In the phase II CURB trial reported in The Lancet, Chiaojung Jillian Tsai, MD, PhD, and colleagues found that the addition of stereotactic body radiotherapy (SBRT) to standard-of-care systemic therapy was associated with improved progression-free survival in the total study population of patients with oligoprogressive non–small cell lung cancer (NSCLC) or breast cancer. Improvement was significant among patients with NSCLC but not among those with breast cancer.

Chiaojung Jillian Tsai, MD, PhD

Study Details

In the open-label trial, 106 patients from Memorial Sloan Kettering Cancer Center and six affiliated regional care centers in New York and New Jersey were randomly assigned between January 2019 and July 2021 to receive physician’s choice of standard-of-care systemic therapy with (n = 55; 24 with breast cancer and 31 with NSCLC) or without (n = 51; 23 with breast cancer and 28 with NSCLC) SBRT. Patients had received at least first-line systemic therapy, with oligoprogression defined as up to five progressive lesions on positron-emission tomography–computed tomography (PET-CT) or CT. The primary endpoint was progression-free survival, measured up to 12 months.

Progression-Free Survival

Study accrual was closed before reaching the target sample size after the primary efficacy endpoint was met during a preplanned interim analysis. Median follow-up was 12.1 months in the SBRT group and 11.6 months in the control group.

Median progression-free survival was 7.2 months (95% confidence interval [CI] = 4.5–10.0 months) in the total SBRT group vs 3.2 months (95% CI = 2.0–4.5 months) in the total control group (hazard ratio [HR] = 0.53, 95% CI = 0.35–0.81, P = .0035).

Among patients with NSCLC, median progression-free survival was 10.0 months (95% CI = 7.2 months to not reached) in the SBRT group vs 2.2 months (95% CI = 2.0–4.5 months) in the control group (HR = 0.41, 95% CI = 0.22–0.75, P = .0039). Among patients with breast cancer, median progression-free survival was 4.4 months (95% CI = 2.5–8.7 months) in the SBRT group vs 4.2 months (95% CI = 1.8–5.5 months) in the control group (HR = 0.78, 95% CI = 0.43–1.43, P = .43).

Adverse Events

Grade ≥ 2 adverse events occurred in 62% of patients in the SBRT group vs 41% of the control group. Those more common in the SBRT group included decreased lymphocytes (41% vs 20%), anemia (29% vs 12%), and decreased neutrophils (22% vs 12%). Grade ≥ 2 adverse events related to SBRT occurred in nine patients (16%) in the SBRT group, including gastrointestinal reflux disease, pain exacerbation, radiation pneumonitis, brachial plexopathy, and low blood cell counts.

The investigators concluded: “The trial showed that progression-free survival was increased in the SBRT plus standard-of-care group compared with standard of care only. Oligoprogression in patients with metastatic NSCLC could be effectively treated with SBRT plus standard of care, leading to more than a four-times increase in progression-free survival compared with standard of care only. By contrast, no benefit was observed in patients with oligoprogressive breast cancer. Further studies to validate these findings and understand the differential benefits are warranted.”

Dr. Tsai, of the Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, is the corresponding author of The Lancet article.

Disclosure: The study was funded by the National Cancer Institute. For full disclosures of the study authors, visit thelancet.com.