Confocal laser microscopy for assessment of surgical margins during radical prostatectomy.

OBJECTIVE: To evaluate the feasibility of confocal laser microscopy (CLM) for intraoperative margin assessment as faster alternative to NeuroSAFE during robot-assisted radical prostatectomy (RARP).

PATIENTS AND METHODS: Surgical margins were assessed during 50 RARP procedures in patients scheduled for NeuroSAFE. Posterolateral sections were cut and imaged with CLM and further processed conform the NeuroSAFE protocol. Secondary resection (SR) was performed in case a positive surgical margin (PSM) was observed with NeuroSAFE. Afterwards, the CLM images were non-blinded assessed for the presence of PSM. The accuracy of both NeuroSAFE and CLM was compared with conventional histopathology. Agreement for detection of PSM between NeuroSAFE and CLM was evaluated with Cohen's kappa coefficient. Procedure times were compared with a Wilcoxon signed ranks test.

RESULTS: In total 96 posterolateral sections of radical prostatectomy specimens were evaluated for the presence of PSM. CLM identified 15 (16%) PSM and NeuroSAFE identified 14 (15%) PSM. CLM had a calculated sensitivity, specificity, PPV and NPV of 86%, 96%, 80% and 98% respectively for the detection of PSM compared to definite pathology. After SR, residual tumor was found in six of thirteen cases (46%) which were all identified by both techniques. There was a substantial level of agreement between CLM and NeuroSAFE (κ = 0.80). The median procedure time for CLM was significantly shorter compared to NeuroSAFE (8 vs 50 minutes respectively, p<0.001). The main limitation of this study was the non-blinded assessment of the CLM images.

CONCLUSIONS: Compared to NeuroSAFE, CLM is a promising technique for intraoperative margin assessment and is able to reduce the time of intraoperative margin assessment.