sorry to hear about your mom and I can feel your concern.
Non resolving pneumonia
should be worked up and malignancy is one cause of this...I don't know to what extent it was pneumonia radiologically and was it followed up properly or not.
A significant weight loss
should prompt a clinician to aearch for cancer.
Stage 4 lung cancer
means it has metastasized or spread to different parts of the body including liver
, adrenals, bone, brain etc....and that would have been cause of pathological frature you stated.
In your case it is yet to find out that where was the primary ....was it in alimentary system because there were symptoms of GI disturbance or was it in the lung itself and has spread to the two parts vice versa.
Now regarding the treatment stage 4 lung cancer requires Only palliative treatment i.e palliative chemotherapy
can be given and that too depends on the general condition of the patient called performance scores.
The cancer might have been there well before the symptoms have started to come........
Had it been diagnosed early incidentally or planned workup then it might have been possible to atleast palliate the symptoms but then also survival would not have been too much......
may her soul rest in peace..