Hello Goldie123; welcome to the forum.  So difficult to have to make decisions when your mother in law has just had the shock of this diagnosis.  She needs to talk with the oncologist; make a list of questions before she goes to the appointment and take someone with her so nothing is forgotten and answers to her questions are written down.  Obviously the decision lies with your mother in law; she will hopefully be in a better position to make the decision - she doesn't have to make it on the spot - when she has the information she needs.  Questions like what difference to her life span will treatment make; what are the likely side effects: only she can weigh up the pros and cons and make that decision ultimately.  Sorry if I make this sound purely clinical - I realise this is something traumatic and life-shattering.  My best wishes to you all.  Annie