Accepted Answer

OK.

Well, generally an elevated temperature is the body's response to a substance released by blood cells in response to the body fighting an infection (as I'm sure you know).

But without other obvious signs of an infection -- it becomes more difficult to tell.

In patients with cancer, it can be other causes, such as reactions to medications, or the actual release of these fever-causing substances from the tumor itself.

Tumors can also cause the body to form blood clots, and having a blood clot in a vein is a potential cause for fever.

And finally, spread to the brain (where the body's central regulator of temperature is located) can be a cause for fevers.

So, there are many potential causes -- and unfortunately, without further investigation, it is impossible to tell over the Internet.
http://www.cancer.gov/cancertopics/pdq/supportivecare/fever/Patient/Page2

Expert:	Dr. Mark
Pos. Feedback:	99.8 %
Accepts:
Answered:	10/5/2009

Doctor (MD)

U.S. Physician/Surgeon in Neurosurgery