Radiation is accumulative in your lifetime. As a patient hearing that they are considering bracytherapy etc. which is low dose and very localized, leads me to believe that her levels of exposure are getting maxed out. Considering the wide range of areas in which she has this, this very localized treatments are likely not going to be extremely effective since the radioactive bracytherapy seed/bead is only designed to reach a local spot. You are right though that chemo for localized oral cancers has not been greatly effective. I think that you have misunderstood something about gene therapies, which are mostly clinical trials right now. They are not toxic and that is why they are racing in this direction with so many different clinical trials on different gene therapies. As cancer itself is a series of genetic mutations, in the long run, these therapies show the greatest promise.