conducted at 5 specialized neurosurgical centers in Austria, we included patients with BM resection and available postoperative MRI. The EOR following BM resection was determined by postoperative MRI (complete vs incomplete resection). Additionally, the data on the intraoperative judgement of the EOR of the performing neurosurgeon were collected. Moreover, potential factors for incomplete resection including tumor localization, tumor volume, primary tumor, pattern of contrast media enhancement on imaging and tumor eloquence were investigated. Finally, the rate of local progression of BM after initial surgery was analyzed in the follow-up period and overall survival data were collected. Results: Altogether, 548 patients with 649 surgically treated BM were included. According to postoperative MRI, complete resection was achieved in 407 (66%) of 649 BM and incomplete resection in 176 (29%) of 649 BM. Misjudgment of the EOR by the neurosurgeon was found in 25% of cases and resulted in an unexpected residual tumor which was evident on postoperative MRI in 122 (22%) BM. Preoperative tumor volume was significantly larger in incompletely resected BM. Moreover, local progression was significantly more common in cases with incompletely resected BM and was also associated with shorter overall survival. Conclusion: Our data of this study including multiple centers indicate that postoperative MRI is capable to detect a relatively high rate of unexpected residual tumors following resection of BM. Since local progression was more common in BM with residual tumors and this was associated with shorter survival, special attention should be paid to achieve a complete tumor resection.