Article
5-ALA guided resection: A tool for brain metastasis surgery?
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Published: | May 20, 2009 |
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Objective: Although surgical treatment of cerebral metastases aims at complete resection by circumferential extirpation from the surrounding brain parenchyma, difficulties in identifying the metastases by differences in aspect and consistency and a propensity of some carcinomas for expanding growth into the adjacent parenchyma, often result into a mere gross total resection. For a complete resection of malignant gliomas, the benefits of fluorescence guided resection with 5 aminolaevulinic acid (5-ALA) have been proven. The objective of our study was to characterise 5-ALA fluorescence in brain metastases with a special emphasis on the detection of potential infiltration zones.
Methods: As yet, 13 patients with single brain metastases underwent 5-ALA fluorescence guided resection. A complete resection of the metastasis using the standard white light resection technique and an intraoperative documentation of the fluorescence signal was performed. Further, the resection cavity was evaluated for residual fluorescence positive (ALA+) tissue. Biopsies were taken from these ALA + areas and evaluated for morphology, differentiation and invasiveness.
Results: Neuropathology revealed non-small cell bronchial (n=9), oesophageal, ovarial, mamma and rectum carcinomas (n=1 each). 2 metastases were sharply demarcated from the brain, 8 expanded conically into the brain, and 3 had an infiltrative growth pattern. All tumours were little differentiated. 12 metastases showed 5-ALA-induced fluorescence, whereas 1 metastasis was ALA-negative (one bronchial carcinoma metastasis). Residual fluorescence tissue was present in all cases of ALA + metastases. In biopsies taken from ALA + areas (n=14) tumor was present in 50% of the samples.
Conclusions: Our study emphasizes that a sole circumferential resection of metastases might not be sufficient for a complete surgical resection. Our preliminary results demonstrate that the majority of brain metastases are ALA+ and that residual tumor tissue can be identified by ALA fluorescence. However, only half of the samples from these ALA + areas demonstrated active tumor. Therefore, additional studies on a greater collective of patients are needed to define the impact of this approach.