Is 5-ALA fluorescence of cerebral metastases a prognostic factor for local recurrence and overall survival?

Abstract

Background: 5-Aminolevulinic acid (5-ALA) fluorescence-guided resection technique was first introduced for malignant glioma. However, the impact of the 5-ALA fluorescence behaviour of cerebral metastases is still unclear. Aim of this study was to determine the impact of PpIX-fluorescence on the local progression-free and overall survival.

Materials and methods: A secondary analysis was performed and included an updated follow-up of 136 patients comprised in two previous studies. Additionally, 82 new patients were included. All patients underwent surgical resection of cerebral metastasis and intraoperative estimation of 5-ALA-induced fluorescence. The 5-ALA fluorescence behaviour of cerebral metastases was correlated with the rate of local recurrences, the local progression-free and overall survival.

Results: 218 patients suffering from cerebral metastatic spread fulfilled the inclusion criteria and were analysed: complete surgical resection could be achieved in 123/218 patients (56.4%). Dichotomised degree of surgical resection (complete vs. incomplete or questionable complete resection) was not related to dichotomized 5-ALA fluorescence of cerebral metastases (p = 0.66). 51 patients (23.4%) developed a local in-brain progression within or at the border of the resection cavity. Of these, 8 patients showed a PpIX-fluorescent metastasis. There was a trend towards a correlation between a higher local in-brain progression in PpIX-non-fluorescent metastases (p = 0.03). Median time to local in-brain progression was 4 ± 11 months. PpIX-fluorescent and PpIX-non-fluorescent metastases showed a significantly different progression-free survival (p = 0.01). PpIX-positive and -negative metastases showed a significantly different overall survival (20 and 14 months respectively; p = 0.006).

Conclusion: The 5-ALA fluorescence behaviour was related to the local progression-free and the overall survival in the present retrospective series and might be considered a prognostic marker. Further studies are required to appreciate the oncological impact of the 5-ALA induced fluorescence behaviour of cerebral metastases.

Keywords: 5-Aminolevulinic acid; Cerebral metastases; In-brain-progression; Overall survival; Recurrence.