Diagnostic and Prognostic Applications of PET/CT in Small-cell Lung Cancer.

Background/Aim: In small-cell lung cancer, treatment differs between extensive disease (ED) and limited disease (LD). Chemotherapy plus immune checkpoint inhibitors is used in patients with ED. In patients with LD, chemoradiotherapy or chemoradiotherapy plus immune checkpoint inhibitors is used. Therefore, initial staging is important. Some reports exist on the utility of positron emission tomography-computed tomography (PET/CT); in particular, PET/CT can change the diagnosis between LD and ED. This review aimed to summarize the utility of PET/CT in small-cell lung cancer. Materials and Methods: We identified relevant articles published on PUBMED between 2010 and 2025 using selected keywords. We categorized the contents into disease staging, prognosis prediction, and topics, and then summarized section-by-section. Results: In addition to cancer staging between ED and LD, PET/CT can be used to evaluate semiquantitative indicators such as the maximum standard uptake value (SUVmax), total lesion glycolysis (TLG), and metabolic tumor volume (MTV). This is important as SUVmax, TLG, and MTV have been shown to predict treatment response. Conclusion: PET/CT is useful for staging small-cell lung cancers. However, reports on its usefulness for prognostic prediction are mixed, with some finding it useful and others not. Further research is needed as treatment approaches for small-cell lung cancer are evolving.