Hi,
Your concerns are valid. Lung
cancer is afterall, the biggest cause of
cancer mortality. For this post, I can only work with the stage information, your doctor likely has better estimates.
Much of the answer here depends on how much the disease is affecting her daily living. If she stays in bed most of her waking hours, then treatment may only make an impact on symptom improvement. If she is able to maintain a fairly active lifestyle – then treatment may help extend survival .