Headline: Prospective data demonstrates near perfect local and distant control at 3 years out from definitive SBRT for renal cell carcinoma (RCC).
The Study: Like most malignancies, RCC occurs commonly in older populations that aren’t always ideal candidates for a radical nephrectomy. The first of its kind prospective multicenter phase 2 single-arm, TROG FASTRAK II trial enrolled 70 patients receiving definitive ablative radiation of a single localized biopsy-proven RCC tumor of any size. Of note, the median age was 77, and all were either not a candidate for or declined surgery. The prescription was 26 Gy x 1 for tumors ≤4 cm (n=23) and 42 Gy in 3 fractions for tumors >4 cm (n=47) with a median tumor size of 4.6 cm. Grade 3 toxicity occurred in 7 patients (10%) with no grade 4-5 events. Mean eGFR was 61.1 at baseline and 46.5 at 2 years after which it stabilized. At a median follow-up of 3.5 years, there were no local recurrences, which was the primary endpoint, and only one distant recurrence. Granted, RCC notoriously can have late distant recurrences, but 3.5 years is nonetheless a long disease-free (read: systemic therapy-free) interval for patients of this age.
TBL: “These outcomes support the design of a future randomized clinical trial of SBRT versus surgery for primary RCC.” | Siva, ASTRO 2023
The Study: Like most malignancies, RCC occurs commonly in older populations that aren’t always ideal candidates for a radical nephrectomy. The first of its kind prospective multicenter phase 2 single-arm, TROG FASTRAK II trial enrolled 70 patients receiving definitive ablative radiation of a single localized biopsy-proven RCC tumor of any size. Of note, the median age was 77, and all were either not a candidate for or declined surgery. The prescription was 26 Gy x 1 for tumors ≤4 cm (n=23) and 42 Gy in 3 fractions for tumors >4 cm (n=47) with a median tumor size of 4.6 cm. Grade 3 toxicity occurred in 7 patients (10%) with no grade 4-5 events. Mean eGFR was 61.1 at baseline and 46.5 at 2 years after which it stabilized. At a median follow-up of 3.5 years, there were no local recurrences, which was the primary endpoint, and only one distant recurrence. Granted, RCC notoriously can have late distant recurrences, but 3.5 years is nonetheless a long disease-free (read: systemic therapy-free) interval for patients of this age.
TBL: “These outcomes support the design of a future randomized clinical trial of SBRT versus surgery for primary RCC.” | Siva, ASTRO 2023