Comparison of general clinical features
The study population was divided into training set and validation set according to 7:3. There were 4091 healthy controls and 2552 GC patients in the training set, 1731 healthy controls and 1098 GC patients in the validation set. There was no significant difference in the basic clinical characteristics between the training set and the validation set (P > 0.05, Table 1).
Table 1. The clinicopathological characteristics of the study population, number (%)
Characteristics
|
Training set
(N=6643)
|
Validation set
( N=2829)
|
t/χ2
|
P
|
Healthy controls
|
4091
|
1731
|
|
|
Age, y
Mean±standard deviation
Gender
Male
Female
ABO blood group
A
B
O
AB
Patients with GC
Age, y
Mean±standard deviation
Gender
Male
Female
ABO blood group
A
B
O
AB
TNM stage
I
II
III
IV
Differentiation
Well differentiation
Well and middle differentiation
Middle differentiation
Middle and low differentiation
Low differentiation
Tumor site
Pylorus
Gastric body
Antrum
Whole stomach
Lymphatic metastasis
N0
N1-3
Remote metastasis
M0
M1
Pathological stage
Early stage
Advanced stage
|
50±10
2134(52.2)
1957(47.8)
1178(28.8)
1259(30.8)
1224(29.9)
430(10.5)
2552
58±11
1896(74.3)
656(25.7)
818(32.1)
769(30.1)
714(28.0)
251(9.8)
716(28.1)
510(20.0)
1202(47.1)
124(4.9)
62(2.4)
57(2.2)
509(19.9)
316(12.4)
1608(63.0)
282(11.1)
838(32.8)
1283(50.3)
149(5.8)
1568(61.4)
984(38.6)
1883(73.8)
669(26.2)
601(23.6)
1951(76.4)
|
50±10
935(54.0)
796(46.0)
519(30.0)
525(30.3)
519(30.0)
168(9.7)
1098
58±11
823(75.0)
275(25.0)
358(32.6)
320(29.1)
302(27.5)
118(10.7)
335(30.5)
203(18.5)
515(46.9)
45(4.1)
43(3.9)
20(1.8)
222(20.2)
127(11.6)
686(62.5)
125(11.4)
349(31.8)
547(49.8)
77(7.0)
645(58.7)
453(41.3)
818(74.5)
280(25.5)
277(25.2)
821(74.8)
|
1.673
1.437
0.176
1.017
3.450
7.001
2.079
2.343
0.203
1.183
|
0.813
0.196
0.697
0.915
0.675
0.797
0.327
0.136
0.556
0.126
0.652
0.277
|
Tumor marker levels and blood group distribution
In both the training and validation sets, the level of tumor markers in the GC group was significantly higher than that in the healthy control group, and the difference was statistically significant (P < 0.05), as shown in Table 2. The distribution of blood group in GC group was: A > B > O > AB, while that in healthy control group was: B > O > A > AB. There were statistically significant differences in ABO distribution constituent ratios in the whole population (χ2=10.920, P =0.012, Table 3) and the training set (χ2=8.495, P =0.037, Table 3).
Table 2. Differences in tumor marker levels between GC group and healthy controls, median (IQR)
|
Patients with GC
|
Healthy subjects
|
Z
|
P
|
CEA(ng/ml)
Training set
Validation set
|
3.875(2.250,105.000)*
4.280(2.378,106.250)
|
1.620(1.080,2.330)
1.600(1.030,2.360)
|
-40.048
-27.908
|
.000
.000
|
CA199(U/ml)
Training set
Validation set
|
6.290(1.733,20.075)
6.305(1.850,15.650)
|
9.050(6.120,13.590)
8.620(5.890,12.890)
|
-13.194
-7.871
|
.000
.000
|
CA125(U/ml)
Training set
Validation set
AFP(ng/ml)
Training set
Validation set
|
5.505(1.560,8.868)
5.790(1.578,8.750)
3.720(2.590,27.095)
3.730(2.520,17.550)
|
10.180(7.680,13.590)
10.140(7.630,13.660)
2.880(2.100,3.910)
2.830(2.050,3.800)
|
-35.102
-22.221
-23.428
-15.612
|
.000
.000
.000
.000
|
CA72-4(U/ml)
Training set
Validation set
|
4.580(2.022,47.600)
4.620(2.000,44.615)
|
1.610(0.980,2.960)
1.680(1.020,3.040)
|
-32.623
-20.392
|
.000
.000
|
Note: *Values are expressed as medians and interquartile ranges.
