KRAS and neoplasm: Although the 1-mm resection margin is currently considered the gold standard for an R0 resection, this is not without debate.25,26,27,28,29,30 Some retrospective studies have suggested that tumor debulking (0 mm margin) might suffice, whereas in some cases, more margin is required to avoid local tumor recurrence,26,31 especially for KRAS-mutated primary tumors.