Clinicopathologic Characteristics
Table 1 丨Clinicopathologic features of colon MAC in the train set and the internal validation set
Characteristic
|
train set, N = 1,079
|
validation set, N = 460
|
p-value
|
Age
|
|
|
0.609
|
<80
|
772 (72%)
|
335 (73%)
|
|
≥80
|
307 (28%)
|
125 (27%)
|
|
Sex
|
|
|
0.899
|
Female
|
548 (51%)
|
232 (50%)
|
|
Male
|
531 (49%)
|
228 (50%)
|
|
Race
|
|
|
0.301
|
Black
|
87 (8.1%)
|
30 (6.5%)
|
|
Other
|
120 (11%)
|
43 (9.3%)
|
|
White
|
872 (81%)
|
387 (84%)
|
|
T
|
|
|
0.460
|
T1
|
38 (3.5%)
|
20 (4.3%)
|
|
T2
|
136 (13%)
|
47 (10%)
|
|
T3
|
611 (57%)
|
272 (59%)
|
|
T4
|
294 (27%)
|
121 (26%)
|
|
N
|
|
|
0.510
|
N0
|
590 (55%)
|
237 (52%)
|
|
N1
|
272 (25%)
|
122 (27%)
|
|
N2
|
217 (20%)
|
101 (22%)
|
|
M
|
|
|
0.702
|
M0
|
939 (87%)
|
397 (86%)
|
|
M1
|
140 (13%)
|
63 (14%)
|
|
LNR
|
|
|
0.640
|
<0.36
|
968 (90%)
|
409 (89%)
|
|
≥0.36
|
111 (10%)
|
51 (11%)
|
|
Grade
|
|
|
0.968
|
G1
|
97 (9.0%)
|
42 (9.1%)
|
|
G2
|
723 (67%)
|
313 (68%)
|
|
G3
|
206 (19%)
|
83 (18%)
|
|
G4
|
53 (4.9%)
|
22 (4.8%)
|
|
PIN
|
|
|
0.472
|
Yes
|
109 (10%)
|
41 (8.9%)
|
|
No
|
970 (90%)
|
419 (91.1%)
|
|
CEA
|
|
|
0.923
|
Negative
|
553 (51%)
|
237 (52%)
|
|
Positive
|
526 (49%)
|
223 (48%)
|
|
Size
|
|
|
0.169
|
<6cm
|
564 (52%)
|
258 (56%)
|
|
≥6cm
|
515 (48%)
|
202 (44%)
|
|
Chemotherapy
|
|
|
0.353
|
Yes
|
430 (40%)
|
195 (42%)
|
|
No
|
649 (60%)
|
265 (58%)
|
|
Site
|
|
|
0.989
|
Left
|
249 (23%)
|
106 (23%)
|
|
Right
|
830 (77%)
|
354 (77%)
|
|
Table 2 丨Clinicopathologic features of colon MAC in the external validation set.
Characteristic
|
external validation set, N = 116
|
Age
|
|
<80
|
107 (92.2%)
|
≥80
|
9 (7.8%)
|
T
|
|
T1
|
2 (1.7%)
|
T2
|
4 (3.4%)
|
T3
|
75 (64.7%)
|
T4
|
35 (30.2%)
|
M
|
|
M0
|
84 (72.4%)
|
M1
|
32 (27.6%)
|
LNR
|
|
<0.36
|
107 (92.2%)
|
≥0.36
|
9 (7.8%)
|
Grade
|
|
G1
|
14 (12.1%)
|
G2
|
39 (33.6%)
|
G3
G4
|
63 (54.3%)
0 (0.0%)
|
A total of 1539 patients from the SEER database and 116 patients from a single center in China were eventually enrolled in this study according to the criteria of inclusion and exclusion. Patients from SEER were randomly divided into a training set (n=1079) and an internal validation set (n=460) at a ratio of 7 to 3. As shown in Table 1, there was no significant difference between the training set and the internal validation set through the Chi-square test. In the training set, 72% were younger than 80 years old, and 28% were older than 80 years old. Males accounted for 49% and females 51%. Caucasians have the largest share, accounting for 81%. The right colon which is about 3 times larger than the left colon accounted for 77%. The proportion of CEA negative and positive was almost the same, 51% and 49% respectively. T stage was mainly T3, accounting for 57%. N0, N1 and N2 accounted for 55%, 25%, and 20% respectively. The M stage was mainly M0, accounting for 87%. LNR < 0.36 dominated, accounting for 90%. G1, G2, G3, and G4 accounted for 9%, 67%, 19%, and 4.9% respectively. The patients with PNI accounted for 10.0%. <6cm and ≥6cm accounted for 52% and 48% respectively. 40% of the patients had experienced chemotherapy. The clinicopathological features of the external validation set are shown in Table 2.
Determining Prognostic Factors of MAC Patients in the Training Set
To determine OS-related variables, age, sex, race, tumor site, CEA, T, N, LNR, M, grade, PNI, tumor size, and chemotherapy were included in the univariate Cox analysis. The results are shown in Table 3, which showed that age, tumor site, CEA, T, N, LNR, M, grade, PNI, and tumor size was identified as OS-related variables. Subsequently, variables with statistical differences in univariate COX regression analysis were included in multivariate COX regression analysis, and the result of multivariate COX regression analysis indicated that age, T, N, LNR, M, and grade were independently associated with OS of MAC patients.
Development and Validation of the Prognostic Nomogram
To predict the OS of MCA, a nomogram was established based on all independent prognostic factors from the training set, which is shown in Figure 3. To test the performance of the model, a receiver operating curve is plotted and showed that the AUC values in 1-, 3-, and 5-years were 0.786, 0.795, and 0.788 respectively, which suggested the favorable discrimination of the nomogram. Then, the AUC values in 1-, 3- and 5-years were 0.730, 0.748, and 0.744 in the internal validation set and 0.859, 0.782, and 0.819 in the external validation set respectively. The above ROC curve is shown in Figure 4. Besides, the calibration curves indicated that the nomogram has a strong calibration, which is shown in Figure 5. Meanwhile, DCA was performed, and the results indicated that the nomogram has high clinical application value and could serve as an effective tool for clinical practice, which is shown in Figure 6.
Risk Stratification for MAC Patients
MAC patients can be divided into high-, and low-risk groups via the prognostic nomogram established in this study. As shown in Figure 7, the results of the Kaplan-Meier survival analysis with log-rank test suggested that significantly different survival patterns among patients existed in the two risk groups. Besides, patients both in the internal and external validation sets were also divided into two risk groups. The prognosis of patients in the low-risk group was better than that in the high-risk group. The above results suggested that the model can divide MAC patients into two groups with different prognoses to provide clinicians with a reference for decision-making.
Comparison of Predictive Accuracy
As shown in Figure 8, the AUC values of TNM in the training set and the validation sets were higher than 0.5. By comparing the predictive power between the nomogram and TNM, the AUC value of the nomogram constructed in this study was higher than TNM in 1-, 3- and 5-years both in the training set and the internal validation sets, suggesting the excellent performance of the nomogram.