Reliability of frozen section examination of obturator lymph nodes and impact on lymph node dissection borders during radical cystectomy: results of a prospective multicentre study by the Turkish Society of Urooncology.

Objective: To evaluate the accuracy of frozen section examination (FSE) for detecting lymph node (LN) metastases and whether we can use this information to decide the extent of LN dissection during cystectomy.

Patients And Methods: From August 2005 to August 2009 FSE of obturator LNs was performed in 118 patients with bladder cancer, who were undergoing radical cystectomy with extended LN dissection. Removed tissues from 12 well defined LN regions were sent separately for pathologic evaluation. The FSE results of obturator regions were compared with the final histopathologic results of these node regions.

Results: The mean number of removed nodes per patient was 29.4 ± 9.3 (median 28, range 12 to 51). The sensitivity, specificity, positive and negative predictive values of FSE for the 118 right obturator LN regions were 94.7%, 100%, 100% and 99%, respectively. The same values for the 118 left obturator LN regions were 86.7%, 100%, 100% and 98.1%, respectively. At final pathologic examination 28 of 118 (23.7%) patients had LN metastasis at obturator regions. Skipped metastasis was found in 15/90 patients (16.7%). Clinical and pathological stage of the primary tumour were found to be significant parameters for skipped metastasis (P = 0.008 and P < 0.001, respectively).

Conclusions: Performing FSE of the obturator LNs seems to be a reliable procedure for their evaluation with acceptable negative and positive predictive values. The information obtained with FSE of obturator LNs can be used to determine intraoperatively the extent of LN dissection, especially in patients with significant comorbidity. Our study also showed that if the clinical stage of the primary tumour is < cT2, the possibility of skipped metastasis is zero.