In left-sided tumours, a clear difference between the subtypes in efficacy of anti-EGFR with the different backbones was observed, with CMS2/3 having a significant PFS benefit from the addition of anti-EGFR with both chemotherapy backbones (CAPOX/FOLFOX HR 0.57, 95% CI 0.36–0.96, P = 0.034; Irinotecan HR 0.44, 95% CI 0.26–0.75, P = 0.003). This evidence concerns the gene EGFR and neoplasm.