Triplet (FOLFOXIRI) versus doublet (FOLFOX or FOLFIRI) backbone chemotherapy as first-line treatment of metastatic colorectal cancer : a systematic review and meta-analysis - Marques, Rui Pedro; Duarte, Gonçalo Silva; Sterrantino, Carmelo; Pais, Helena Luna; Quintela, António; Martins, Ana Paula; Costa, João (2017)