Introduction: The extent of tumour resection is one of the most relevant prognostic factors in the treatment malignant gliomas (MG). Intraoperative 5-amminolevulinic acid fluorescence guided surgery (5-ALA-GS), facilitate tumour resection and allows a longer survival time. Residual tumour volume (RTV) and extension of resection (EOTR) can both be used as measures of tumour resection. Our aim was determine the relative prognostic value of RFT versus EOTR in the survival of MG patients, treated with 5-ALA-GS.
Methods: Retrospective study of all consecutive MG patients treated under 5-ALA-GS from December 2008 to December 2013. The aim of all surgeries was gross total resection of the MRI, TI/gadolinium identifiable tumour. Survival time was correlated either to RTV and EOTR ((initial tumour volume-residual tumour)*100/initial tumour volume), both calculated through an early MRI analysis with Osirix v3.7.1-32bits software. All patients were submitted to the same radiotherapy and temozolomide standard protocol. Statistical analysis was calculated with Prism6 v.6.0 for Mac OS-X.
Results: A total of 66 5-ALA-GS were preformed on 51 patients followed for 38,3±17 months. Average overall survival was 22±15 months (70,7 and 38,1% living patients at 12 and 24 months respectively). Early MRI was possible for 22 patients. Average RTV was 2,4±4,5cc and EOTR was 92,8±7,7%. No statistic differences were found on survival between EOTR <95% or >=95% (Mantel-Cox, p=0,97). Average survival for a RTV<0.5cc was 36 months and 66% two years survival was found, comparing with only 6 months and 30% two years survival for bigger tumoral residual volumes. Both populations were statistically similar regarding other prognostic variables studied
Conclusions: 5-ALA GS allowed an average EOTR higher 90%. With such high percentage or tumour resection however RTV had a higher prognostic significance. The authors advice its preferential use as the most relevant surgical prognostic factor. A residual tumour volume of less then 0,5cc added, on average, more 20 months of survival, when compared with higher residual volumes.
Patient Care: Hopefully it in allow identification of more relevant and accurate overall survival surgical related prognostic factors in the surgical treatment of malignant gliomas.
Learning Objectives: To access the relative prognostic value of the residual tumor volume versus of the extent of tumor resection (%) in the survival of malignant glioma patients, treated with 5-ALA fluorescence guided surgery.