Adding immunotherapy to standard treatment both before and after surgery significantly improved outcomes for people with gastric and gastroesophageal adenocarcinoma (G/GEA), according to experts from Memorial Sloan Kettering Cancer Center (MSK). Results from the MATTERHORN trial, a global phase three study, were presented today at the annual American Society of Clinical Oncology meeting and simultaneously published in the New England Journal of Medicine (NEJM).