Our aims were: (a) to investigate the differences in the mucosal colon microbiome between healthy and CRC subjects, with and without the additional contribution of the overweight/obesity co-morbidity; (b) to explore if tumor-associated microorganisms are also present in the nearby non-cancerous region; and (c) to look for any association between significantly CRC-associated bacteria and the systemic inflammation, as assessed by CCL2 circulating levels. This evidence concerns the gene CCL2 and neoplasm.