My grandpa was diagnosed with stomach cancer.they just found out also that it has spread to his liver, lungs, brain, spleen and lymph nodes. how long?

Depends: The question is how well will this respond to radiation / chemotherapy and whether they are worth trying. Untreated, the best i can tell you is, "less than a year." with today's targeted therapies especially -- and these are starting to get used in stomach cancer -- all bets are off. Enjoy whatever amount of time you have left, knowing the uncertainty.

Hang in there: Your grandfather has stage 4 stomach cancer. Treatment can't cure this. Perhaps time can be extended by chemotherapy. With such widespread disease, ask him to get the opinion of his oncologist. See what side effects the drugs have. Balance that against the benefit. Care directed at comfort and dignity is a good option. Sorry, but i can't give answers to "how long" questions.

Sorry to hear that.: Unfortunately, we do not yet have curative treatment for stomach cancer that has spread. Hopefully some day! it is always hard to know exactly how long someone will live with this disease. I usually give a range from a few to many months. There are many treatments that can be done to help alleviate pain and suffering.