Top Line: What happens if systemic therapy is deferred after SABR for oligometastatic disease?
The Study: The SABR-5 study has provided much useful information regarding the use of SABR for oligometastatic cancer. As a reminder, SABR-5 was essentially the single-arm, prospective continuation of the SABR-COMET trial where patients with up to 5 sites of oligometastatic disease were treated with SABR. This analysis of SABR-5 sought to compare outcomes for patients who received upfront systemic therapy at the time of developing oligometastatic disease (38%) to those who received delayed systemic therapy at progression (62%). Among the former group, 42% received induction systemic therapy prior to SABR. The upfront therapy group tended to have better performance status as well as a higher proportion of prostate (60%) and breast patients (24%). The delayed group had more colorectal, renal cell, head and neck cancer, and melanoma. After balancing the differences in baseline characteristics, patients who received upfront systemic therapy had significantly higher median PFS (34 v 23 months), but there was no difference in OS. When looked at another way, though, 41% of patients who didn’t receive upfront systemic therapy still hadn’t required systemic therapy at 3 years. Furthermore, SABR toxicity was lower with delayed systemic therapy (13% v 24% grade 2+ at 3 years).
TBL: In the SABR-5 study, patients who didn’t receive upfront systemic therapy along with SABR for oligometastatic disease had a higher rate of progression. However, they had less SABR toxicity and a sizeable proportion required no systemic therapy for years. | Baker, Int J Radiat Oncol Biol Phys 2024
The Study: The SABR-5 study has provided much useful information regarding the use of SABR for oligometastatic cancer. As a reminder, SABR-5 was essentially the single-arm, prospective continuation of the SABR-COMET trial where patients with up to 5 sites of oligometastatic disease were treated with SABR. This analysis of SABR-5 sought to compare outcomes for patients who received upfront systemic therapy at the time of developing oligometastatic disease (38%) to those who received delayed systemic therapy at progression (62%). Among the former group, 42% received induction systemic therapy prior to SABR. The upfront therapy group tended to have better performance status as well as a higher proportion of prostate (60%) and breast patients (24%). The delayed group had more colorectal, renal cell, head and neck cancer, and melanoma. After balancing the differences in baseline characteristics, patients who received upfront systemic therapy had significantly higher median PFS (34 v 23 months), but there was no difference in OS. When looked at another way, though, 41% of patients who didn’t receive upfront systemic therapy still hadn’t required systemic therapy at 3 years. Furthermore, SABR toxicity was lower with delayed systemic therapy (13% v 24% grade 2+ at 3 years).
TBL: In the SABR-5 study, patients who didn’t receive upfront systemic therapy along with SABR for oligometastatic disease had a higher rate of progression. However, they had less SABR toxicity and a sizeable proportion required no systemic therapy for years. | Baker, Int J Radiat Oncol Biol Phys 2024