Table 1.

Excluded studies

Study	Reason for Exclusion
Bedin et al. (17)	Proteomics study
Chen et al. (18)	Analysis did not take into account the different stages
Farshidfar et al. (19)	Result did not include list of metabolites of different stages
Jimenez et al. (20)	Sampling method unclear
Qiu et al. (21)	Study did not involve CRC progression
Aleksandrova et al. (22)	This is a longitudinal cohort study
Wang et al. (23)	Study only involved in early CRC
Jordan et al. (24)	Study did not involve in different stages of CRC
Lin et al. (25)	Article in Chinese