ESTRO meets Asia 2024 - Abstract Book

S48

Interdisciplinary – Biomarkers

ESTRO meets Asia 2024

Keywords: Glioma, IL8, M2 Macrophage

144

Proffered Paper

Combination of ctDNA and PET identify patients at risk for relapse with irradiated early-stage NSCLC

Masaki Nakamura 1 , Shun-ichiro Kageyama 1 , Hidenari Hirata 1 , Taku Tochinai 2 , Hidehiro Hojo 1 , Atsushi Motegi 1 , Akinori Kanai 3 , Yutaka Suzuki 3 , Katsuya Tsuchihara 4 , Tetsuo Akimoto 1 1 Radiation Oncology, National Cancer Center Hospital East, Kashiwa, Japan. 2 Radiological Technology, National Cancer Center Hospital East, Kashiwa, Japan. 3 Computational Biology and Medical Sciences, University of Tokyo, Kashiwa, Japan. 4 Translational Informatics, National Cancer Center, Kashiwa, Japan

Purpose/Objective:

We reported that pretreatment circulating tumor DNA (ctDNA) detection can predict out-of-field recurrence in early-stage non-squamous non-small cell lung cancer (NSCLC) patients treated with radiation therapy [1]. Other markers reported as predictors of recurrence are tumor volume [2], consolidation to maximum tumor diameter ratio (CTR) [3], PET-CT standard uptake value (SUV) max [4], and carcinoembryonic antigen (CEA) value [5]. Here a more useful risk stratification method by combining ctDNA with other predictive factors was explored.

Material/Methods:

Patients diagnosed with cT1-2N0M0 non-squamous NSCLC and treated with proton beam therapy at our institution from January 2014 and December 2019 were selected. Only cases for which the following pre-treatment information was obtained were included. Gross tumor volume (GTV), CTR, PET-CT SUV max, CEA value, and plasma ctDNA detection. PBT was performed using the passive scattering method. The cumulative incidence curves of recurrence were calculated and compared using Gray's test. Progression-free survival (PFS) was calculated using the Kaplan–Meier method to estimate survival curves and the log-rank test to compare the survival curves.

Results:

Thirty-eight patients were analyzed in this study. At the median follow-up of 58 months (range, 15-97 months) in the surviving patients. Detectable ctDNA and SUV max > 5 was associated with inferior PFS (hazard ratio [HR], 5.1; 95% CI, 1.8-14.7 and HR, 3.0; 95% CI, 1.2-7.8). No significant differences were observed according to GTV, CTR and CEA value. The infield recurrence rate was significantly higher for high SUV max group compared to low SUV max group (p=0.03), and the out-of-field recurrence rate was significantly higher for ctDNA detection group compared to ctDNA undetection group (p<0.01). We created two risk groups: low risk for patients with both undetectable ctDNA and low SUV max; high risk for patients who either have detectable ctDNA or high SUV max. Patients in the high-risk group had a significantly worse PFS compared to patients in the low-risk group (HR, 8.7; 95% CI, 2.5-30.2).

Conclusion:

These results suggest that the combination of pre-treatment ctDNA and PET-CT SUV max is a better risk stratification method for predicting recurrence of early-stage non-squamous NSCLC treated with radiotherapy.