Survival and clinical prognostic factors in metastatic non-clear cell renal cell carcinoma treated with targeted therapy: A multi-institutional, retrospective study using the Korean metastatic renal cell carcinoma registry

Objectives The optimal treatment strategy for metastatic non-clear cell renal cell carcinoma (mNCCRCC) is still elusive and mainly extrapolated from evidence available for metastatic clear cell renal cell carcinoma. The aim of the study was therefore to investigate the survival outcomes and prognostic factors affecting survival in patients with mNCCRCC treated with targeted therapy. Materials and methods We analyzed a total of 156 patients (8.1%) with mNCCRCC among the total cohort of 1922 patients in the Korean metastatic RCC registry. We used Kaplan-Meier curve analysis to calculate the survival estimates for first-line progression-free survival (PFS), total PFS, and cancer-specific survival (CSS). We also used the log-rank test to compare the different groups and multivariate Cox-proportional hazard regression analyses to evaluate the prognostic factors for survival. Results The mNCCRCC group had significantly inferior survival outcomes in terms of first-line PFS, total PFS, and CSS (all P < 0.05). We found survival benefits in patients treated with first-line vascular endothelial growth factor-tyrosine kinase inhibitors (VEGF-TKIs, first-line PFS, and total PFS, all P < 0.05), cytoreductive nephrectomy (CSS, P < 0.0001), metastasectomy (CSS, P = 0.0017), and patients with metachronous metastasis (first-line PFS, total PFS, and CSS, all P < 0.05). Liver metastasis was the only significant prognostic factor for both first-line PFS and CSS (all P < 0.05). Conclusions In the current targeted therapy era, survival of mNCCRCC is still inferior in comparison with that of mCCRCC patients. We found survival benefits in patients treated with first-line VEGF-TKIs/CN/metastasectomy, and metachronous metastasis patients.