My husband also had lichen planus for many years and was told by specialist at Dental School that it rarely became cancerous. As luck would have it, his was one of the cases where it did. I guess the problem is that erosive ulcers can be fairly frequent with this condition and one tends to "live with it" and not be as vigilant at having them checked out. He did have some ointment to use on the ulcers that helped them heal, sorry I can no longer remember the name of it, maybe one of our dentists on the forum will chime in with the name. Since you have had one cancer diagnosis I am sure you are being checked frequently and will hopefully avoid any advanced scc.