My Father has been cancer free for 3 years but in January he began showing symptoms that the cancer may may have returned.

He has had a PET scan, chest x-rays, blood work, CT scan, numerous scopes and all have come back negative for cancer.

During an EGD they took a biopsy of an ulcer that they found and it came back positive for cancer. Is it possible that the cancer was missed on all of the other tests? All tests have been done within the past 2 months.

Also...
He was originally diagnosed with thrush but the medicines did not cure it. It appears as if the thrush has just gotten worse. Is thrush best treated through an IV? Is thrush really this painful? Or could something else be wrong?

My Dad has lost 20lbs and can not eat a thing. His next doctor's appointment is on Tuesday... hoping to learn more.

Your help in offering insight into my questions would be greatly appreciated.
Kim