Main Session
Sep
29
PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care
3679 - FDG PET Imaging Biomarker Associations with Survival Outcomes After Radiotherapy for Oligoprogressive NSCLC
Presenter(s)
Jing Zeng, MD - University of Washington Radiation Oncology, Seattle, Washington
F. Yaseen1, D. S. Hippe2, J. Kang3, J. Zeng3, and S. R. Bowen3; 1Department of Biomedical Informatics and Medical Education, University of Washington, Seattle, WA, 2University of Washington, Department of Radiology, Seattle, WA, 3Department of Radiation Oncology, University of Washington/Fred Hutchinson Cancer Center, Seattle, WA
Purpose/Objective(s):
Localized radiotherapy (RT) is widely used to consolidate or prolong efficacy of systemic therapy, but improved biomarkers are needed to identify which patients derive durable benefit. We evaluated candidate pre/postRT FDG-PET biomarkers as prognostic factors for progression-free (PFS) and overall survival (OS) after RT for oligoprogressive non-small cell lung cancer (NSCLC)Materials/Methods:
24 metastatic NSCLC patients (13 females [54.2%], 35-85 years old [median: 70], 12 with driver mutations [50%]) treated with RT for oligoprogression while receiving systemic therapy were enrolled on a prospective institutional study from 2022-2025. Patients underwent FDG-PET/CT and blood collection prior to (preRT) and postRT (4-6 weeks). Imaging biomarkers included standardized uptake value (SUV) and total lesion glycolysis (TLG) metrics within three regions of interest: the irradiated metabolic tumor volume (MTV), lung volume, and liver volume. Paired pre/postRT changes were analyzed using Wilcoxon signed-rank tests. PFS and OS times were measured from preRT, with median prescribed dose was 50 Gy (range 28-63 Gy) in 4-25 fractions. Associations with PFS and OS were tested using Cox models. Interim analyses were exploratory and two-sided; p<0.05 was considered statistically significant without multiplicity correction. Results: Among 18 imaging-evaluable patients with preRT biomarkers, 13 (72%) experienced a radiographic PFS event (12 progressions [2 local, 10 distant] and 1 death without progression) and 7 (39%) died over a median of 27 months of follow-up. Median PFS and OS were 9 months and 26 months, respectively. Among 14 of 18 with pre- and postRT imaging, significant metabolic reductions were observed following RT across all SUV/TLG metrics (median decrease 61-71%, p < 0.0085 for each) but with little change in MTV volume on average (p = 0.73). PreRT MTV TLG (hazard ratio [HR] 1.7 per 1-standard deviation increase, p = 0.047) and volume (HR 1.8, p = 0.048) were significantly associated with worse PFS, while preRT, postRT, and change in peak, max, and mean SUV were not (p > 0.48). Both MTV TLG and volume remained significantly associated with PFS independent of driver mutational status (adjusted HR [aHR] 2.0, p = 0.024 and aHR 2.0, p = 0.029, respectively). No MTV biomarkers were correlated with OS (p > 0.066 for each). However, increased first quartile of lung SUV was associated with worse OS, both pre- (HR 3.0, p = 0.034) and postRT (HR 3.8, p = 0.041). This association was maintained after adjusting for driver mutations preRT (aHR 3.3, p = 0.041) but with similar effect size postRT (aHR 4.2, p = 0.064).Conclusion:
FDG PET metabolic disease burden across primary lesions and lung inflammation prior to RT were prognostic for long-term outcomes of patients with oligoprogressive NSCLC. Further prospective investigation and validation of these imaging biomarkers along with complementary circulating markers to guide personalized local and systemic treatment intensification is warranted.