• Tests for serum tumor markers that may be elevated with specific cancers, such as CEA (colon), CA-125
  (ovary), CA 15-3 (breast), CA 19-9 (pancreas), prostate-specific antigen (prostate), alpha-fetoprotein
  (hepatoma, germ cell tumors), ßHCG (choriocarcinoma, germ cell tumors) and thyroglobulin and calcitonin
  (thyroid gland).

Imaging 
• Chest x-ray may reveal the most common tumor origin, carcinoma of the lung. It is often impossible, however,
  to distinguish between a primary lung cancer and a metastatic lesion within the chest. Sometimes chest CT is
  also helpful.
• Mammograms for all women diagnosed with CUPS. Fifty percent of females with isolated metastases in the
  lymph nodes in the armpit will have a breast cancer primary. This will not always be seen on a mammogram,
  however (a false negative result).
• It is not helpful to do extensive x-rays— bowel x-rays, for example—to look for a primary site unless there is a
  specific complaint in that area, such as constipation or gastrointestinal bleeding.
    The following imaging study is frequently done:
• Abdominal CT scan , especially if there are metastases in the liver. The scan may reveal the presence of the
  second most common malignancy causing CUPS, pancreatic cancer.