Thank you for the query.
As stomach cancer
can give no symptoms at all or gives nonspecific symptoms like abdominal pains, weakness, nausea
it is very hard to detect it in an early stage. And it is told that about 20% of it can be hereditary. According to this facts it is very hard to tell you if you should be afraid of this cancer or not.
The best way to deal with this problem is to have upper GI endoscopy
wont visualize early stage of stomach cancer). You can also have checked Ca 19-9 marker from time to time.
Hope this will help.