Just found out my mum has cancer

To say I am devestated does not describe how I am feeling. We found out by pure chance the other day that my mum has cancer.  It has come totally out of the blue as she was being x-rayed for a broken arm and they found a tumour in her arm.. It has gone further in that by the time her CT was completed they found another tumour in her pelvis.  How on earth can she have gone from being fit and healthy one day to finding out she has secondary cancer the next.  The worst thing ever is that they have not located the primary source yet, although they think it is in her womb.  I feel like my whole world has been turned upside down and has come crashing down in the space of a week.   All I can think about is how far advanced it must be and I am totally petrified that she is already beyond help.. How can this happen. x