[Clinical Practice of Carcinoma of Unknown Primary]

Carcinoma of unknown primary(CUP)is defined as the presence of metastatic cancer documented in the absence of an identifiable primary tumor site. According to this definition, between 1% and 5% of cancer patients are diagnosed with this clinical entity. CUPs are a heterogeneous group of neoplasms with widely varying natural histories and biologic characteristics. In this broad category, there are 5 major diagnoses, as assessed by light microscopy: (1)poorly differentiated neoplasm,(2) well differentiated and moderately differentiated adenocarcinoma,(3)squamous cell carcinoma(4)neuroendocrine tumor, and(5)poorly differentiated carcinoma(with or without features of adenocarcinoma) .It has been reported that the prognosis of patients with CUP is poor. The median survival time(MST)is 6 to 9 months, and less than 25% of the CUP patients are alive 1 year after diagnosis. Previous trials with a variety of chemotherapeutic regimens have produced response rates of less than 50% with negligible benefit in terms of median survival. Platinum -containing regimens have induced higher response rates than those without it in patients with CUP, and platinum is considered a key drug in UPC treatment.