Cystic duct cancer: Should it be deemed as a type of gallbladder cancer?

Table 3 Three models to differentiate between gallbladder cancer and extrahepatic cholangiocarcinoma, and categorize cystic duct cancer cases

	Fisher’s linear discriminant	Binary logistic	ANN
	Coefficient in structure matrix	P value	Normalized importance (%)
Variable
Sex	0.479b	< 0.001a	26.1
Age at diagnosis	-0.091	< 0.001a	44.1
Year of diagnosis	0.018	0.508	12.4
Martial status	0.164	0.088	7.1
Race	-0.011	0.426	22
Tumor size	-0.215	< 0.001a	71.8c
SEER historical stage	0.665b	< 0.001a	80.4c
Surgical procedure	-0.238b	< 0.001a	100.0c
Region	0.011	0.315	25.9
Histology	0.221	< 0.001a	26.6
Model performance
Accuracy (%)
Training sample (n = 5743)	70.1	72.7	82.2
Testing sample (n = 2430)	69.3	73.6	81.9
Whole (n = 8173)	69.9	73.0	82.1
AUROC (95% CI)	0.781 (0.771-0.791)	0.785 (0.775-0.795)	0.902 (0.895-0.908)
Categorization in CC cases
Categorized as GC (%)	8 (22.2)	9 (25.0)	8 (22.2)
Categorized as EC (%)	28 (77.8)	27 (75.0)	28 (77.8)

^aP < 0.05;

^bTop 3 variables with the highest absolute values in the Fisher’s linear discriminant model;

^cThe most important three variables in the artificial neuron network mode. ANN: Artificial neuron network; SEER: Surveillance, Epidemiology, and End Results; AUROC: Area under the receiver operating characteristic curve; CI: Confidence interval; CC: Cystic duct cancer; GC: Gallbladder cancer; EC: Extrahepatic cholangiocarcinoma.