ESTRO 2025 - Abstract Book

S1871

Clinical – Upper GI

ESTRO 2025

References: Wydmański J, Suwinski R, Poltorak S, Maka B, Miszczyk L, Wolny E, Bielaczyc G, Zajusz A. The tolerance and efficacy of preoperative chemoradiotherapy followed by gastrectomy in operable gastric cancer, a phase II study. Radiother Oncol. 2007 Feb;82(2):132-6. doi: 10.1016/j.radonc.2007.01.009. Epub 2007 Feb 6. PMID: 17287038.

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Poster Discussion Depth of Response and Duration of Response are Predictive of Survival for Hepatocellular Carcinoma treated with SBRT and Immunotherapy Chi Leung Chiang 1 , Sik Kwan Chan 1 , Keith Wan Hang Chiu 2 , Francis Ann Shing Lee 3 , Wenqi Chen 4 , Natalie Sean Man Wong 3 , Ryan Lok Man Ho 5 , Venus Wan Yan Lee 3 , Kwan Man 6 , Albert Chi Yan Chan 6 1 Department of Clinical Oncology, The University of Hong Kong, Pokfulam, Hong Kong. 2 Department of Diagnostic Radiology, The University of Hong Kong, Pokfulam, Hong Kong. 3 Department of Clinical Oncology, Tuen Mun Hospital, Tuen Mun, Hong Kong. 4 Clinical Oncology Center,, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China. 5 Radiotherapy and Oncology Department, Gleneagles Hospital, Wong Chuk Hang, Hong Kong. 6 Department of Surgery, The University of Hong Kong, Pokfulam, Hong Kong Purpose/Objective: Our previous studies showed that 42-50% of patients with locally advanced hepatocellular carcinoma (HCC) achieved complete remission (CR) after combined stereotactic body radiotherapy and immunotherapy (SBRT-IO). We report exploratory analyses of associations between overall survival (OS) and depth of response (DpR), duration of response (DoR), and early tumor response (ETR). Material/Methods: Two prospective studies between January 2018 and December 2022 were included in this analysis. DpR was defined as maximum tumor shrinkage from baseline per modified RECIST. DoR was defined as time from the first complete / partial response until progression. ETR was defined as complete remission in the first follow-up images (around 3 months). Association between OS and DpR or DoR were evaluated by scatter plot. Cox proportional hazard models were used to evaluate the association between ETR and OS. To minimize immortal time bias, the DpR and ETR analyses included patients who survival ≥6 months. Results: A total of 63 patients were enrolled (58 male [92.1%]; median age, 69 years [range, 18-90 years]); 38 patients (60.3%) had macrovascular invasion, and the median tumor diameter was 10 cm (range, 3.8-31.1 cm). Total 63, 48, and 63 patients included in the DpR, DoR, and ETR analysis respectively. Tumor shrinkage occurred in 60 / 63 (95.2%) patients with the mean (SD) DpR was -52.9 % (34.5%). Those with deep response (DpR -100% to -60%) had longer OS than those with DpR > -60% (HR 0.51, 95% CI 0.26-0.88). The median DoR was 30.1 months (range, 0.2-71.8), those with DoR ≥ 15 months had improved OS compared to those with DoR < 15 months. Patients with ETR had improved OS (50.1 months vs. 28.4 months, p=0.003) and was independent predictor in multi-variable analysis (HR, 0.2, 95% CI, 0.08-0.65). Conclusion: Deeper, longer, and earlier responses were associated with better survival in locally advanced HCC patients treated with SBRT-IO.

Keywords: hepatocellular carcinoma, SBRT, immunotherapy