Top Line: What is the benefit of SABR for oligoprogressive cancer?
The Study: In the CURB trial, SABR improved PFS in patients with oligoprogressive NSCLC but not breast cancer. STOP was another randomized, phase 2 trial of SABR for patients with 1-5 sites of progression on standard systemic therapy. The trial included 90 patients with 127 metastatic lesions. SABR dose fractionation was site-dependent (most common 35 Gy/5 in 39%), and conventional palliative radiation was allowed in the non-SABR arm. Most patients had lung (44%), GU (23%), or breast (13%) cancer. The majority had only one oligoprogressive site (70%), and the most common sites were lung (43%), bone (20%), nodes (13%), and liver (13%). Median PFS was 8.4 months with SABR and 4.3 months without. Perhaps owing to the small population size, this difference did not reach statistical significance. Likewise, PFS at 2 years was numerically but not significantly different with SABR (24% v 9%). Local control at progressive sites was expectedly higher with SABR (70% v 38%). A major limitation of this trial was that a large proportion of patients in the standard arm (71%) still received radiation to oligoprogressive sites including 19% who received SABR in violation of the protocol. This may have diluted the true benefit of SABR observed in the trial.
TBL: In the STOP trial, SABR for oligoprogressive cancer did not result in a statistically significant improvement in PFS. | Schellenberg, Int J Radiat Oncol Biol Phys 2024
The Study: In the CURB trial, SABR improved PFS in patients with oligoprogressive NSCLC but not breast cancer. STOP was another randomized, phase 2 trial of SABR for patients with 1-5 sites of progression on standard systemic therapy. The trial included 90 patients with 127 metastatic lesions. SABR dose fractionation was site-dependent (most common 35 Gy/5 in 39%), and conventional palliative radiation was allowed in the non-SABR arm. Most patients had lung (44%), GU (23%), or breast (13%) cancer. The majority had only one oligoprogressive site (70%), and the most common sites were lung (43%), bone (20%), nodes (13%), and liver (13%). Median PFS was 8.4 months with SABR and 4.3 months without. Perhaps owing to the small population size, this difference did not reach statistical significance. Likewise, PFS at 2 years was numerically but not significantly different with SABR (24% v 9%). Local control at progressive sites was expectedly higher with SABR (70% v 38%). A major limitation of this trial was that a large proportion of patients in the standard arm (71%) still received radiation to oligoprogressive sites including 19% who received SABR in violation of the protocol. This may have diluted the true benefit of SABR observed in the trial.
TBL: In the STOP trial, SABR for oligoprogressive cancer did not result in a statistically significant improvement in PFS. | Schellenberg, Int J Radiat Oncol Biol Phys 2024