Aims and Background: Consolidation immunotherapy with immune checkpoint Inhibitor (ICI) Durvalumab is an effective treatment for inoperable stage III non-small cell lung cancer (NSCLC) with a PD-L1 expression ?1% after definitive curative concurrent chemoradiotherapy (CCRT). This regimen carries an increased risk of immune-related and radiation-induced pneumonitis. Currently, there is no data on pneumonitis in patients receiving CCRT with an overall dose of 70 Gray (Gy) compared with the standard protocol of 60Gy +/- 10% in this setting.

Methods: This study analyzed retrospective data from 39 patients with unresectable NSCLC treated with CCRT. Patients received either 70Gy (n=29) or lower than 70Gy total dose (n=10) in 2Gy fractions. Cases of pneumonitis were further classified as RI-P (Radio-induced Pneumonitis) and ICI-P (ICI Pneumonitis) based on clinical and radiological findings.

Results: Of the 39 patients, 15 (38.5%) developed pneumonitis, with 10 out of 29 (34.5%) in the 70Gy group and five out 10 (50%) in the <70Gy group. There was no significant difference in pneumonitis and in occurrence of ICI-P vs. RI-P (26.7% vs. 73.3%) within both groups. The 70Gy group showed a significant benefit in mortality (p = <0.001).

Conclusions: 70Gy radiation dose for CCRT followed by durvalumab is a safe regimen and may provide clinical benefits in NSCLC patients compared to lower doses. Pneumonitis incidence aligns with previous literature. The higher dose is associated with improved overall survival, and reduced disease progression, potentially due to a longer consolidation time.