“…It is speculated that factors beyond clinical stage, tumor genomics and germline polymorphism etc (Pezzolo et al, 2015;Dayde et al, 2017) may influence therapeutic responses and toxicities, including host factors such as differential composition of the patients' gut microbiome (Qin et al, 2010;Arumugam et al, 2011;Koren et al, 2013). Several species of commensal bacteria were shown to play potential roles in colorectal carcinogenesis (Yu et al, 2017;Garrett, 2019;Thomas et al, 2019;Wirbel and Pyl, 2019;Wong and Yu, 2019;Ternes et al, 2020;Yang et al, 2020). More strikingly, commensal bacteria were shown to modulate cancer responses to therapy, including chemotherapy and immunotherapy (Iida et al, 2013;Viaud et al, 2013;Roy and Trinchieri, 2017;Gopalakrishnan and Spencer, 2018;Matson et al, 2018;Routy and Le Chatelier, 2018) and to be correlated with toxicities of chemotherapy or radiotherapy (Husebye et al, 1995;Crawford and Gordon, 2005;Manichanh et al, 2008;Wedlake et al, 2008;Wallace et al, 2010;Nam et al, 2013;Ferreira et al, 2014;Wallace et al, 2015;Wang et al, 2015;Reis Ferreira et al, 2019).…”