I'm not sure what type of search you did on the internet and I am NOT a doctor, but when I googled your symptoms, this is what I came up with: not cancer but Epithelial Hyperplasia
here is a link to a description of it
Epithelial Hperplasia
Perhaps that is why your doctors are "confused" since you are asking them about cancer.
You did not get a response because you asked for a response from someone who had your symptoms. Apparently none of us with cancer have had just thickening with no lesions, no tumors and nothing to biopsy. That should be comforting to you. again, I found nothing on the internet that indicated cancer with what your described so I guess I agree with your doctors about "no clinical symptoms" and am equally puzzled.
Charm