Table 3. Distribution of ABO blood groups
|
Patients with GC
|
Healthy subjects
|
χ2
|
P
|
A
Training set
Validation set
B
Training set
Validation set
O
Training set
Validation set
|
818(32.1)
358(32.6)
769(30.1)
320(29.1)
714(28.0)
302(27.5)
|
1178(28.8)
519(30.0)
1259(30.8)
525(30.3)
1224(29.9)
519(30.0)
|
8.495
3.949
|
0.037
0.267
|
AB
Training set
Validation set
|
251(9.8)
118(10.7)
|
430(10.5)
168(9.7)
|
|
|
Diagnostic value of single tumor marker and combined detection for GC
The AUC of the five tumor markers ranged from 0.594-0.797, with a sensitivity of 32.22%-66.99%, which was at a low level (Table 4, Figure 1). The combined detection of tumor markers can improve its sensitivity and specificity. Compared with the combined detection of 5 tumor markers, the combination of type B and AB blood with 5 tumor markers can improve the diagnostic value of GC. The B blood group (AUC=0.936, 95%CI 0.927-0.945, P < 0.0001) combined with swelling mark detection was higher than that of swelling mark detection alone, and the difference was statistically significant. There was no significant difference in the AUC of AB blood (AUC=0.928, 95%CI 0.909-0.943, P =0.0566), but the P value was at the critical value of the test level (Table 5).
Table 4. Diagnostic value of single tumor marker in patients with GC
TM
|
AUC
|
95%CI
|
TPR(%)
|
TNR(%)
|
Youden index
|
CEA
|
0.797
|
0.789-0.806
|
66.99
|
82.05
|
0.4904
|
CA199
|
0.594
|
0.584-0.604
|
34.05
|
91.64
|
0.2569
|
CA125
AFP
CA724
|
0.753
0.672
0.734
|
0.744-0.762
0.662-0.681
0.725-0.743
|
44.68
32.22
42.79
|
99.07
99.71
99.02
|
0.4376
0.3193
0.4182
|
Note: TM: tumor maker, CI: confidence interval, TPR: true positive rate, TNR: true negative rate
Table 5. Combined diagnosis compared with stratified combined diagnosis
TM
|
AUC
|
95%CI
|
TPR (%)
|
TNR (%)
|
Youden index
|
Z
|
P
|
TM
A+TM
|
0.917
0.908
|
0.912-0.923
0.897-0.919
|
78.82
80.53
|
97.39
95.99
|
0.7621
0.7652
|
116.750
60.185
|
<0.0001
<0.0001
|
B+TM
O+TM AB+TM
|
0.936
0.911
0.928
|
0.927-0.945
0.900-0.921
0.909-0.943
|
80.17
79.92
78.32
|
95.85
96.90
98.33
|
0.7602
0.7682
0.7665
|
81.086
57.473
42.531
|
<0.0001
<0.0001
<0.0001
|
Diagnostic value of blood group combined with single serum tumor marker for GC
Stratified ABO blood group, in the training set, it was found that compared with the unstratified group, the stratified type A blood group could improve the diagnostic value of CA199, CA125, AFP and CA724 for GC, but the difference was not statistically significant (Table 6, Figure 2a). Blood type B could improve the diagnostic value of CEA (AUC=0.847, 95%CI 0.831-0.863, P=0.0081) in GC, and the difference was statistically significant (Table 6, Figure 2b). Blood type O could improve the diagnostic value of CA199 and CA724 for GC, and CA199 (AUC=0.611, 95%CI 0.589-0.633, P=0.0469) had statistical significance, while CA724 had no statistical difference (Table 6, Figure 2c). AB blood group can improve the diagnostic value of CEA, CA199, CA125 and AFP in GC, but no statistical difference was found (Table 6, Figure 2d). The same method was used to explore the diagnostic value of ABO blood group combined with tumor markers for GC in the validation set. It was found that compared with unstratified blood group, type A blood group could improve the diagnostic value of CA724 for GC, but the difference was not statistically significant (Table 7, Figure 3a). Consistent with the results of the training set, type B blood could improve the diagnostic value of CEA (AUC=0.857, 95%CI 0.832-0.880, P < 0.0001) for GC, and the difference was statistically significant (Table 7, Figure 3b). Type O blood can improve the diagnostic value of AFP in GC, but the difference was not statistically significant (Table 7, Figure 3c). AB blood group can improve the diagnostic value of CEA, CA199 and AFP in GC, but no statistical difference was found (Table 7, Figure 3d). In addition, the overall study population was stratified according to ABO blood group, it was found that in addition to type B blood (AUC=0.850,95%CI 0.837-0.863, P =0.0006) and type AB blood (AUC=0.837,95%CI 0.812-0.860, P =0.0439) could also improve the diagnostic value of CEA for GC, as shown in Figure 4.
