Accuracy of the Extent of Bladder Cancer Nodal Metastases Found at Pelvic Lymphadenectomy at the Time of Cystectomy: Relation to Primary Tumor Stage

Objectives: To determine the minimum number of nodes (n(min)) that need to be removed to ascertain N-0 status with 90/95% certainty, and to determine the maximum number of nodes theoretically involved for a given number 'm' of involved nodes reported out of a total of 'n' nodes examined. Methods: 2,025 patients underwent cystectomy and pelvic lymphadenectomy, with pathologic stage <= pT(2) in 1,132 (55.9%) and >= pT(3) in 893 (44.1%). A mathematical model was utilized, using incidences derived from those having >= 10 nodes retrieved. Results: For stage <= pT(2) and 0, 1, or 2 positive nodes reported, n(min) are 2, 27, and 28, respectively, for 90% accuracy and 12, 29, and 29, respectively, for 95% accuracy. For stage >= pT(3) and 0, 1, or 2 positive nodes reported, n(min) are 19, 28, and 29, respectively, for 90% accuracy and 24, 29, and 30, respectively, for 95% accuracy. Conclusions: Accuracy of the extent of nodal involvement depends on the number of positive nodes reported, total number of nodes retrieved, and pathologic stage. This model allows clinicians to assess potential underestimation of the 'true' number of involved nodes for a given number of positive nodes out of a total number reported. Copyright (C) 2010 S. Karger AG, Basel