Von der PET-Bildgebung zur Theranostik – nuklearmedizinische Perspektiven beim kleinzelligen Lungenkarzinom

Positron-emission tomography/computed tomography (PET/CT) hybrid imaging is one of the mainstays in staging and restaging of small cell lung cancer (SCLC), for which ¹⁸F‑fluorodeoxyglucose (FDG) is widely used. Other tracers, some of which have theranostic potential, are increasingly being tested in clinical trials. The aim of this paper is to provide an overview of the capabilities of the FDG clinical standard in SCLC and to identify innovative PET tracers with theranostic potential that may become relevant in the setting of multimodal treatment of SCLC in the future. A PubMed search was carried out for this purpose, the results of which showed that FDG PET/CT has a high diagnostic accuracy for SCLC staging outside the brain. In terms of prognosis, this tracer is suitable for predicting overall survival (OS) at initial staging when determining the metabolic tumor volume (MTV) across all tumor lesions. In limited-disease SCLC, the maximum standard uptake value (SUVmax) of the primary tumor is also a prognostic measure for OS. A response to treatment can be reliably assessed by using FDG very early after the first cycle of first-line therapy. Innovative compounds that can be used theranostically include fibroblast activation protein inhibitor (FAPI) and tracers that address the delta-like ligand 3 (DLL3) or the chemokine receptor CXCR4, but these are not yet used therapeutically in SCLC. Currently, theranostically useable somatostatin receptor (SSTR) agonists (DOTATOC and DOTATATE) and SSTR antagonists (SSO120/110) are in clinical use as alternatives to FDG. Both SSTR tracer types demonstrate diagnostic and—at least for the antagonist—prognostic performances comparable to FDG. In addition, therapeutic SSTR agonists are already under clinical investigation in multimodal treatment of SCLC.