The following imaging studies are occasionally done:
• CT, MRI and ultrasound studies of the area of known tumor and likely primary sites.
• Nuclear scans of bone, liver and thyroid. 

Endoscopy and Biopsy 
• Endoscopic evaluation of the colon, urinary tract and lung is performed when indicated by results of the
  previous studies. 
• Biopsy of suspicious lesions identified by x-rays may establish a primary site; breast, prostate, pancreas may
  need special studies on biopsy; hormone receptors, DNA, other studies.