Diagnosis of micrometastasis in muscle invasive bladder cancer through immunohistochemistry analysis: is there indication for routine evaluation?

Background: Muscle invasive bladder cancer (BC) has a mortality rate of 50% in 5 years, despite the aggressive treatments currently used. The diagnosis of latent tumor cells in histologically normal lymph nodes (LN) may have prognostic value and may explain the tumoral recurrence in BC. Methods: Here we evaluated the use of the AE1AE3 cytokeratin marker through immunohistochemical examination of LNs to diagnose micrometastasis in patients with BC undergoing radical cystectomy (RC) and lymph node dissection. Sixty-one patients with pN0 diseases who were submitted to RC were studied. Conventional histological evaluation indicated that these patients did not have lymph node metastasis. Histological sections were reviewed and analyzed by immunohistochemistry (IHC) using the AE1AE3 antibody in single sections. Results: The total number of removed LNs was 832, averaging 13.64 LNs per patient. The IHC evaluation revealed that LN from 2/61 (3.27%) patients had micrometastasis. At the time of the last follow-up, 41% of all patients were in complete disease remission and 41.1% had died from BC. Conclusions: Our study shows that histological analysis using hematoxylin eosin (HE) method by experienced pathologists is sufficient for the diagnosis of LN metastasis and, therefore, there is no indication for routine IHC evaluation in patients at histopathological pN0 stage.