Predicting pulmonary metastases among patients with indeterminate pulmonary nodules with renal cell carcinoma.

Abstract

505 Background: Indeterminate pulmonary nodules (IPN) are of uncertain significance in renal cell carcinoma (RCC) patients. We sought to determine the natural history of IPN in patients undergoing radical nephrectomy and to identify clinical variables associated with the development of lung metastases. Methods: We reviewed all radical nephrectomy patients at a single institution from 2005 – 2009 who had ≥1 IPN on chest computed tomography (CT) within 6 months prior to surgery and no evidence of distant metastates. All chest CTs were re-reviewed by a radiologist who was blinded to outcomes to independently determine number, size, location of nodules and whether the IPN appeared concerning for metastases based on nodule size, tissue density, and morphology. Univariate and multivariate Cox regression was used to assess associated predictive factors. Results: Of 258 patients with IPN, 73 (28%) developed pulmonary metastases. Median follow−up was similar in the groups at 36 months. Patients who developed pulmonary metastases had significantly poorer survival compared to those who did not (3-year DSS 54.5 versus 86.5 months, p<0.001), and 39 (53%) developed pulmonary metastases at the same location as the largest IPN. On univariate analysis, larger renal tumor diameter (HR 1.12, p<0.001), number of pulmonary nodules CT (HR 1.12, p 0.001), presence of hilar lymphadenopathy on chest CT were associated with both lung metastasis development and cancer-specific mortality. After adjusting for age, performance status, comorbidities, histology, and smoking status, higher tumor grade (HR 5.11, p 0.007), presence of tumor thrombus above the diaphragm (HR 4.38, p 0.013), perinephric (HR 4.29, p 0.002) or renal sinus (HR 2.16, p 0.045) fat invasion, and a chest CT concerning for metastasis by the radiologist (HR 2.91, p<0.001) were associated with development of pulmonary metastases. Conclusions: RCC patients with IPN who develop pulmonary metastases have a significantly poorer outcome. Independent predictors of developing lung metastases include tumor grade, presence of tumor thrombus above the diaphragm, perinephric or renal sinus fat invasion, and a chest CT concerning for metastasis.