Randomized Multicenter Phase II Trial of a Biweekly Regimen of Fluorouracil and Leucovorin (LV5FU2), LV5FU2 Plus Cisplatin, or LV5FU2 Plus Irinotecan in Patients With Previously Untreated Metastatic Gastric Cancer: A Fédération Francophone de Cancérologie Digestive Group Study—FFCD 9803 | Synapse