Radiation recall pneumonitis induced by epidermal growth factor receptor-tyrosine kinase inhibitor in patients with advanced nonsmall-cell lung cancer

Background: Radiation recall pneumonitis (RRP) is a special form of radiation pneumonitis precipitated by certain pharmacological agents. Epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) is an effective treatment for advanced nonsmall-cell lung cancer (NSCLC) and has been reported as a potent radiation sensitizer. The incidence and general characteristics of EGFR-TKI-related RRP in patients with NSCLC remain unclear. Methods: Clinical records and serial chest images of consecutive patients with advanced NSCLC who had received thoracic radiotherapy (TRT) and EGFR-TKI treatment were retrospectively reviewed. EGFR-TKI-related RRP was diagnosed according to history, clinical manifestations, and radiographic characteristics. Potential risk factors were analyzed. Results: In total, 160 patients with NSCLC who received EGFR-TKI after TRT were identified. Of these patients, seven (4.4%) developed EGFR-TKI-related RRP. The median time interval between the end of radiotherapy and RRP was 124 days (range, 80-635 days) and that between the initiation of EGFR-TKI and RRP was 43 days (range, 18-65 days). No risk factor for the development of RRP was identified except that patients in whom EGFR-TKI was initiated within 90 days after the completion of radiotherapy had significantly higher rates of RRP than those of patients who began receiving EGFR-TKI treatment after 90 days (21% vs. 2.1%, p = 0.005). Conclusion: In patients with NSCLC who have a history of TRT, treatment with EGFR-TKI may induce not only interstitial lung disease but also RRP. Physicians should be aware of both unexpected adverse events when using EGFR-TKI.