In an individual patient meta-analysis reported in The Lancet Oncology, Shankar Siva, PhD, and colleagues found that patients receiving stereotactic ablative body radiotherapy (SABR) for primary localized renal cell carcinoma had long-term outcomes indicating that the treatment is safe and effective in this setting.
Study Details
The study involved data from the International Radiosurgery Consortium of the Kidney (IROCK) database on 190 patients with no prior local treatment who underwent SABR at 12 institutions in Australia, Canada, Germany, Japan, and the United States between March 2007 and September 2018. Patients with metastatic disease or upper-tract urothelial carcinoma were excluded.
SABR was given as a single fraction or in multiple fractions of > 5 Gy. The primary outcome measure was investigator-assessed local failure at 5 years.
These mature data lend further support for renal SABR as a treatment option for patients unwilling or unfit to undergo surgery.— Shankar Siva, PhD, and colleagues
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Key Findings
Median follow-up was 5.0 years (interquartile range [IQR] = 3.4–6.8 years). Overall, 81 patients (43%) received single-fraction SABR (median dose = 25 Gy) and 109 (57%) received multifraction SABR (median total dose = 42 Gy, median fraction dose = 8 Gy). Median tumor diameter was 4.0 cm (IQR = 2.8–4.9 cm). Among 128 patients with available operability details, 96 were considered inoperable by referring urologists. A total of 56 patients (29%) had a solitary kidney.
The 5-year estimate of freedom from local failure was 93.7% (95% confidence interval [CI] = 88.5%–96.6%). The cumulative incidence of local failure at 5 years with death as a competing risk was 5.5% (95% CI = 2.8%–9.5%); single-fraction SABR was associated with a lower risk of local failure (P = .020).
Cumulative incidence rates at 5 years with death as a competing risk were 10.8% (95% CI = 6.6%–16.2%) for distant failure and 13.0% (95% CI = 8.3%–18.6%) for any failure. The 5-year estimates were 92.0% (95% CI = 85.2%–95.8%) for cancer-specific survival and 63.6% (95% CI = 55.6%–70.6%) for progression-free survival.
Median baseline estimated glomerular filtration rate was 60.0 mL/min per 1.73 m², with a decrease of 14.2 mL/min per 1.73 m² observed after 5 years. Dialysis after SABR was required for seven patients (4%).
No grade 3 toxicity or treatment-related deaths were observed. One patient (1%) had an acute grade 4 duodenal ulcer and late grade 4 gastritis.
The investigators concluded, “SABR is effective and safe in the long term for patients with primary renal cell carcinoma. Single-fraction SABR might yield less local failure than multifraction [SABR], but further evidence from randomized trials is needed to elucidate optimal treatment schedules. These mature data lend further support for renal SABR as a treatment option for patients unwilling or unfit to undergo surgery.”
Dr. Siva, of the Department of Radiation Oncology, Peter MacCallum Cancer Centre, is the corresponding author for The Lancet Oncology article.
Disclosure: The authors reported that there was no funding for the study. For full disclosures of the study authors, visit thelancet.com.
