Survival outcomes of metastasis-directed therapy for solitary sites of metastatic clear cell renal cell carcinoma.

674 Background: Metastasis directed therapy (MDT) is associated with improved cancer-specific survival and delay in use of systemic therapy for metastatic clear cell RCC (mccRCC). Although the benefits of MDT may differ based on organ site of metastasis due to differences in disease biology, survival based on site of metastasis remain underexplored. We aim to evaluate survival outcomes of patients who underwent MDT for solitary sites of mccRCC. Methods: The Mayo Clinic Nephrectomy Registry was queried to identify adults undergoing radical or partial nephrectomy for unilateral, sporadic ccRCC from 2000 to 2019 with a single site of metastasis treated with MDT including complete metastasectomy or radiation, in lieu of systemic therapy. Overall and cancer-specific survival were estimated using the Kaplan-Meier method, with the duration of follow-up calculated from the date of metastasis to the date of death or last follow-up. Associations with time to death from RCC were evaluated using Cox proportional hazards regression models and summarized with hazard ratios and 95% confidence intervals (CIs). Results: In this cohort of 207 mccRCC patients, 152 underwent complete metastasectomy and 55 underwent radiation. 133 died at a median of 2.7 years (IQR 1.2-4.7) following metastasis, including 105 who died from RCC at a median of 2.2 years (IQR 1.0-3.9). The median duration of follow-up for the 74 patients who were still alive at last follow-up was 8.1 years (IQR 3.7-12.1). Overall survival rates (95% CI) at 2, 4, 6, 8, and 10 years following metastasis were 73% (69-79), 54% (48-62), 45% (38-52), 37% (30-44), and 32% (26-40), respectively; cancer-specific survival rates were 75% (69-81), 56% (50-64), 47% (41-55), 44% (37-52), and 42% (35-50), respectively. Age, poor performance status, presence of synchronous metastasis and asynchronous metastasis <1 year from nephrectomy, tumor size, and bone metastasis were associated with death from RCC (table). Conclusions: These findings provide useful survival benchmarks to patients who are considering MDT as a therapeutic option. In addition, synchronous and asynchronous metastasis <1 year from nephrectomy, poor performance status, and bone metastasis are significantly associated with worse survival from mccRCC. [Table: see text]