Impact of tumor size on survival outcome in metastatic renal cell carcinoma patients (mRCC) treated with targeted therapy.

667Background: Recent research suggested that patients (pts) with small renal masses (4cm or less) were at low risk of disease recurrence after surgery. The impact of tumor size on survival in mRCC patients treated with targeted therapy (TKI) is unclear. Methods: Two cohorts were identified from the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC). Cohort 1 pts had initial nephrectomy for M0 RCC and subsequently developed metastasis during follow-up. Cohort 2 pts presented with de novo metastasis with or without cytoreductive nephrectomy. Cox regression was performed to assess the associations of primary tumor size (≤4 vs > 4cm) and overall survival (OS) on first line TKI, adjusted for histology, sarcomatoid features, tumor stage, number of metastasis, IMDC risk groups and age at TKI initiation. Results: 4089 pts with mRCC treated with first line TKI had primary tumor size data available. Patient characteristics were generally balanced between tumor size groups (≤4 vs > 4cm), excep...