Benjamin Serrano

1 Introduction Theranostics occupies a unique position in oncology because the same molecular target simultaneously enables disease visualization and therapeutic delivery. Unlike most anticancer strategies, where biomarkers primarily determine treatment eligibility, theranostic targets directly connect molecular imaging with targeted radionuclide therapy, making them the biological foundation of the theranostic paradigm.

1 Introduction For more than two decades, innovation in theranostics has been driven by one central scientific question: which molecular target should be imaged and treated next? This quest for actionable molecular targets transformed nuclear medicine, leading to landmark advances such as peptide receptor radionuclide therapy (PRRT) for neuroendocrine tumors and prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) for metastatic castration-resistant prostate cancer.