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Título

HOW ACCURATE IS CLINICAL STAGING FOR LYMPH NODE METASTASIS IN RENAL CELL CARCINOMA?

Introdução, Material, Método, Resultados, Discussão e Conclusões

Introduction: Patients with Renal Cell Carcinoma (RCC) undergo cross-sectional imaging of the abdomen for staging, most commonly a computed tomography (CT). Despite the prognostic relevance of lymph node (LN) metastasis, the accuracy of imaging studies to evaluate LN staging is limited.

Objective: To evaluate, in a systematic review, the accuracy of imaging studies for prediction of LN metastasis in patients with RCC.

Methods: We performed a review of the literature published in English language on PubMed and Google Scholar databases from 1990 to 2019. Keywords selected were (“renal cell carcinoma” or “renal cancer”) and (“lymph node”, “staging”, “lymph node metastasis”, “nodal metastasis”). After abstract evaluation, publications concerning the use of Imaging for LN staging were included.

Results: Based on a cutoff of nodes larger than 1 cm on the greatest diameter of CT imaging, series reported on sensitivity ranging from 69% to 78%, and Positive Predictive Values (PPV) from 16% to 62%. Based on the same criteria, reported Specificity varied between 70%- 86%, with Negative Predictive Values from 87% to 96%. According to a model developed by Gershman et al to predict LN metastasis, a 90% PPV would only be achieved by a lymph node axis > 3 cm. According to the same authors, evaluation of radiographic perinephric/sinus fat invasion may further increase accuracy in prediction of LN metastasis. Hutterer et al. reported on a nomogram including age, tumor size and symptoms with an accuracy limited to 78%. Concerning false negative cases, especially those with micrometastasis in LN < 1 cm, Babaian et al demonstrated that local symptoms and lactate dehydrogenase may help predict cases with LN involvement.

PET-FDG has demonstrated elevated specificity, although presenting sensitivity of 75%. Magnetic Resonance Imaging (MRI) appears to provide slightly higher sensitivity as compared to CT, although with limited specitificity (Ergen, 2004). Use of lymphotropic particle enhanced MRI has shown promising results (Guimaraes, 2008), although only in experimental context, as well as the use of sentinel node biopsy

Conclusion: CT presents limited accuracy for LN staging in RCC. A cutoff of 1 cm presents PPV of up to 62%, with NPV of up to 96%. A cutoff of 3 cm may raise PPV to 90%. Evaluation of fat invasion, tumor size and local symptoms may further increase accuracy of prediction. To date MR and PET imaging have not shown a consistent gain in LN staging accuracy.

Palavras Chave

kidney cancer; lymph node metastasis