Serum M2-pyruvate kinase: A promising non-invasive biomarker for colorectal cancer mass screening

Table 1 Basic characteristics of study population for the value of serum pyruvate kinase Isoenzyme M2 and carcinoembryonic antigen in colorectal cancer mass screening in Hangzhou, China, 2006-2008 (mean ± SD)

Colorectal lesion	n	Gender		Age (yr)	M2-PK (U/mL)	CEA (ng/mL)
		Male	Female
Colorectal cancer
Stage I and II	55	53	40	59.17 ± 10.71	13.10 ± 12.07	5.74 ± 7.49
Stage III	38				14.75 ± 13.39	5.68 ± 5.43
Advanced adenoma	41	25	16	60.17 ± 7.78	8.58 ± 7.65	2.68 ± 1.43
Adenoma	137	68	69	60.34 ± 8.16	6.70 ± 6.97	2.58 ± 3.74
Nonadenomatous polyp	47	25	22	59.04 ± 8.08	5.13 ± 3.73	2.55 ± 2.09
IBD	7	1	6	57.43 ± 7.16	2.51 ± 1.94	1.71 ± 0.91
Normal	158	56	102	57.15 ± 7.96	2.96 ± 2.17	1.98 ± 1.02

IBD: Inflammatory bowel disease; M2-PK: M2-pyruvate kinase; CEA: Carcinoembryonic antigen.

Table 2 The area under the receiver operating characteristic curve and 95% confidence interval of serum pyruvate kinase isoenzyme M2 in U/mL and carcinoembryonic antigen in ng/mL in diagnosing colorectal lesions in colorectal cancer mass screening in Hangzhou, China, 2006-2008

Colorectal lesion	Test	AUC	SE	P-value	95% CI
CRC stage I and II	CEA	0.70	0.04	< 0.0001	0.62-0.79
	M2-PK	0.89	0.03	< 0.0001	0.84-0.94
CRC stage III	CEA	0.73	0.05	< 0.0001	0.63-0.83
	M2-PK	0.89	0.03	< 0.0001	0.84-0.94
Advanced adenoma	CEA	0.63	0.05	0.01	0.53-0.73
	M2-PK	0.81	0.04	< 0.0001	0.74-0.86
Adenoma	CEA	0.54	0.03	0.28	0.47-0.60
	M2-PK	0.69	0.03	< 0.0001	0.64-0.76
Nonadenomatous polyp	CEA	0.58	0.05	0.09	0.48-0.68
	M2-PK	0.69	0.04	< 0.0001	0.62-0.78
Inflammatory bowel disease	CEA	0.41	0.10	0.40	0.21-0.61
	M2-PK	0.42	0.10	0.40	0.21-0.63

AUC: Area under the receiver operating characteristic curve; CRC: Colorectal cancer; CI: Confidence interval; M2-PK: M2-pyruvate kinase; CEA: Carcinoembryonic antigen.

Table 3 Diagnostic sensitivity and specificity in percentage at 95% confidence interval of serum M2-pyruvate kinase using various cut-off value settings for different colorectal lesions compared with 158 normal people in colorectal cancer mass screening in Hangzhou, 2006-2008 (95% CI)

M2-PK (U/mL)	Colorectal cancer		Advanced adenoma		Adenoma		Non-adenomatous polyp
	Sensitivity	Specificity	Sensitivity	Specificity	Sensitivity	Specificity	Sensitivity	Specificity
2.00	100.00 (100.00-100.00)	40.51 (32.85-48.16)	95.12 (88.53-100.00)	40.51 (32.85-48.16)	82.48 (76.12-88.85)	40.51 (32.85-48.16)	82.98 (72.23-93.72)	40.51 (32.85-48.16)
2.50	94.62 (90.04-99.21)	55.06 (47.31-62.82)	85.37 (74.55-96.18)	55.06 (47.31-62.82)	71.53 (63.98-79.09)	55.06 (47.31-62.82)	76.60 (64.49-88.70)	55.06 (47.31-62.82)
3.00	91.40 (85.70-97.10)	65.19 (57.76-72.62)	75.61 (62.46-88.75)	65.19 (57.76-72.62)	61.31 (53.16-69.47)	65.19 (57.76-72.62)	65.96 (52.41-79.50)	65.18 (57.76-72.62)
3.50	87.10 (80.28-93.91)	68.99 (61.78-76.20)	73.17 (59.61-86.73)	68.99 (61.78-76.20)	56.93 (48.64-65.23)	68.99 (61.78-76.20)	55.32 (41.11-69.53)	68.99 (61.78-76.20)
4.00	81.72 (73.87-89.58)	74.05 (67.22-80.89)	65.85 (51.34-80.37)	74.05 (67.22-80.89)	49.64 (41.26-58.01)	74.05 (67.22-80.89)	48.94 (34.64-63.23)	74.05 (67.22-80.89)

M2-PK: M2-pyruvate kinase.

Table 4 Positive predictive value and negative predictive value in percentage at 95% confidence interval of serum M2-pyruvate kinase using various cut-off value settings for different colorectal lesions compared with 158 normal people in colorectal cancer mass screening in Hangzhou, China, 2006-2008 (95% CI)

M2-PK (U/mL)	Colorectal cancer		Advanced adenoma		Adenoma		Nonadenomatous polyps
	PPV	NPV	PPV	NPV	PPV	NPV	PPV	NPV
2.00	49.73 (42.57-56.90)	100.00 (100.00-100.00)	29.32 (21.59-37.06)	96.97 (92.83-100.00)	54.59 (47.81-61.37)	72.73 (63.42-82.03)	29.32 (21.59-37.06)	88.89 (81.63-96.15)
2.50	55.35 (47.62-63.07)	94.57 (89.93-99.20)	33.02 (24.07-41.97)	93.55 (88.56-98.54)	57.99 (50.55-65.43)	69.05 (60.98-77.12)	33.64 (24.69-42.60)	88.78 (82.23-95.03)
3.00	60.71 (52.62-68.80)	92.79 (87.98-97.60)	36.05 (25.90-46.19)	91.15 (85.91-96.39)	60.43 (52.30-68.56)	66.03 (58.59-73.46)	36.05 (25.90-46.19)	86.55 (80.43-92.68)
3.50	62.31 (53.98-70.64)	90.08 (84.76-95.41)	37.97 (27.27-48.68)	90.83 (85.67-96.00)	61.42 (52.95-69.88)	64.88 (57.66-72.10)	34.67 (23.90-45.44)	83.85 (77.52-90.17)
4.00	64.96 (56.31-73.60)	87.31 (67.22-80.89)	39.71 (28.08-51.34)	89.31 (84.02-94.60)	62.39 (53.29-71.48)	62.90 (55.96-69.85)	35.94 (24.18-47.69)	82.98 (76.78-89.18)

M2-PK: M2-pyruvate kinase; PPV: Positive predictive value; NPV: Negative predictive value.