Table 1. Relationship between clinicopathologic features and baseline serum CA125 Levels.

Features	Training Cohort (n = 259)			Validation Cohort (n = 273)
	Baseline Serum CA125 Levels		P	Baseline Serum CA125 Levels		P
	Negative (n = 142)	Positive (n = 117)		Negative (n = 108)	Positive (n = 165)
Age (years)			0.073			0.217
< 62	63	65		58	76
≥ 62	79	52		50	89
Gender			0.536			0.324
Male	82	72		68	94
Female	60	45		40	71
Tumor location			0.777			0.445
Head	85	68		83	120
Body/tail	57	49		25	45
Tumor size (cm)			0.001			0.026
≤ 4.0	85	46		62	72
> 4.0	57	71		46	93
Lymph node metastasis			< 0.001			0.001
Yes	52	81		48	108
No	90	36		60	57
Differentiation			0.093			0.197
Well/Moderate	44	48		75	102
Poor	98	69		33	63
Neural invasion			0.388			0.268
Yes	117	101		69	116
No	25	16		39	49
Vascular invasion			0.237			0.822
Yes	31	33		32	51
No	111	84		76	114
TNM stage			< 0.001			0.001
I	33	15		32	22
IIA	57	21		28	35
IIB	52	81		48	108
Chemotherapy			0.361			0.912
Any	118	92		74	112
No	24	25		34	53
Chemoradiotherapy			0.274			0.390
Any	40	26		13	26
No	102	91		95	139
CA19-9 non-decrease			0.029			< 0.001
Yes	25	34		6	61
No	117	83		102	104
Early distant metastasis			< 0.001			< 0.001
Yes	18	47		6	55
No	124	70		102	110

Note: 18.4 U/mL was identified by ROC curve analysis as the cut-off value for positive/negative baseline serum CA125. Early distant metastasis is defined as the recurrence in distant organs within 6 months after surgery