Introduction: In renal cell carcinoma (RCC), patients with metastatic disease who have achieved no evidence of disease after treatment of primary lesion and metastatic sites (M1NED) remain a poorly characterized cohort. Clinical management strategies are diverse, as they may be candidates for adjuvant immunotherapy or may be candidates for a strategy of surveillance to minimize treatment-related toxicities and optimize quality of life. Given the poorly characterized nature of this disease state and the uncertain utility of rendering a patient NED with metastatic disease, we sought to better characterize the clinical outcomes of this patient population. Methods: In this retrospective single-institution study at a large academic institution, we identified a cohort of patients with metastatic RCC who achieved M1NED status. Inclusion in our cohort required that the patient be rendered free of disease within 30 days of surgery from the index operation. Patients could be rendered free of metastatic sites of disease via metastasectomy, thermal ablation, or radiation. Using the Kaplan-Meier method, overall survival (OS), cancer-specific survival (CSS), systemic-therapy-free survival (ST-FS), and progression-free survival (PFS) were calculated. Additionally, we modeled the risk of progression using a Cox Proportional Hazard model. Results: The study included 84 patients who achieved M1NED status from 1989 to 2020. In the cohort, the median age was 56.3 years, patients had good performance (KPS: 85.6), 62 (73.8%) had clear cell histology, 1 site of metastatic organ involvement [67, 79.8%] and 63 (75%) had clinical T-stage T3. The most common metastatic site after being rendered NED was bone 23 (27.4%) and lung 21(25%). Median follow-up for the cohort was 86.2 mo. (95% CI: 49.2 199.9). Median OS for the cohort was 56 mo. (95% CI: 40.6 79.3), CSS was 78.4 mo. (95%CI: 40.6-79.3), ST-FS 46.5 mo. (95% CI: 27.2 NR) and PFS 13.8 mo. (95% CI: 10.0-16.5). On a Cox Proportional-Hazard model, only sarcomatoid histology was associated with an increased risk of progression [HR: 3.28 (95% CI:3.94-2.62), p<0.01]. Conclusions: Patients with RCC who are rendered M1NED are associated with favorable outcomes and may achieve a long interval of systemic therapy-free survival. This patient population demonstrates significant competing risks and many patients did well on surveillance before initiating systemic therapy. This study offers a unique insight into a classically hard-to-define population and a detailed study of this population may be helpful in clinical decision-making. SOURCE OF Funding: MSK P30
