Case Study and Literature Review on Diagnosis and Treatment of Advanced Metastasis of Tumor with Unknown Primary Origin

Primary of Unknown Origin Cancer (CUP) is a metastatic tumor whose origin remains undetermined. The reason for this ambiguity in identifying the primary site remains unclear, possibly due to the tumor being too small or growing too slowly, or because the immune system has destroyed the tiny primary lesion. Most CUP patients receive only localized treatment or empirical systemic chemotherapy, leading to poor prognosis and shorter average overall survival. There is currently insufficient evidence-based medical support for the diagnosis and treatment of CUP. This study retrospectively analyzed clinical characteristics, diagnostic methods, treatment approaches, and prognostic outcomes of newly diagnosed CUP patients treated in our department. The findings aim to provide clinical guidance for diagnosis and treatment of CUP, with the goal of reducing diagnostic delays and improving patient outcomes.