Association of Tumor Size with Risk of Lymph Node Metastasis in Clear Cell Renal Cell Carcinoma: A Population-Based Study

The purpose of this article was to explore the association of tumor size with lymph node metastases (LNM) risk in patients with clear cell renal cell carcinoma (ccRCC). Based on the Surveillance, Epidemiology, and End Result (SEER) database, patients diagnosed with ccRCC from 1988 to 2015 were included in this study. For each patient, personal characteristics, clinicopathological data, and survival outcomes were, respectively, collected. Subsequently, the odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to investigate the potential risk factors for LNM in ccRCC. Finally, Kaplan-Meier (KM) survival plots of overall survival (OS) and ccRCC-specific survival (CSS) were evaluated on the basis of different tumor sizes. A total of 8,292 patients were finally enrolled in the study, 1,170 of whom (14.11%) had LNM. According to the heatmap, we could intuitively interpret that larger tumor size was related to an increased risk of LNM obviously. The risk of LNM was evidently greater for larger tumor size (4-7 cm: OR = 2.415, 95% CI = 1.708-3.415; 7-10 cm: OR = 3.746, 95% CI = 2.677-5.242; and >10 cm: OR = 4.617, 95% CI = 3.302-6.457) compared with smaller tumor size (<= 4 cm). According to the KM survival plots of OS and CSS, we observed a gradual decline in survival with increasing tumor size, while the smallest tumor size had the best survival outcomes. These results indicated the positive relationship of tumor size with risk of LNM in ccRCC. And we also noticed continual decrease survival rates of OS and CSS with increasing tumor size.