ESTRO 2024 - Abstract Book

S1629

Clinical - Lung

ESTRO 2024

1221 patients were identified, 48.1%, 29.6%, and 22.3% were treated with RT, cCRT and sCRT respectively. Baseline characteristics are described in Table 1. GTV mean was 127.4cc, and 15% of all patients had more than two comorbidities. After adjusting for clinical variables, patients with tumours above GTV mean had significantly worse overall survival (HR=1.37, [1.16, 1.6], P<.001). Median Survival (in years) for patients with GTV≤127.4cc treated with cCRT, RT, and sCRT were 2.63 (2.25 – 3.52), 2.1 (1.39 – 3.07), and 1.72 (1.32 – 2.49) respectively, compared to 2.58 (1.69 – 4.5), 1.29 (0.87 - 2.06), and 0.95 (0.69 – 1.51) for GTV>127.4cc. The formal test comparing the multivariable Cox regression model with an interaction to the model without an interaction term (interaction P=.047) shows the hazard for death increases more with increasing GTV as a continuous variable for patients being treated with RT (HR=1.18, [0.99, 1.41], P=.06) or sCRT (HR=1.28, [1.05, 1.55], P=.01) than it does for patients treated with cCRT (HR=1.01, [0.87, 1.17], P=.88). The marginal effect of the interaction between treatment and GTV is shown in Figure 1.

Conclusion:

The effect of GTV on patient survival differs based on the curative-intent treatment strategy. In this real-world cohort of patients with stage III NSCLC, the detrimental impact of tumour volume is lower in patients treated with cCRT compared to sCRT and RT alone. Our data suggests that patients with larger GTV derive a clinically meaningful benefit with curative-intent RT (with or without chemotherapy) and should not be denied treatment. This finding suggests that cCRT is a reasonable treatment strategy in patients with bigger tumours. However, patients treated