Late metastatic presentation is associated with improved survival and delayed wide-spread progression after ablative stereotactic body radiotherapy for oligometastasis

Background Stereotactic body radiotherapy (SBRT) is increasingly used to treat oligometastatic disease (OMD), but the effect of metastasis timing on patient outcomes remains uncertain. Methods An international database of patients with OMD treated with SBRT was assembled with rigorous quality assurance. Early versus late metastases were defined as those diagnosed <= 24 versus >24 months from the primary tumor. Overall survival (OS), progression-free survival (PFS), and incidences of wide-spread progression (WSP) were estimated using multivariable Cox proportional hazard models stratified by primary tumor types. Results The database consists of 1033 patients with median follow-up of 24.1 months (0.3-104.7). Late metastatic presentation (N = 427) was associated with improved OS compared to early metastasis (median survival 53.6 vs. 33.0 months, hazard ratio [HR] 0.59, 95% confidence interval [CI]: 0.47-0.72, p < 0.0001). Patients with non-small cell lung cancer (NSCLC, N = 255, HR 0.49, 95% CI: 0.33-0.74, p = 0.0005) and colorectal cancer (N = 235, HR 0.50, 95% CI: 0.30-0.84, p = 0.008) had better OS if presenting with late metastasis. Late metastasis correlated with longer PFS (median 17.1 vs. 9.0 months, HR 0.71, 95% CI: 0.61-0.83, p < 0.0001) and lower 2-year incidence of WSP (26.1% vs. 43.6%, HR 0.60, 95% CI: 0.49-0.74, p < 0.0001). Fewer WSP were observed in patients with NSCLC (HR 0.52, 95% CI: 0.33-0.83, p = 0.006) and kidney cancer (N = 63, HR 0.37, 95% CI: 0.14-0.97, p = 0.044) with late metastases. Across cancer types, greater SBRT target size was a significant predictor for worse OS. Conclusion Late metastatic presentation is associated with improved survival and delayed progression in patients with OMD treated with SBRT.