Table 3.

Characteristics of included studies

	Study	Platform	Study design	Sample Extraction	Type of samples	Sample size
1	Nishiumi et al. (26)	GC/MS	Case series	Extraction buffer: Methanol Water Chloroform	Serum	Training set CRC patients n = 60 • Stage 0: 12, Stage I: 12, Stage II: 12, Stage III: 12, Stage IV: 12 Control: • Healthy control n = 60 Validation set • CRC patients n = 59 • Stage 0: 15, Stage I: 11, Stage II: 13, Stage III: 11, Stage IV: 19 Control: • Healthy control n = 63
2	Vahabi et al. (27)	1H NMR	Case series	Extraction buffer: Deuterated water	Serum	CRC patients n = 16 • Stage 0–I: 8, Stage II–IV: 8
3	Uchiyama et al. (28)	CE-TOFMS	Case series	Extraction buffer: Methanol Chloroform	Serum	CRC patients n = 56 • Stage I: 14, Stage II: 14, Stage III: 14, Stage IV: 14 Control: • Healthy control n = 59
4	Lin et al. (15)	1H NMR	Case series	No extraction	Faecal	100 fecal sample • 68 CRC, Stage I/II: 20, Stage III: 25, Stage IV: 23 • 32 healthy
5	Wang et al. (29)	1H NMR	Case series	Extraction buffer: Methanol Chloroform	Colon Tissue	CRC patients n = 127 • Stage I: 35, Stage II: 37, Stage III: 37, Stage IV: 18 Control: • Adjacent non-tumour tissue n = 43
6	Mirnezami et al. (30)	HR-MAS NMR	Prospective observational study	Extraction buffer: Deuterated water	Colorectal mucosa	CRC patients n = 44 • Stage I/II: 12, Stage III: 20 • Stage IV: 12
7	Williams et al. (31)	UPLC TWIMMS	Case series	Extraction buffer: Acetonitrile Water Formic acid	Rectal Tissue	CRC patients n = 9 • Stage I: 1, Stage II: 3, Stage III: 5, Stage IV: 1 Control: • Adjacent non-tumour tissue n = 9
8	Tian et al. (32)	1H HRMAS NMR GC-FID/MS (analysed the fatty acid)	Case series	Extraction buffer: Deuterium oxide Methanol	Colon and Rectal Tissue	CRC patients n = 50: • 16 colon cancer • 34 rectal cancer Stage I: 16, Stage II: 12, Stage III: 17, Stage IV: 5 Control: • Adjacent non-involve tissue (ANIT) n = 50