Presentation Authors: Ryan Steinberg*, Brett Johnson, Ivan Pedrosa, Jeffrey Cadeddu, Dallas, TX
Introduction: No reliable predictors exist to define the oncologic behavior of renal masses. Clear cell renal cell carcinoma (ccRCC) is known to have an aggressive histology with metastatic potential. Renal mass biopsy has potential risks. A clear cell likelihood score (ccLS) based on multiparametric magnetic resonance imaging (mpMRI) has shown reasonable accuracy in identifying ccRCC in a retrospective cohort. We now report the diagnostic performance of ccLS to predict ccRCC in a prospectively cohort of renal mass patients.
Methods: Patients with a known renal mass who underwent mpMRI at a single institution between June 2016 and April 2018 were prospectively assigned a ccLS in the clinical mpMRI report. Retrospective analysis included those with available pathological tissue diagnosis (biopsy or surgery). ccLS was reported based on the likelihood of ccRCC histology using a previously reported Likert interpretation algorithm. Lesions were grouped according to clinical stage (cT1a, cT1b, cT2-4) and confusion matrix analysis was performed. A ccLS score of 4 or 5 was considered positive for ccRCC pathology and 1 or 2 considered negative.
Results: One hundred nine patients (mean age 62.9 Â± 6.4 years) with 125 renal masses were identified. Mean tumor size was 5.0 Â± 3.4 cm. Figure 1 demonstrates the histology distribution based on ccLS. For all lesions, ccLS demonstrated an overall accuracy of 89.6%, sensitivity of 92.3%, specificity of 85.1%. The diagnostic ability of ccLS improved as the clinical stage increased (Table 1). Notably, a ccLS of 1 or 2 had a 100% specificity for all cT1 lesions, while a ccLS of 4 or 5 had a 100% specificity in cT2-4 tumors.
Conclusions: Using prospective data, mpMRI can reasonably identify ccRCC histology in renal masses of all sizes with improved performance in higher stage lesions. Renal mass biopsy can be omitted in larger or more advanced ccLS 4-5 lesions and help identify patients with large tumor who are candidates for active surveillance.