Introduction: Cerebral metastasis (CM) is the most common malignancy affecting the brain. Improved multimodal therapeutic options are required to strengthen the role of surgical treatment, which is already proven to be effective regarding survival and local recurrence. The emergence of surgical microscopes fitted with a fluoresceinspecific filter have facilitated fluorescein-guided microsurgery and identification of tumor tissue. Here, we present our experience with Fluorescein Sodium (FL) and the dedicated surgical microscope filterin 81 patients with CM.

Methods: 81 patients with CM of different primary cancers were included (39 women, 42 men, mean age 60 years). 5 mg/kg bodyweight, of FL was intravenously injected at induction of anesthesia. A YELLOW 560 nm filter (Pentero 900, ZEISS Meditec, Germany) was used for microsurgical tumor resection and resection control. Surgical reports were evaluated regarding the degree of fluorescent staining, postoperative MRIs within 48 hours regarding the extent of resection and postoperative courses regarding neurological outcome, complications and any adverse effects.

Results: Most patients (91 %, n=74) showed bright fluorescent staining, which markedly enhanced tumor visibility. 5 patients (8 %; 3 with adenocarcinoma of the lung, 1 with melanoma of the skin and 1 with renal-cell carcinoma) showed no or only insufficient FL staining. 9 patients (9 %) showed residual tumor tissue on postoperative MRI. In four other patients, radiographic examination could not exclude the possibility of very small areas of residual tumor tissue. Thus, gross-total resection was achieved in 88.8 % (n=72) of patients. No adverse effects were registered over the postoperative course.

Conclusions: FL and the YELLOW 560 nm filter are safe and feasible tools for safe increasing resection of CM. To further evaluate the effects of this technique the FLUCEM trial (FLUorescein Sodium in CErebral Metastases), an randomized, controlled, multi centre, open-label trial of fluorescein sodium-guided resection of cerebral metastases versus standard resection is planned.

Patient Care: The extent of resection of cerebral metastases facilitating this dye will increase and in turn possibly lead to a reduced local recurrency and better quality of life and prevent or alleviate neurologic deterioration. This of course is subject to verification in larger clinical trials.

Learning Objectives: To learn about fluorescence-guided tumor resection. Appreciate learning curve, advantages, drawbacks and pitfalls associated with sodium fluorescein and the dedicated microscope filter.

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