In a single-center phase II trial reported in The Lancet Oncology, Tang et al found that metastasis-directed radiotherapy without systemic therapy was associated with good outcomes in patients with oligometastatic clear cell renal cell carcinoma.
Study Details
In the trial, 121 patients (intention-to-treat population; 120 in the per-protocol population) with one to five metastases were enrolled between July 2018 and May 2023 at MD Anderson Cancer Center. Patients underwent metastasis-directed stereotactic body radiotherapy to all disease sites (≤ 5 fractions at ≥ 7 Gy per fraction) without systemic therapy; additional metastasis-directed therapy was given for limited disease progression. The co-primary outcome measures were progression-free survival in the per-protocol population and systemic therapy–free survival in the intention-to-treat population. A 24-month median systemic therapy–free survival was predefined as the threshold for success of the strategy.
Key Findings
Median follow-up was 36.3 months (interquartile range = 26.5–51.1 months).
Median progression-free survival was 17.7 months (95% confidence interval [CI] = 14.9–22.4 months). Median systemic therapy–free survival was 34.0 months (95% CI = 28.3–54.1 months).
Grade ≥ 2 toxicities considered at least possibly attributable to metastasis-directed therapy occurred in 25 patients (21%), with grade 3 (n = 7) or grade 4 events (n = 1) reported in 8 patients (7%). Grade 3 toxicity events included back pain, leukocytosis, and pain not otherwise specified (two patients each). The grade 4 event was hyperglycemia. No treatment-related deaths were reported.
The investigators concluded: “Select patients with oligometastatic disease can be managed with serial metastasis-directed therapy with prolonged time off systemic therapy, favorable progression-free survival, and limited adverse events.”
Chad Tang, MD, of the Department of Genitourinary Radiation Oncology, Department of Translational Molecular Pathology, and Department of Investigational Cancer Therapeutics, The University of Texas MD Anderson Cancer Center, is the corresponding author of The Lancet Oncology article.
Disclosure: The study was funded by the Cancer Prevention and Research Institute of Texas, National Cancer Institute, and Myriad Genetics. For full disclosures of all study authors, visit thelancet.com.
