Sorry to hear about your Mums cancer. I myself have been to the Issels clinic in Tijuana, I have nothing but praise for the treatment I received. I have lung cancer and it has spread into the lymph system. My last scan showed that things were drastically reducing. This is all due to Issels as nothing was offered to me in the UK apart from pallative care. I owe my life to Issels. If I was you I would given them a ring, you will find the number on their website. They can give you all the details of cost etc. and one thing they are very truthful on the phone. Oasis is a little bit cheaper but they will explain all treatments available.
Hope this helps, Carolyn