Possible stomach cancer

My almost 81 YO mother has been through all the tests - first was diagnosed with a blood clot in her lung then more tests showed spots in both lymph nodes, stomach annd lung- biopsy from Lymph node showed it's a GI cancer - Her oncologist thinks it is stomach so we are headed this AM to get endoscopy then hopefully at Tuesday Dr appt we will know the full diagnosis.. she has been overall healthy all her life so this is a shock but not really too surprised as most people her age seem to get cancer..! Not many symptoms at all- besides losing weight /no appetite but that has picked back up since we found out so she was thinking it was nerves.... I've read several posts on here .. I will continue to read and try to learn what will happen next ....