Drug-related pneumonitis during mammalian target of rapamycin inhibitor therapy in patients with neuroendocrine tumors: a radiographic pattern-based approach

Purpose: The purpose of this study was to investigate the incidence of drug-related pneumonitis during mammalian target of rapamycin (mTOR) inhibitor therapy in patients with neuroendocrine tumours (NET) and characterise radiographic patterns of pneumonitis. Methods: Sixty-six patients (39 males, 27 females, age: 22-79 years) with advanced NET treated with mTOR inhibitor, everolimus, were retrospectively studied. Chest computed tomography scans during therapy were reviewed for abnormalities suspicious for drug-related pneumonitis by an independent review of two radiologists. Extent, distributions, and specific findings were evaluated in cases positive for pneumonitis. Radiographic patterns of pneumonitis were classified using the American Thoracic Society/European Respiratory Society classification of interstitial pneumonia. Results: Drug-related pneumonitis was radiographically detected in 14 patients (21%). Time from the initiation of therapy to pneumonitis was within 6 months of therapy in 10 patients (71%), while it ranged from 1.0 to 27.7 months. Pneumonitis was more common in patients who had never smoked (p = 0.03). Lower lungs were more extensively involved than upper and middle lungs. Peripheral and lower distributions were most common (n = 8), followed by peripheral and multifocal distributions (n = 3). Ground glass and reticular opacities were present in all cases, with consolidation in eight cases. The radiographic pattern of pneumonitis was classified as cryptogenic organising pneumonia (COP) pattern in eight patients, non-specific interstitial pneumonia (NSIP) pattern in five, and hypersensitivity pneumonitis pattern in one patient. Conclusion: Drug-related pneumonitis was noted in 21% of the advanced NET patients treated with everolimus. Radiographic pattern of pneumonitis was most commonly COP pattern, followed by NSIP pattern. (C) 2015 Elsevier Ltd. All rights reserved.