I don't know all your particular's, but negative margins can have different meanings to different doctors in size, 1cm, 5mm, etc. and all not agree either what is considered clear or not. Maybe it was determined from the start to probably do radiation, and some like to take you one step at a time until knowing further after surgery, which can tell the tumor Size, location, thickness, midline, other negative prognostic factors like PNI, LVI, which effects wether radiation or chemoradiation may be needed, and further histology from the biopsy to come, and probably only have the frozen section biopsy done during surgery. Personally, I would want radiation to kill any microscopic cancer, if thats what was recoomended. See about a 2nd opionion, but yiu need all your files, and radiation should start bewtwen 4-6 weeks, idelly, depending on healing. You definately don't want to do this twice, which outcome is not that good. Glad your surgery went well.