My dad is 53 years old and in good shape. he was diagnosed with stage 4 secondary liver cancer; the primary is still unknown. he has had a ct scan, an endoscopy, and a colonoscopy done. will a pet scan show something more?

Possibly: More important is the pathology. We rely on pathology and the immunochemistry. The pet may be helpful but sometimes we do not find a primary. This is called a cancer of unknown primary.

Maybe: Pet/ct scan is a very sensitive test and may very well find additional sites of disease. However, its sensitivity varies depending on the cancer histology and size of tumors. Unfortunately stage 4 means that the disease is advance and metastatic. Finding additional sites of disease may not significantly change the treatment plan and therefore may not be of additional help.

PET could help: A pet scan could be helpful as any malignancy greater than 1 cm in size should be hot. Small tumors can be behind folds or stool or be missed on colonoscopy for other reasons. A small intestinal cancer would not be found on upper or lower endoscopy. If the doctors are certain that the tumor is not a primary liver tumor, a pet scan should definitely be done.

A PET scan: May define the source, but does not change the outlook. No tumor that has infiltrated all lobes of the liver from another source has a good outlook. If it will not change therapy or outlook, i would not want a pet for me or a member of my family.