2063 - Outcomes of Stereotactic Body Radiotherapy (SBRT) in Patients with Oligometastatic or Oligoprogressive Lung Metastases from Renal Cell Cancer (RCC)

X. Ji¹, and T. J. Dilling²; ¹Moffitt Cancer Center, Tampa, FL, ²Moffitt Cancer Center, Department of Radiation Oncology, Tampa, FL

Purpose/Objective(s): Kidney cancer is one of the 10 most common cancers in the United States. Renal cell carcinoma has some inherent radioresistance and standard-fractionation radiotherapy is of limited benefit. Stereotactic body radiotherapy (SBRT) is a treatment option for lung metastases, but few previous studies have specifically investigated SBRT to oligometastatic or oligoprogressive lung metastases from renal cell carcinoma. We conducted a retrospective analysis to demonstrate our rates of local control and overall survival for renal cell carcinoma patients with oligometastatic/progressive lung metastases treated with SBRT. Materials/

Methods: Single institution retrospective review of patients diagnosed with oligometastatic or oligoprogressive renal cell carcinoma with dominant metastasis to the lungs who were treated with SBRT between July 2009 and October 2023. Oligometastatic disease was defined as newly diagnosed, untreated renal cell carcinoma patients who developed up to 5 progressive extracranial metastases. Oligoprogressive disease was defined as renal cell carcinoma with 1 - 2 distant sites that continued to progress on active treatment while the primary site was controlled. Survival was calculated using Kaplan-Meier method. Median follow-up was estimated using the reverse Kaplan-Meier method. Association between local control and patient factors was analyzed using log-rank test.

Results: A total of 41 patients with oligometastatic or oligoprogressive renal cell carcinoma were treated with SBRT to 51 lung lesions. At the time of SBRT, the median age was 65.83 with the interquartile range (IQR) being (57.47 to 72.42) in our cohort study. The median tumor diameter was 1.50 cm (IQR 1.10 – 1.90). The median duration of follow-up was 36.00 months (IQR 11.18-66.54). Median radiation dose to the entire cohort was 6000cGy (range 5000 – 6000) with median number of fractions 5 (range 5 – 8). Overall, there were only 3 local failures at last follow-up. Twelve patients experienced progression elsewhere in the lung, and 19 patients experienced distant recurrence outside the lung. Median local control for the entire cohort was not reached; local control at 2 years was 97.3%. Median overall survival was 66.2 months (95% CI 43.3 – NA). Overall survival at 1, 2, and 5 years were 93.0%,75.2%, and 53.0%, respectively. Due to the small number of events, we were unable to identify patient factors associated with local failure on univariate or multivariate analysis.

Conclusion: SBRT is an effective treatment option for patients with oligometastatic or oligoprogressive lung metastases from renal cell carcinoma, offering excellent rates of local control. Most patients failed distantly, highlighting the importance of additional systemic therapies.