Mom has stomach cancer

We found out the day before we buried my grandfather that my mother has stomach cancer.  We are in the very early stages of all of this but my mother is comforted that "as far as they can tell" it is confined to the stomach and has not spread to other organs.  Not sure what that means but this has been very difficult.  My things I read is that stomach cancer is a painful process and most people lose the battle.  I am trying very hard to rely on God and rest in his assurance that if she does not win this battle she will be in heaven with him.  She is suppose to go this week to talk with the chemo dr and decide a course of treatment.  I feel like what I read is that seldom is stomach caught in time.  If you have any insight as to how to deal with this I would greatly appreciate it.  Prior to this, I have been caught up in my own little world and never really gave cancer a thought.  My grandfather had it and was cured.  I am truly sorry I was so not in tune with how many people suffer from this disease.  I promise I will pray for each family here and never again take health issues so lightly. You all have my love and prayers and may God somehow get us through this journey together.