Development and Validation of a Nomogram for Predicting Brain Metastasis in Elderly Renal cell carcinoma Patients with Lymph Node Involvement

Background Renal cell carcinoma (RCC) is the most common malignant kidney tumor in the elderly. Although brain metastasis is relatively rare, it is associated with poor prognosis and diminished quality of life. This study aimed to develop and validate a predictive nomogram to estimate brain metastasis risk in elderly RCC patients with lymph node involvement. Methods Data were obtained from the SEER database for patients aged ≥ 65 years with RCC and lymph node metastasis (2013–2021). Univariate and multivariate logistic regression analyses identified independent risk factors for brain metastasis. A nomogram was constructed and validated using the area under the receiver operating characteristic curve (AUC), calibration curves, and decision curve analysis (DCA). Results A total of 2,475 patients were included and randomly assigned to a training cohort (n = 1,857) and validation cohort (n = 618). Liver metastasis, bone metastasis, radiotherapy, and surgery were independent predictors of brain metastasis. The nomogram demonstrated strong discrimination with AUCs of 0.858 (training) and 0.833 (validation), and excellent calibration in both cohorts. DCA confirmed superior clinical utility compared to conventional TN staging. Conclusion We developed and validated a reliable nomogram for predicting brain metastasis in elderly RCC patients with lymph node involvement. The model shows high discrimination and clinical applicability, and may help identify high-risk individuals who could benefit from early surveillance and individualized treatment strategies.