Table 4. Univariate and multivariate associations between patient characteristics and survival among patients who received adjuvant therapy (n=39).

Characteristic	Hazard ratio (95% CI)	P value
Univariate associations
Age: ≥65 vs. <65	1.7 (0.8-3.7)	0.154
Age: continuous	1.0 (1.0-1.1)	0.19
Gender: female vs. male	0.8 (0.3-1.7)	0.507
ECOG: ≥1 vs. 0	1.2 (0.5-2.7)	0.751
Histologic grade: poorly differentiated vs. other	1.1 (0.4-3.3)	0.827
Tumor diameter: maximum cm (continuous)	1.3 (1.1-1.7)	0.015*
Tumor diameter: >3 vs. ≤3 cm	2.2 (0.8-5.7)	0.123
5-FU based chemotherapy only: yes vs. no	2.2 (0.7-6.8)	0.152
Gemcitabine based chemotherapy only: yes vs. no	0.6 (0.3-1.5)	0.298
Both 5-FU and gemcitabine based chemotherapy: yes vs. no	1.4 (0.6-3.1)	0.382
Platinum agent received: no vs. yes	2.8 (1.2-6.6)	0.015*
Lymph node involvement at resection: yes vs. no	1.9 (0.7-5.5)	0.243
T stage: T2 vs. ≥T3	0.8 (0.3-2.0)	0.625
Positive margin at resection: yes vs. no	2.0 (0.9-4.5)	0.08
Lymphovascular invasion: yes vs. no	2.5 (1.0-6.3)	0.051
Perineural invasion: yes vs. no	2.3 (0.8-6.7)	0.13
Received chemoradiation: no vs. yes	2.0 (0.9-4.4)	0.079
Multivariate associations
Platinum agent received: no vs. yes	2.4 (1.0-5.8)	0.040*
Tumor diameter: maximum cm (continuous)	1.3 (1.0-1.6)	0.047*

*, P<0.05. For categorical variables, the second group is the reference group for the Cox proportional hazard analysis. CI, confidence interval; ECOG, Eastern Cooperative Oncology Group; 5-FU, 5-fluorouracil.