@gorkii the presentation is archived at the top of this page. Radhika Dhamija answers your question 6:30' minutes into the presentation. The audio is a bit difficult to understand, so I have paraphrased her response here:
"We can consider genetic testing for stomach cancer when the age and onset or presentation is unusual and there is a family history of cancer. For example, it could be considered in a young person who is otherwise healthy and there is a family history of other cancers. However, most stomach cancers are not genetically predisposed."