Value of 2-[¹⁸F]FDG-PET/CT in identifying immune-related adverse events in patients with melanoma or non-small cell lung cancer: a systematic scoping review

Purpose We aimed provide overview of the current literature regarding the diagnostic accuracy of 2-[F-18]FDG-PET/CT in detecting immune-related adverse events (irAEs) in patients with metastatic melanoma or non-small cell lung cancer (NSCLC), receiving treatment with immune checkpoint inhibitors (ICIs). Methods Following PRISMA guidelines for scoping reviews, we first performed a comprehensive literature search in Medline (PubMed), Embase, and Scopus. After applying inclusion/exclusion criteria and abstract/full-text review, 7 articles with 478 patients with melanoma and 2 with 155 patients with NSCLC were included. The reference standard was irAE, corroborated clinically, biochemically, histologically, or on other imaging modalities. Results Melanoma: Five studies reported the sensitivity of 2-[F-18]FDG-PET/CT, while two reported the prevalence of irAEs detected only by 2-[F-18]FDG-PET/CT (without other verification of irAEs). The clinically reported prevalence of irAEs ranged from 1 to 18% for thyroiditis, 4-19% for colitis, and 3-9% for pneumonitis. The sensitivity of 2-[F-18]FDG-PET/CT was 89-100% for thyroiditis, and 100% for colitis, pneumonitis, and sarcoid reaction in mediastinal lymph nodes. Only one study reported specificity and found a value of 49% for colitis, 96% for pneumonitis, and 81% for thyroiditis. NSCLC: The prevalence of 2-[18F]FDG-PET/CT detected irAEs 9-33% for thyroiditis, 34-40% for colitis, and 17-20% for pneumonitis. A sensitivity of 67% was found for thyroiditis. Results regarding specificity were lacking. Conclusion Studies suggested that 2-[F-18]FDG-PET/CT is a valuable, non-invasive tool for detecting adverse events to anticancer treatment with ICIs. Sensitivity for the most commonly investigated irAEs, including thyroiditis, colitis, and pneumonitis, was generally high. Specificity was more varying and poorly reported. Prospective studies exploring the clinical impact are needed to determine the role and optimal timing of 2-[F-18]FDG-PET/CT in identifying irAEs.