The impact of primary tumor resection on survival outcomes in de novo metastatic urothelial carcinoma patients: A multicenter retrospective study.

e16557 Background: De novo metastatic urothelial carcinoma (mUC) remains a challenging disease with a poor prognosis. While systemic therapy remains the cornerstone of treatment, the role of surgery to the primary tumor site remains unclear. This study evaluates the impact of local surgery on survival outcomes of patients (pts) with de novo mUC. Methods: A multicenter retrospective analysis was conducted on pts presenting with de novo mUC. The impact of the following factors on overall survival (OS) was examined in univariate analysis (UVA): age, gender, histology, primary tumor site, whether surgery to the primary tumor was performed, Eastern Cooperative Oncology Group (ECOG) performance status, serum albumin, presence of bone, liver, or lung metastases, and type and best response to first-line chemotherapy. Factors with p-value < 0.05 in the UVA were further assessed using multivariate cox-regression to identify independent predictors of OS. Results: We collected individual-level data of 755 pts with mUC treated with palliative chemotherapy across 59 centers. A total of 207 pts (27%) had de novo metastatic disease, which formed the basis of this analysis. Of the 207 pts, 32 (15.5%) underwent surgery to the primary tumor (cystectomy: 17, Nephrectomy: 15). Patients who underwent surgery demonstrated superior overall survival (OS) compared to those who did not, with a median OS of 41.8 months versus 20.8 months, respectively (p < 0.001). Additional factors associated with improved OS in UVA included ECOG PS 0-1, normal serum albumin, no progression during first-line chemotherapy, lower tract primary tumor site, and absence of bone or lung metastases. In multivariate analysis (MVA), surgery to the primary tumor remained an independent predictor of superior OS (HR: 0.50, 95% CI: 0.30-0.82, p = 0.006). Other factors that significantly affected survival in the MVA were albumin levels, tumor location and response to chemotherapy (table). Conclusions: Resection of the primary tumor was associated with improved OS in this retrospective cohort of pts with of de novo mUC. These results suggest that surgery may have a role in the management of selected pts and underscore the need for prospective studies to validate these findings. Predictors of OS in mUC (MVA). Variant HR (95% CI) P value Resection Of Primary 0.50 (0.30 – 0.82) 0.006 Low Albumin 1.645 (1.13 – 2.39) 0.009 Lung Metastasis 1.39 (0.97 – 1.99) 0.075 Response To Chemotherapy 0.45 (0.31 - 0.65) <0.001 ECOG (0-1) 0.71 (0.39 - 1.30) 0.270 Bone Metastasis 1.20 (0.77 - 1.87) 0.418 Lower Tract 0.65 (0.45 - 0.94) 0.021