In "Predicting Response to Immunotherapy by Evaluating Tumors, Lymphoid Cell-Rich Organs, and Immune-Related Adverse Events Using FDG-PET/CT", Nobashi and colleagues retrospectively investigate whether the evaluation of tumors, lymphoid cell rich organs, and immune-related adverse events (IRAE) with 18F-FDG PET/CT can predict the efficacy and outcome of immunotherapy in 40 patients (malignant melanoma, n = 21; malignant lymphoma, n = 11; renal cell carcinoma, n = 8) who underwent 18F-FDG-PET/CT before and after therapy with immune checkpoint inhibitors. Baseline and first restaging SUVmax for tumors, spleen, bone marrow, thyroid and pituitary glands were correlated with best overall response in the first year after therapy. Interval change between the baseline and first restaging PET showed that patients with a clinical benefit had a significant decrease in tumor parameters (P < 0.001). All patients with an increase of SUVmax in the thyroid of more than 1.5 (n = 5) on the first restaging scan had a complete response (CR) in 1 year. Patients with CR within 1 year (n = 22) were significantly associated with a favorable long-term outcome (P = 0.002). Nine patients with IRAE findings had CR at final evaluation. Among IRAE, thyroiditis was seen significantly earlier than arthritis (P = 0.040). Authors concluded that decrease of tumor parameters at early time-point PET was associated with favorable outcomes. Early development of thyroiditis is associated with a favorable early response indicator to immunotherapy.