Risk factors and clinical characteristics of pneumonitis among patients with ALK-rearranged non-small cell lung cancer who received alectinib and thoracic radiotherapy.

Abstract

e20591 Background: Alectinib and thoracic radiotherapy (TRT) are important modalities in the management of ALK-rearranged non-small cell lung cancer. We therefore aimed to assess the incidence and risk factors of pneumonitis when these two treatments were combined. Methods: Patients with ALK-rearranged non-small cell lung cancer, receiving alectinib and TRT from January 2018 to December 2020 were reviewed, and the clinical and dosimetry data were collected. Logistic regression analyses were performed to evaluate risk factors associated with treatment-related pneumonitis (TRP). The prediction ability of dosimetry parameters for pneumonitis were examined by receiver-operating characteristic (ROC) curve analyses. Results: Of the 25 enrolled patients, 16 (64%) developed pneumonitis, and 12 (48%) developed grade 2 or higher pneumonitis. Logistics regression analyses revealed chemotherapy (OR = 8.750, 95% CI 1.207 - 63.428, p = 0.032), higher ipsilateral V5 (OR = 1.060, 95%CI 1.002 - 1.122, p = 0.043) and total lung V5 (OR = 1.083, 95%CI 1.000 - 1.174, p = 0.05) to be risk factors for TRP. Total lung V10, total lung V5, and ipsilateral V5 were strong predictors of TRP among the dosimetry parameters (AUC = 0.800, 0.786 and 0.781, respectively). After developing pneumonitis, 52% of patients recovered or improved, but one patient died due to respiratory failure. Conclusions: The combined use of alectinib and TRT significantly increased the risk of pneumonitis. Clinicians should consider the elevated risks and related dosimetric factors when deciding on combination treatment for ALK-rearranged NSCLC patients.