S823
Clinical - Lung
ESTRO 2026
Purpose/Objective: We aimed to analyze the predictive factors associated with recurrence in patients with non-small cell lung cancer (NSCLC) treated with stereotactic ablative
these results require confirmation in prospective studies. Keywords: SBRT, PD-L1, NSCLC
radiotherapy (SABR). Material/Methods:
Poster Discussion 3715
We collected 73 patients with early-stage NSCLC treated with SABR at a single institution between January 2021 and November 2023. Clinical and treatment characteristics were collected for all patients. Survival analyses were performed using Kaplan-Meier method and Long-rank test. Variables with a p-value <0.2 in the univariate analysis were included in the multivariate Cox proportional hazard model. Results: The mean age was 76 years (62 – 90 years), men were 61.6%, most patients were former smoker (70%) and 22.9% current smoker at the time of treatment, the mean pack-year index was 41.4 and 56.2% had chronic obstructive pulmonary disease (COPD). Adenocarcinoma was the predominant histology (81.8%), most often presented as peripheral lesions (63.9%). Immunohistochemistry to determine PD-L1 expression was performed in 75% of the patients with negative expression found in 56.1% of cases and low expression (defined as 1-49% tumor proportion score) in 26.3%. The patients were treated with a mean biological equivalent dose of 142Gy10 (range: 100 - 178median Gy10) and had a mean follow-up of 44 months.A total of 31% of patients experienced disease recurrence, of which 78.3% were considered distant metastases. The median progression free survival (mPFS) was 42.3 months. The variables included in the multivariable analysis were age, sex, COPD, PD-L1 expression and pack-year index. Only PD-L1 expression reached statistical significance. Low expression was associated with a higher risk of recurrence (HR: 4.62; 95% CI: 1.2-17.7; p= 0.026), while high expression showed a similar trend (HR: 3.76; 95% CI: 0.96-14.7; p= 0.058). The mPFS was 20 months in patients with positive PD-L1 expression (HR: 2.7; 95 CI: 1.08-6.76; p= 0.034), whereas it was not reached in those without expression.The median overall survival (mOS) was not reached; the 3-years and 5-years OS was 71% and 67% respectively, and PD-L1 expression showed the same trend as observed for PFS. The mOS was 20 months in patients with positive PD-L1 expression, whereas it was not reached in those without expression (HR: 2.7; 95% CI: 1.08 – 6.76; p=0.034). Conclusion: SABR provided local control and PD-L1 positive expression was associated with greater disease progression and reduced survival. These findings suggest that patients with PD-L1 expression may benefit from the addition of other therapies. However,
Survival of LD-SCLC patients followed with brain- MRI instead of the prophylactic cranial irradiation (PCI) - results of a prospective one-arm study Sergiusz Nawrocki 1 , Ewa Wasilewska-Te ś luk 1 , Anna Sugajska 1 , Andrzej Badzio 2 1 Oncology, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland. 2 Oncology, Medical University of Gdansk, Gda ń sk, Poland Purpose/Objective: The primary end-point was the overall survival. We assumed that follow-up with brain-MRI (every 3- months) and the use of SRT for brain metastases will not worsen survival in LD-SCLC patients without PCI. The other endpoints were intracranial tumor control at 12 and 24 months; the risk of brain metastases without PCI; the feasibility and efficacy of SRT. Material/Methods: It was a prospective, two-center one-arm study (NCT04168281). We included 87 patients who responded to radical chest chemoradiotherapy and had no brain involvement on brain MRI and any progression after completion of chemoradiotherapy. The group included 46 females and 41 males aged 52- 84 years, (median=67 years). PS of 80% patients was very good or good (WHO =0-1), in 20% medium (WHO=2). The first patient was enrolled 03.05.2019, the last patient 20.09.2024. The median and the average follow-up was 545 days and 650 days (range: 96-2097).The patients had brain MRI and chest and abdomen CT every 3 months until progression. The brain metastases were treated with SRT or WBRT or chemotherapy. Results: 30 (35%) of patients progressed in the brain. 61 (70%) had any progression.The median overall survival (OS) was 23 months, 2-y OS was 46% (95% CI= 32%-55%); the median OS of pts with brain metastases was 19 months and 2-y OS was 24% whereas for patients without brain metastases median OS was 27 months and 2-y OS was 56%. 14 (48%) patients with brain progression were treated with SRS 11 (38%) patients with WBRT, 3 (10%) patients with chemotherapy and one (3%) with surgery as the first treatment of brain metastases. The median PFS was 10 months for all patients and 8 months for brain metastases vs 15 months for progression outside the brain. Conclusion: The progression rate in the brain was lower than expected.The OS of the whole group was close to the
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