ESTRO 2024 - Abstract Book

S1642

Clinical - Lung

ESTRO 2024

Material/Methods:

We conducted a single-center retrospective analysis of 227 patients with unresectable stage III NSCLC who underwent definitive CCRT followed by consolidative durvalumab between 2018 and 2022. GTV was assessed at two time points: before starting CCRT for initial planning (GTV1) and at the fourth week of CCRT for adaptive planning (GTV2). Both relative and absolute GTV regressions from GTV1 to GTV2 were calculated. Receiver operating characteristic curves and Cox proportional hazards modeling were used to evaluate the impact of GTV parameters on progression-free survival (PFS) and overall survival (OS).

Results:

The median GTV1 volume was 90 mL (range, 5 – 840 mL) and the median GTV2 volume was 64 mL (range, 1 – 520 mL), resulting in median absolute and relative regressions of 18.6 mL and 25.0%, respectively. Among the GTV parameters, relative GTV regression demonstrated the strongest predictive value, with a C-index of 0.804 for in-field progression and 0.711 for overall progression. The 1-year PFS rates for the high (> 30%), intermediate (0 – 30%), and low (≤ 0%) relative GTV regression groups were 88.0%, 62.6%, and 14.3%, respectively (high vs. intermediate: HR 2.62, P=0.002; high vs. low: HR 8.65, P<0.001). Additionally, GTV2 volume showed stronger associations with both PFS and OS compared to GTV1 volume.

Conclusion:

Relative GTV regression during CCRT was identified as a promising early biomarker for unresectable stage III NSCLC. Further development of a multi-parametric predictive model is needed to improve predictive accuracy and potentially guide clinicians toward a patient-tailored therapeutic approach.

Keywords: Early predictor, non-small cell lung cancer

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Paloma Sosa-Fajardo 1 , Margarita Martín-Martín 2 , Javier Luna-Tirado 3 , Germán Valtueña-Peydró 4 , Ana María Álvarez González 5 , Paula Martin Barrientos 6 , Nuria Farré-Bernadó 7 , Elisabeth González-del-Portillo 8 , Maria Ángeles González Ruiz 9 , Nuria Azahara Linares 10 , Patricia Barrionuevo-Castillo 11 , Manuel Blanco-Villar 12 , Victoria Vera-Barragán 13 , María Mateos-Domínguez 14 , Jose-Enrique Castro-Gómez 15 , Marina Peña-Huertas 16 , José Zapatero-Ortuño 17 , Patricia Diezhandino 18 , Clara Eito-Valdovinos 19 , Leonardo Guerrero-Gómez 20 , Andrea Bobo-Jaureguizar 21 , Beatriz Vázquez Barreiro 22 , Mikel Rico-Oses 23 , Felipe Couñago 24 , On Behalf of the GOECP investigators 25