In both the CRC group and the adenoma group, the comparison of clinical characteristics between the two subtypes showed that serum carcinoembryonic antigen (CEA) and alkaline phosphatase (ALP) of type II enterotype (termed smoking-related enterotype) were significantly lower than those of type I enterotype (termed non-smoking-related enterotype) (Supplementary file Tables 1 and 2). Here, CEACAM5 is linked to adenoma.