Development and validation of a predictive model for postoperative metastasis of upper tract urothelial carcinoma after radical nephroureterectomy and analysis of risk factors for different metastatic sites: a multicenter study

Purpose To develop a prediction model for assessing the risk of postoperative metastasis in upper tract urothelial carcinoma (UTUC) patients after radical nephroureterectomy (RNU) and to analyze independent risk factors for metastasis at different sites. Methods We retrospectively analyzed data from 555 UTUC patients who underwent RNU at 3 medical centers between January 2012 and August 2023. Patients were randomly divided into a training cohort (n = 388) and a validation cohort (n = 167) at a 7:3 ratio. Univariate and multivariate Cox regression analyses were performed in the training cohort to identify postoperative metastasis risk factors. A nomogram was developed based on these factors and validated. In addition, independent risk factors for metastasis at different sites were analyzed. Results Among the 555 patients, 122 (22.0%) developed postoperative metastasis. Middle and lower ureteral tumors, T stage >= T3, high-grade tumors, lymphovascular invasion (LVI), and a prognostic nutritional index (PNI) < 48.75 were associated with poorer metastasis-free survival (MFS). The nomogram achieved C-indexes of 0.816 and 0.812 in the training and validation cohorts. Age < 65 years was a risk factor for lymph node metastasis, tumor size and necrosis predicted liver metastasis, and a higher preoperative platelet-to-lymphocyte ratio (PLR) was associated with bone metastasis. Median overall survival (OS) for lymph node, lung, liver, multiple sites, bone, and brain metastasis were 14, 10, 6, 5.5, 5, and 4.5 months, respectively. Conclusion The prediction model developed effectively assesses postoperative metastasis risk in UTUC patients' aids in guiding individualized treatment. The risk factors for different metastasis sites are generally similar, with slight variations, which may offer new directions for future research on site-specific therapeutic strategies.