I was just diagnosed with pharyngeal thrush (and possible esophageal thrush) yesterday, but I do not have AIDs, diabetes, Or GERD. My doctor took a throat sample to verify it is a yeast infection, and if so, she wants me to have an upper GI endoscope done as I feel terrible and besides the awful sore throat, have nausea, heartburn etc which she believes means there is yeast in the esophagus as well. Is cancer the only other possible root cause?