Drug-related pneumonitis during mTOR inhibitor therapy in patients with neuroendocrine tumors: A radiographic pattern-based approach

Abstract

Purpose

Investigate the incidence of drug-related pneumonitis during mTOR inhibitor therapy in patients with neuroendocrine tumors (NET), and characterize 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 CT 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 ATS/ERS 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 distribution was most common (n=8), followed by peripheral and multifocal distribution (n=3). Ground glass and reticular opacities were present in all cases, with consolidation in 8 cases. The radiographic pattern of pneumonitis was classified as cryptogenic organizing pneumonia (COP) pattern in 8, non-specific interstitial pneumonia (NSIP) pattern in 5, and hypersensitivity pneumonitis (HP) 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.