I’d like to hear the results of your PET, which is not diagnostic for cancer. Just cells that are burning sugar faster than others. For sure cancer does this, but so does inflammation in cells. But there is a reason that radiation is used after surgery even w clean margins. (Except very small stage ones) There are cells outside of the margin likely, that are not malignant but dysplastic, so half way to becoming cancer. It’s a product of field cancerization as many SCC are not completely focal. It may take months or a year for them to go completely to the dark side. Washing an area around the original cancer with radiation ensures they are also killed.