Table 6. Diagnostic Value of ABO blood group combined with tumor markers for GC (training set)
TM
|
AUC
|
95%CI
|
TPR (%)
|
TNR (%)
|
Youden index
|
Z
|
P
|
A
|
|
|
|
|
|
|
|
CEA
|
0.740
|
0.720-0.759
|
48.29
|
98.22
|
0.4651
|
18.433
|
<0.0001
|
CA199
CA125
AFP
CA724
|
0.601
0.762
0.677
0.742
|
0.579-0.622
0.743-0.780
0.656-0.698
0.722-0.761
|
35.09
45.23
31.54
42.42
|
90.32
99.24
99.99
99.15
|
0.2541
0.4470
0.3754
0.4157
|
7.083
21.343
14.276
19.966
|
<0.0001
<0.0001
<0.0001
<0.0001
|
B
|
|
|
|
|
|
|
|
CEA
|
0.847
|
0.831-0.863
|
77.63
|
76.73
|
0.5436
|
36.781
|
<0.0001
|
CA199
|
0.571
|
0.549-0.593
|
31.21
|
92.53
|
0.2374
|
4.787
|
<0.0001
|
CA125
AFP
CA724
O
CEA
CA199
CA125
AFP
CA724
AB
CEA
CA199
CA125
AFP
CA724
|
0.747
0.664
0.728
0.777
0.611
0.749
0.667
0.748
0.830
0.616
0.779
0.682
0.725
|
0.728-0.766
0.643-0.685
0.708-0.747
0.757-0.795
0.589-0.633
0.730-0.769
0.646-0.688
0.728-0.767
0.799-0.857
0.578-0.653
0.746-0.810
0.645-0.716
0.690-0.758
|
47.98
30.82
43.56
59.38
40.06
44.68
34.03
46.36
79.68
32.67
71.71
36.25
55.38
|
98.73
99.76
99.99
87.83
92.08
97.63
99.59
97.88
73.72
95.81
77.21
98.84
85.81
|
0.4671
0.3058
0.4356
0.4721
0.3213
0.4231
0.3363
0.4423
0.5340
0.2848
0.4892
0.3509
0.4119
|
19.100
12.76
17.802
21.969
7.283
18.572
12.695
19.361
18.195
4.562
12.824
8.000
9.978
|
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
|
Table 7. Diagnostic Value of ABO blood group combined with tumor markers for GC (validation set)
TM
|
AUC
|
95%CI
|
TPR (%)
|
TNR (%)
|
Youden index
|
Z
|
P
|
A
|
|
|
|
|
|
|
|
CEA
|
0.782
|
0.753-0.809
|
52.79
|
99.61
|
0.5241
|
15.568
|
<0.0001
|
CA199
CA125
AFP
CA724
|
0.576
0.741
0.658
0.735
|
0.542-0.609
0.711-0.770
0.626-0.689
0.705-0.764
|
50.28
47.77
33.80
45.81
|
73.32
94.61
99.81
98.84
|
0.2350
0.4237
0.3361
0.4465
|
3.476
12.431
8.063
12.698
|
<0.0001
<0.0001
<0.0001
<0.0001
|
B
|
|
|
|
|
|
|
|
CEA
|
0.857
|
0.832-0.880
|
90.31
|
67.05
|
0.5736
|
26.005
|
<0.0001
|
CA199
CA125
AFP
CA724
|
0.587
0.771
0.664
0.749
|
0.553-0.621
0.741-0.799
0.631-0.696
0.718-0.778
|
38.75
46.56
31.25
41.56
|
85.90
99.81
97.52
99.05
|
0.2465
0.4637
0.2877
0.4067
|
3.911
14.067
8.186
13.219
|
<0.0001
<0.0001
<0.0001
<0.0001
|
O
|
|
|
|
|
|
|
|
CEA
|
0.781
|
0.751-0.808
|
69.21
|
77.84
|
0.4705
|
14.858
|
<0.0001
|
CA199
CA125
AFP
CA724
|
0.592
0.750
0.695
0.696
|
0.558-0.626
0.719-0.779
0.662-0.726
0.663-0.727
|
35.76
57.62
39.40
43.05
|
86.90
83.82
94.99
98.84
|
0.2266
0.4143
0.3439
0.4189
|
4.031
12.414
9.754
8.938
|
<0.0001
<0.0001
<0.0001
<0.0001
|
AB
|
|
|
|
|
|
|
|
CEA
|
0.852
|
0.805-0.891
|
74.58
|
85.12
|
0.5970
|
13.831
|
<0.0001
|
CA199
CA125
AFP
CA724
|
0.612
0.696
0.695
0.711
|
0.553-0.669
0.639-0.748
0.638-0.748
0.655-0.763
|
46.61
44.92
33.90
46.61
|
86.90
97.62
99.99
94.05
|
0.3351
0.4253
0.3390
0.4066
|
2.955
5.391
5.926
6.274
|
<0.0001
<0.0001
<0.0001
<0.0001
|