Prognostic significance of lymph node invasion in patients with metastatic renal cell carcinoma: a population-based perspective.

BACKGROUND: Virtually all staging schemes aimed at predicting the prognosis of surgically treated patients diagnosed with metastatic renal cell carcinoma (MRCC) omit the use of lymph node stage. In the current study, the authors tested the prognostic significance of lymph node stage in patients with MRCC within a population-based cohort of patients treated with cytoreductive nephrectomy to assess whether the inclusion of lymph node stage could improve the accuracy of cancer-specific mortality predictions.

METHODS: Within the Surveillance, Epidemiology, and End Results database, the authors identified 1153 patients who were treated with cytoreductive nephrectomy for MRCC, with (negative lymph nodes [N0] vs positive lymph nodes [N1-2]) or without (unknown lymph node stage [Nx]) lymphadenectomy. Of 797 patients treated with lymphadenectomy, 42.9% were found to have lymph node metastases. Kaplan-Meier plots and univariate and multivariate Cox regression analyses tested the statistical significance and the independent predictor status of lymph node stage, Fuhrman grade, tumor size, year of surgery, race, sex, and age in patients who underwent lymphadenectomy at the time of cytoreductive nephrectomy.

RESULTS: At 3 years after cytoreductive nephrectomy, the cancer-specific mortality-free rates of N1-2 versus N0 versus Nx patients were 14.4% versus 34.7% versus 34.0%, respectively. Lymph node stage represented the most informative variable and achieved independent predictor status in all multivariate models (P<.001). Consideration of lymph node stage added 3.2% accuracy to other predictors of cancer-specific mortality.

CONCLUSIONS: The findings of the current study indicate that lymph node stage should be considered in prognostic models. The TNM staging of MRCC patients also should rely on the stage of locoregional lymph nodes, because the 3-year cancer-specific mortality rates of lymph node-negative and lymph node-positive MRCC patients differ by as much as 20%.