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Sources of Funding: none

Introduction

Introduction: The likelihood of metastatic disease with small renal masses (SRM) (≤3cm) is controversial. We sought to determine the risk of synchronous disease at the time of renal cell carcinoma (RCC) diagnosis.

Methods

Years 2004?2013 of the National Cancer Database (NCDB) were used to identify Renal Parenchymal Neoplasms. Patients were stratified by renal mass size in 1cm increments, starting at 1cm. Both clinical and pathologic nodal and metastatic disease were included. Additional variables including age, gender, race, tumor histology, grade, and treatment were analyzed. Logistic regression was performed to measure the association between tumor size and synchronous metastatic disease.

Results

Between 2004 and 2013, there were 328,467 cases with 45,510 (13.9%) presenting with synchronous metastases. 2.9% of patients with a SRM presented with metastatic disease (nodal or distant). Among patients with a tumor 1-2cm, 2-3cm, and 3.1-4.0cm the incidence of M1 disease at diagnosis was 2.8%, 2.7%, and 5.1%, respectively. In the cohort, 22,488 (6.8%) had pathologic metastatic disease, while 37,799 (11.5%) had clinical metastatic disease (Fig 1). Metastatic sites included lung (17.6%), bone (13.2%), liver (6.1%), and brain (3.6%). Patients with metastatic disease were more likely to be male (16.3% vs 13.6%, p<0.0001) and have a left renal mass (15.0% vs 13.4%, p<0.0001). On multivariate analysis, each 1cm size increment was associated with a corresponding increase in risk of metastatic disease. Compared to a 1.1?2.0cm mass, those with a mass >10cm were significantly more likely to have metastatic disease (OR: 19.8, p<0.0001). Increasing age (OR: 1.006), male gender (OR: 1.14), left side tumor (OR: 1.13) and poorly differentiated or anaplastic tumor grade (OR: 3.3 & 7.7 respectively) were also independently associated with increased odds of metastatic disease (all p<0.0001).

Conclusions

Renal mass size is associated with the presence of synchronous disease. In SRM, metastatic disease is present in approximately 3% of cases. This information may be used for risk stratification and patient counseling.

Funding

none