gms | German Medical Science

Objective: Introduction of the 5-ALA technique is one major advance in neuro-oncological surgery. Protoporphyrin IX (PpIX)-fluorescence was observed in about half of cerebral metastases. For now, no study found a correlation between the dichotomized PpIX-fluorescence of cerebral metastases and neither the origin or the histology of cerebral metastases. Aim of the present pilot study was to quantify PpIX-induced fluorescence of cerebral metastases.

Methods: 5-ALA induced fluorescence intensity was quantified in 17 patients suffering from cerebral metastases originating from NSCLC and breast cancer adenocarcinoma. A systematic spectrometric evaluation of tumor specimen and the resulted PpIX-induced fluorescence was performed using a spectrometer connected by optic fibers to a handheld probe. The difference between the maximum PpIX-fluorescence at 635 nm and the baseline fluorescence was considered as the PpIX fluorescence intensity of the metastasis.

Results: Each 9 patients suffered breast and lung cancer. The mean age was 62 year (37–81 years). 12 patients were female, 6 male. 10 cerebral metastases were considered as ALA-fluorescent by the surgeon. A PpIX fluorescence over 1.1x106AU was observed as “ALA-positive” by the surgeon.

The mean PpIX fluorescence of analyzed cerebral metastases was 1.6x106AU (9x104–4.5x106 AU). Also after quantification, we observed no significant difference in the levels of 5-ALA fluorescence in cerebral metastases originating from breast and NSCLC cancer metastases showed a significant higher PpIX-fluorescence (2x106 AU) as metastases originating from lung cancer (9.7x105 AU; p=0.3, Mann-Whitney test).

Conclusion: Firstly, PpIX fluorescence over 1.1x106AU was observed as “ALA-positive” by the surgeon. Secondly, quantification of 5-ALA fluorescence revealed no significant difference between cerebral metastases originating from breast cancer and NSCLC. Further studies with a greater patient collective are required.