Aim: To evaluate real-world local control outcomes and identify clinical and dosimetric determinants of local progression following metastasis-directed stereotactic ablative radiotherapy (SABR) within the international OligoCare cohort. Methods: OligoCare is a prospective observational registry (EORTC-ESTRO E2-RADIatE) evaluating SABR for oligometastatic prostate, breast, colorectal, and non-small cell lung cancer (NSCLC). The secondary endpoint, local progression, was defined as recurrence within the planning target volume (PTV), with death treated as a competing risk. Multivariate analyses were performed at both the patient and lesions levels (restricted to single-lesion patients) to account for confounding factors. Results: Between July 2019 and July 2025, 2,805 eligible patients were enrolled. Of these, 2,447 from 57 institutions received the recommended protocol treatment and were included in the analysis (median follow-up 31 months). The distribution of primary tumors was prostate (41.7%), NSCLC (21.7%), colorectal (21.2%), and breast (15.4%). The 1- and 3-year local progression rates were 5.0% and 11.4%, respectively. Among single-lesion patients (n = 1,714), a higher PTV minimum dose was the sole independent predictor of local control, with an 11% risk reduction per 10 Gy EQD2 increase (HR 0.89 [97.5% CI 0.82–0.98], p = 0.005). Although de novo OMD showed better local control compared to repeat OMD in the patient-level analysis (HR 0.65 [97.5% CI 0.47–0.91], p = 0.004), this effect was largely driven by higher dose delivery in de novo cases. Colorectal primaries faced a significantly higher risk of progression than prostate cancer (HR 2.63 [97.5% CI 1.71–4.05], p < 0.001), despite receiving the highest dose per fraction. Conclusion: SABR provides durable real-world local control in oligometastatic disease. Optimizing the minimum PTV dose appears the most critical technical factor for success. The inferior local control observed in colorectal metastases suggests a combination of treatment intensity challenges and intrinsic radioresistance, which could guide future trial design and dose-escalation strategies.
Local control in oligometastatic cancer patients following metastasis-directed stereotactic ablative radiotherapy: An interim analysis of ESTRO EORTC E2-RADIatE OligoCare cohort
Ricardi, Umberto;
2026-01-01
Abstract
Aim: To evaluate real-world local control outcomes and identify clinical and dosimetric determinants of local progression following metastasis-directed stereotactic ablative radiotherapy (SABR) within the international OligoCare cohort. Methods: OligoCare is a prospective observational registry (EORTC-ESTRO E2-RADIatE) evaluating SABR for oligometastatic prostate, breast, colorectal, and non-small cell lung cancer (NSCLC). The secondary endpoint, local progression, was defined as recurrence within the planning target volume (PTV), with death treated as a competing risk. Multivariate analyses were performed at both the patient and lesions levels (restricted to single-lesion patients) to account for confounding factors. Results: Between July 2019 and July 2025, 2,805 eligible patients were enrolled. Of these, 2,447 from 57 institutions received the recommended protocol treatment and were included in the analysis (median follow-up 31 months). The distribution of primary tumors was prostate (41.7%), NSCLC (21.7%), colorectal (21.2%), and breast (15.4%). The 1- and 3-year local progression rates were 5.0% and 11.4%, respectively. Among single-lesion patients (n = 1,714), a higher PTV minimum dose was the sole independent predictor of local control, with an 11% risk reduction per 10 Gy EQD2 increase (HR 0.89 [97.5% CI 0.82–0.98], p = 0.005). Although de novo OMD showed better local control compared to repeat OMD in the patient-level analysis (HR 0.65 [97.5% CI 0.47–0.91], p = 0.004), this effect was largely driven by higher dose delivery in de novo cases. Colorectal primaries faced a significantly higher risk of progression than prostate cancer (HR 2.63 [97.5% CI 1.71–4.05], p < 0.001), despite receiving the highest dose per fraction. Conclusion: SABR provides durable real-world local control in oligometastatic disease. Optimizing the minimum PTV dose appears the most critical technical factor for success. The inferior local control observed in colorectal metastases suggests a combination of treatment intensity challenges and intrinsic radioresistance, which could guide future trial design and dose-escalation strategies.
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