Table 2. Univariable and multivariable Cox proportional hazard analyses of postoperative recurrence-free survival in the development set.

Parameter		Univariable Cox proportional hazard analysis			Multivariable Cox proportional hazard analysis
		Regression coefficient	HR (95% CI)	P	Regression coefficient	HR (95% CI)	P
Age (1-year increment)		0.00	1.00 (0.99–1.02)	0.80
Sex, male		0.17	1.19 (0.92–1.53)	0.19
Body mass index (1 kg/m2 increment)		-0.02	0.98 (0.94–1.02)	0.29
Tumor size (1 cm increment)		0.31	1.37 (1.22–1.52)	< 0.001	0.25	1.29 (1.14–1.45)	< 0.001
Dominant tumor location				0.30
	Head	0.00	1 (reference)
	Body	-0.10	0.90 (0.65–1.26)	0.55
	Tail	0.20	1.22 (0.89–1.67)	0.21
Adjacent organ invasion		0.34	1.40 (1.08–1.83)	0.01
Tumor maximum standardized uptake value ≥ 5.2		0.44	1.55 (1.21–1.99)	0.001	0.25	1.29 (0.99–1.67)	0.06
Suspicious regional lymph node		0.54	1.71 (1.29–2.26)	< 0.001	0.36	1.43 (1.07–1.91)	0.02
Possible distant metastasis on 18F-FDG PET/CT		0.95	2.59 (1.22–5.50)	0.01	0.84	2.32 (1.08–4.99)	0.03
CA 19-9 (100 U/mL increment)		0.03	1.03 (1.02–1.05)	< 0.001	0.02	1.02 (1.01–1.04)	0.002
Bilirubin (1 mg/dL increment)		0.04	1.04 (0.96–1.12)	0.35
Albumin (1 g/dL increment)		-0.06	0.94 (0.68–1.31)	0.72
Lymphocyte (1 × 109/L increment)		-0.011	0.89 (0.74–1.08)	0.24
Platelet (1 × 109/L increment)		0.00	1.00 (1.00–1.00)	0.80
Alkaline phosphatase (1 IU/L increment)		0.00	1.00 (1.00–1.00)	0.41
C-reactive protein (1 mg/dL increment)		0.01	1.01 (0.91–1.11)	0.90

HR = hazard ratio, CI = confidence interval, ¹⁸F-FDG = fluorine-18-fluorodeoxyglucose, CA 19-9 = carbohydrate antigen 19-9