Oligoprogressive Renal Cell Carcinoma Treated with Stereotactic Body Radiation Therapy Versus Switching to a New Systemic Therapy

Purpose The promising results of stereotactic body radiation therapy (SBRT) in achieving local control in various primary tumors and metastatic sites have prompted evaluation of its association with outcomes in patients with oligoprogressive metastatic renal cell carcinoma (mRCC) during systemic therapy (ST). This study aimed to describe and compare the clinical outcomes associated with SBRT versus switching ST in patients with oligoprogressive mRCC. Methods We conducted a single-center retrospective study of patients with mRCC and up to five oligoprogressive extracranial metastases during ST. Patients were categorized into two cohorts: those treated with SBRT without changing ST (group A) and those receiving a change in ST (group B). The primary endpoints were progression-free survival (PFS) and overall survival (OS). Results A total of 67 patients (group A: 31; group B: 36) treated between 2012 and 2022 were included. After a median follow-up of 46 mo (40 mo for patients alive at the last follow-up), the median PFS was 11 mo in group A and 10 mo in group B ( p = 0.5), with 3-yr PFS rates of 19% and 27%, respectively. Median OS was 74 mo in group A and 41 mo in group B ( p = 0.052), with 3-yr OS rates of 70% and 51%, respectively. These differences should be interpreted as observational findings rather than evidence of causality. Conclusion In this retrospective analysis of patients with oligoprogressive mRCC during ST, SBRT was observed to have similar PFS and OS compared with a strategy of switching to a new ST. These findings are exploratory and do not establish causal effects.