Low Rate of Cancer Events After Partial Nephrectomy for Renal Cell Carcinoma: Clinicopathologic Analysis of 1994 Cases with Emphasis on Definition of "Recurrence".

Background: Systematic pathology reviews in patients who experienced a clinical "recurrence" after partial nephrectomy for renal cell carcinoma (RCC) are anecdotal; therefore, definitions of "recurrence" varies considerably. We aimed to better define local recurrence by re-evaluation of surgical specimens of patients who experienced "recurrences" after partial nephrectomy at our institution.

Materials And Methods: Retrospective analysis of our institutional partial nephrectomy data set was performed. Patients who were clinically diagnosed with a local recurrence during the oncological follow-up after primary intervention for RCC were considered (January 2007 to December 2017, institutional review board number 5065, 15-1593). Re-evaluation of specimens coming from either primary treatment or management of the diagnosed recurrent disease was performed by 2 dedicated urologic pathologists. According to the findings of the pathology review, patients were assigned to 3 groups of disease event: (1) local recurrence of RCC; (2) new occurrence of RCC; and (3) micrometastatic RCC. Patient demographic characteristics, tumor pathological characteristics, oncological outcomes, disease treatment, and follow-up were reported for each patient. Cancer-specific survival was compared using the Kaplan-Meier method.

Results: Of 1994 cases recorded in the institutional database, data on 30 patients who were clinically diagnosed with a local recurrence were extracted. After pathology review, 9 patients were found who truly developed a local recurrence (group 1). Positive surgical margin status was poorly related to the likelihood of a true local recurrence as defined herein. Twelve patients were assessed with a new occurrence of RCC (group 2). Nine were diagnosed with micrometastatic RCC (group 3). With comparable follow-up lengths among the groups (39 [interquartile range (IQR), 32-45] versus 51.5 [IQR, 35-90.5] versus 42 [IQR, 13-65], group 1 versus 2 versus 3, respectively; P = .4), patients classified in group 1 and 3 had comparable cancer-specific survival (P = .5). Conversely, patients in group 2 were less likely to die of disease compared with group 1 and 3 patients (P = .02).

Conclusion: Careful pathologic classification of RCC disease events after partial nephrectomy has important prognostic implications and allows more precise study of the clinical significance of margin status.