Lung cancer that has moved to the bone

My Mom has just been told that her cancer is now growing and is in the bone. Two years ago she had her left lung removed, she had her chemo and all was good. In July they found a spot "on" one of her left ribs and we started chemo again. Here it is November and now they are saying that it is "in" the bone and the lymph nodes around the area. Can anyone tell me what to expect??? I am so very worried about my Mom!!!!!
Thanks,
Grakie