Prognostic value of isolated tumor cells and micrometastasis of lymph nodes in invasive urinary bladder cancer

Introduction The prognostic significance of nodal micrometastasis and isolated tumor cells (ITC) in urinary bladder cancer (UBC) is unknown. We aimed to evaluate the prevalence, clinical impact, and clinicopathological characteristics of nodal micrometastasis and ITC in UBC. Materials and methods A total of 124 patients with UBC undergoing surgery were investigated. Detection of micrometastasis and ITC was performed using pancytokeratin immunohistochemistry (IHC). Histopathologic and clinical findings were correlated with patients' outcome. Result IHC detected nodal micrometastasis and ITC (pNmi group) in 12.9% (13/101) of originally node-negative patients and in 26.1% (6/23) of originally node-positive patients (pN+ group). The remaining 88 were truly node-negative patients (pN0 group). After IHC, all 13 patients in the pNmi group were upstaged from pN0 to pN1-2 and one patient in the pN+ group was changed from pN1 to pN2. Nodal micrometastasis and ITC were significantly associated with mixed urothelial carcinoma (UC) (p = 0.002), UC with discohesive pattern (p = 0.006), glandular differentiation (p = 0.043), lymphovascular invasion (p = 0.009), and budding-like tumor cell clusters (p = 0.002). The pNmi group had significantly worse cancer-specific survival than the pN0 group in univariate (p = 0.004) and multivariate (p = 0.040) analysis. Conclusion IHC frequently identified nodal micrometastasis and ITC in originally node-negative UBC patients on routine pathological examination. Nodal micrometastasis and ITC wereindependently associated with cancer-related mortality in UBC. IHC might be selectively used to detect micrometastasis and ITC in UBC having specific pathological features.