Presented during ESTRO 2026 by Prof. Shankar Siva in the session “Highlights Joint Green Journal The Lancet Oncology Top Clinical Trials,” long-term FASTRACK and FASTRACK II data support SABR as a non-invasive treatment option for selected patients with primary renal cell carcinoma who are medically inoperable or at high risk for surgery.
Stereotactic ablative body radiotherapy, also known as SABR, is increasingly being explored as a treatment option for patients with localized kidney cancer who cannot undergo surgery. While surgery remains a standard approach for many patients with renal cell carcinoma, a substantial number of patients are not suitable candidates because of age, comorbidities, surgical risk, or tumor-related factors.
In this pooled analysis, investigators combined long-term data from two prospective clinical trials: FASTRACK, a phase 1 study conducted at Peter MacCallum Cancer Centre in Melbourne, and FASTRACK II, an international non-randomized phase 2 trial conducted across academic hospitals in Australia and the Netherlands.
The analysis included patients with primary renal cell carcinoma who were medically inoperable or considered high-risk for surgery. Eligible patients were aged 18 years or older, had an ECOG performance status of 2 or less, tumors measuring 10 cm or less, and N0–N1 disease.
Treatment consisted of a highly focused SABR approach. Smaller tumors received a single fraction of 26 Gy, while larger tumors received 42 Gy delivered in three fractions.
Among 103 treated patients, the median age was 76.9 years, reflecting a population often seen in real-world practice where surgery may not be feasible. After a median follow-up of 5.0 years, local control remained high: 100% at 1 year, 98% at 3 years, and 98% at 5 years. Only one patient experienced local progression, which occurred alongside distant progression at 28 months.
The safety profile was also encouraging. Grade 3 adverse events occurred in eight patients, including abdominal or flank pain, nausea or vomiting, colonic obstruction, fatigue, and colitis or diarrhoea. All grade 3 or worse adverse events occurred within two years of SABR. No grade 4 adverse events and no treatment-related deaths were reported.
These findings provide important long-term prospective evidence supporting SABR as a non-invasive treatment option for selected patients with primary kidney cancer who are unsuitable for surgery. The authors noted that the results also support further evaluation of SABR in randomized trials, including comparisons with surgery in selected operable patients.
Read full paper here.