ESTRO 2025 - Abstract Book

S1779

Clinical – Upper GI

ESTRO 2025

(surgery/RFA). 50% of lesions were type-1 reirradiation and all were repeat/induced oligometastatic disease (66.7% oligorecurrences). In four cases, multiple liver metastases were re-irradiated simultaneously.

Median initial dose was 50Gy (40-60Gy) while for reirradiation, 45Gy (30-50Gy) in 3-5 fractions (BED 10 = 100, range 48 132Gy). 100Gy BED 10 was unachievable in four cases due to visceral OARs constraints. Median reirradiation target coverage (PTV V (100%)) was 95% (SD ±7.6), while all mandatory OAR-constraints were met ( Table 1).

With a median-follow-up from reirradiation of 10 months (range 3-33months), the acute G1 toxicity was 50% with fatigue being the commonest (41.7%). No patient experienced acute ≥G2 toxicity. One patient developed late G4 colo hepatic fistula, following liver resection and RFA. No liver decompensation was reported.

Median interval between SABR-courses was 16.5 months (6-37months). Median, 1-year, and 2-year-OS from primary SABR course were 34 months (12-37m), 91.7% (95%CI54-99%) and 82.5% (95%CI 46-95%), respectively (Figure 1.A).

At analysis from SMART-reirradiation, 58% were alive, radiological responses were observed in 88.9%, and one patient relapsed in-field. Intrahepatic out-of-field recurrence was main pattern of failure (75%), while 58% had distant relapse (lung most common site, 41.7%). Median chemotherapy-free-interval was 5 months (range 3-11) and median-PFS 2 months (range 1-5). 1-year and 18-month-OS were 71.3% (95%CI 34-90%) and 57% (95%CI 20-82%), respectively (Figure 1.B) .