Abstract Background: Patients with carcinoma of unknown primary (CUP) generally have a poor prognosis due to the lack of effective treatment options resulting from unclear diagnosis. Determining the tumor type through tumor origin testing, followed by cancer-specific genetic testing and precision therapy, may potentially improve the prognosis of CUP patients. Case presentation: Case 1: A 44-year-old male patient presented to a local hospital with lower limb pain.
