In addition, we also found that PTGS2, enriched in the smoking-related subtypes, was primarily involved in inflammatory/oxidative responses pathways and showed a negative correlation with the SCFAs-producing genus Lachnospiraceae NK4A136 group, indicating that smoking could attenuate the anti-inflammatory action and thus increase the CRC risk by reducing SCFAs-producing bacteria in abundance. The gene discussed is PTGS2; the disease is colorectal carcinoma.