ESTRO 2024 - Abstract Book

S2157

Clinical - Upper GI

ESTRO 2024

Results:

Among 23 consecutive patients, 20 (87%) had synchronous distant metastatic disease with primary ESCC, and 3 (13%) had recurrent disease after esophagectomy or definitive chemoradiotherapy. Fifteen patients (65%) were male, and the median age of the patients was 66 (range: 42 – 89) years. Twenty-two patients (96%) received nivolumab monotherapy, and the remaining one (4%) received nivolumab plus ipilimumab. The dose fractionation of RT was as follows: 20 Gy in 5 fractions (n = 17), 30 Gy in 10 fractions (n = 5), and 40 Gy in 20 fractions (n = 1). RT was delivered to primary tumors and lymph node metastases in 5 patients (22%), primary tumors only in 8 patients (35%), lymph nodes only in 9 patients (39%), and pleural dissemination only in 1 patient (4%). With a median follow up of 16 months, the median LPFS was 6.9 months (95% CI: 4.2 – NA). Among 21 patients evaluable for PD-L1 status, there was no statistically significant difference in LPFS according to tumor proportion score (TPS) status (6-month LPFS: 66.7% for TPS ≥ 1% vs. 60.0% for TPS < 1%, hazard ratio = 1.1 [95% CI: 0.35– 3.7], P = 0.8). The best response in the irradiated lesions was 43% (10 of 23 patients), with a 17% complete response (CR, n = 4) and a 26% partial response (PR, n = 6). The median LPFS in 10 patients with CR and PR was 13.3 months (95% CI: 6.1 – NA). The disease control rate in the irradiated lesions was 100%. During the observation period, 4 patients (17%) experienced local disease progression within the RT field, resulting in esophageal stent replacement and total parenteral nutrition in one patient each. The median OS was 7.6 months (95% CI: 5.3 – NA). In terms of safety, RT-related grade 3 esophageal stenosis occurred in 1 patient (4%), and grade 3 immune-related adverse events occurred in 5 patients (22%), including one patient who experienced pneumonitis outside the irradiated field. There was no treatment related death.

Conclusion:

Regardless of PD-L1 status, palliative RT during immunotherapy showed durable local control in patients with metastatic ESCC without increasing treatment-related toxicities. Our retrospective study suggests that this could be a palliative treatment option in patients with metastatic ESCC who have tumor-related symptoms during immunotherapy, and further investigation is warranted.

Keywords: Palliative RT, Esophageal cancer, Nivolumab

735

Proffered Paper

Patterns of care and outcome of liver SBRT: results from a multicentre national quality project.

Pieter Deseyne 1 , Geert Silversmit 2 , Nicolas Jansen 3 , Yolande Lievens 4 , Luigi Moretti 5 , Sara Van Brussel 6 , Katleen Verboven 7 , Philippe Bulens 7 , Stephanie Deheneffe 8 , Jean-François Rosier 9 , Samuel Bral 10 , Sophie Cvilic 11 , Mark De Ridder 12 , Karin Haustermans 13 , Geneviève Van Ooteghem 14 , Karin Stellamans 15 , Nancy Van Damme 2 , Reinhilde Weytjens 16,17 , Ines Joye 16,17 1 University Medical Centre Groningen, Radiation Oncology, Groningen, Netherlands. 2 Belgian Cancer Registry, Belgian Cancer Registry, Brussels, Belgium. 3 Centre Hospitalier Universitaire de Liège, Radiation Oncology, Liège,