gms | German Medical Science

Objective: Recent studies showed that infiltration of brain metastases may extend beyond the pseudocapsule. Supramarginal resection of cerebral metastases was therefore advocated to reduce the incidence of local in-brain-progression. The aim of this study was to perform a post-hoc analysis to answer the following question: Does it make a difference if patients had no residual tumor cells on histopathological examination of resection margins (in terms of R0-resection in other surgical disciplines) or whether some cell populations were still detectable beyond the resection bed after fluorescence-guided microsurgery?

Methods: We included patients undergoing resection of metastatic brain disease as part of the Metastasys study protocol. The protocol included histopathological examination of tumor margins once 5-ALA assisted microsurgical resection was deemed complete. 5-ALA was given at a dose of 20mg/kg 4 hours preoperatively. Histological workup was performed using Cytokeratin AE1/AE3 immunostaining for epithelial tumors and Melan-A and HMB-45 for melanomas. Patients were followed up for local in-brain-tumor recurrence and overall survival. In a post-hoc analysis we dichotomized patients into those with histopathological confirmation of no tumor vs. the presence of tumor cells in the peritumoral zone. We employed two-tailed chi2 and Kaplan-Meier log-rank-testing with a cutoff p-value <0.05.

Results: Seventy-seven patients were included in the analysis. Mean age was 63 ±10 and 42 were female (54%). Average follow-up was 10 ±7 months. In 28 patients (36%), no residual tumor was found upon histological examination of the peritumoral zone. In 49 patients (64%), at least one sample contained evidence of tumor infiltration. Local recurrence was seen in 5/49 (10%) cases with residual tumor tissue, and in 4/28 (14%) cases without residual tumor tissue (p=0.64). Mean survival in patients with no remnant tumor tissue in the peritumoral zone (16.6 months, 95%CI; 10.7-22.6) did not differ significantly from the other patients with residual tumor tissue (14.1 months, C95%; 10.2-18.1, log rank=0.43).

Conclusion: Histopathological evidence of scattered residual tumor after microsurgical and fluorescence-guided resection of cerebral metastases does not appear to have a major impact on survival or local recurrence.