Cancer of unknown primary—state of the art

The Cancer of Unknown Primary (CUP) syndrome does not represent a single clinical entity but comprises a diverse group of malignant tumors. CUP is defined as a histologically confirmed metastatic malignant disease for which the primary tumor cannot be identified after completing initial diagnostics. Although its incidence has decreased, managing CUP patients remains a significant clinical challenge, particularly for those in the poor prognosis group, where the overall survival is merely 3 months. In this context, accurate diagnostics and prompt treatment initiation are crucial. While platinum-based chemotherapy still plays a central role in CUP therapy, the future holds promise with the advent of next-generation targeted therapies and immunotherapies guided by the results of advanced sequencing tools. These advancements offer hope for improving the bleak outcomes faced by these patients.