It's likely a fistula. (radiated skin has trouble healing) They should pack it and treat it. So it heals - sometimes they need surgical intervention and a new graft. This will take time because it has to heal, while her cancer grows. A radiation dr. Could tell you better if rads can be given with the hole- truthfully it depends on where her other cancers are and where they'd focus the beam. What I would do is ask them to surgically remove as much cancer as possible., repair what they can then do radiation, usually 6 weeks after - but in that time hopefully she will heal and get preparations for radiation underway. You need to find a good medical team that can work together. Good luck.