Overlap time is an independent risk factor of radiation pneumonitis for patients treated with simultaneous EGFR-TKI and thoracic radiotherapy.

Background: The exact rate and relevant risk factors of radiation pneumonitis (RP) for non-small-cell cancer (NSCLC) patients treated with the combination of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and thoracic radiotherapy have not been reported. Thus, this study aimed to investigate the rate and risk factors of RP for EGFR-positive NSCLC patients simultaneously treated with first-generation EGFR-TKI and TRT.

Patients And Methods: We retrospectively evaluated NSCLC patients simultaneously treated with first-generation EGFR-TKI and thoracic radiotherapy between January 2012 and December 2019 at Shandong Cancer Hospital and Institute, Shandong, China. RP was diagnosed via computed tomography and was classified according to the Common Terminology Criteria for Adverse Events v5.0. The risk factors of RP were identified using uni- and multivariate analyses.

Results: Of the 67 patients included, 44.78% (30/67) developed grade ≥ 2 RP. Grade ≥ 2 RP occurred within a median of 3.48 (range 1.07-13.6) months. The EGFR-TKI icotinib, ipsilateral lung V30 > 34%, and overlap time of > 20 days between EGFR-TKI and thoracic radiotherapy were identified to be independent predictive factors of grade ≥ 2 RP.

Conclusions: Grade ≥ 2 RP is highly frequent in NSCLC patients simultaneous treated with first-generation EGFR-TKI and thoracic radiotherapy. Icotinib, ipsilateral lung V30 ≤ 34%, and overlap time of ≤ 20 days for EGFR-TKI and thoracic radiotherapy will be helpful to lower the risk of RP in these patients. The addition of thoracic radiotherapy should be cautious, and the treatment strategies can be optimized to reduce the rate of RP for patients treat with simultaneous EGFR-TKI and thoracic radiotherapy.