Adjuvant chemotherapy with S-1 plus oxaliplatin improves survival of patients with gastric cancer after D2 gastrectomy: A multicenter propensity score-matched study

Table 1 Clinicopathologic features of the study population undergoing surgery alone and receiving adjuvant S-1 plus oxaliplatin chemotherapy before and after propensity score-matching n (%)

Variable	Before PSM (n = 807)			After PSM (n = 351)
	Surgery alone(n = 683)	Adjuvant SOX(n = 124)	P value	Surgery alone(n = 234)	Adjuvant SOX(n = 117)	P value
Age at diagnosis (yr)			0.099			0.443
< 35	9 (1.32)	3 (2.42)		3 (1.28)	0 (0.00)
35-60	303 (44.36)	66 (53.23)		118 (50.43)	62 (52.99)
> 60	371 (54.32)	55 (44.35)		113 (48.29)	55 (47.01)
Gender			0.83			1
Female	177 (25.92)	31 (25.00)		60 (25.64)	30 (25.64)
Male	506 (74.08)	93 (75.00)		174 (74.36)	87 (74.36)
Tumor location			0.063			0.424
None-Cardia cancer	425 (62.23)	88 (70.97)		152 (64.96)	81 (69.23)
Cardia cancer	258 (37.77)	36 (29.03)		82 (35.04)	36 (30.77)
Tumor grade			0.006			0.725
Moderate to well	50 (7.32)	4 (3.23)		14 (5.98)	4 (3.42)
Moderate	171 (25.04)	21 (16.94)		36 (15.38)	21 (17.95)
Poor to moderate	427 (62.52)	97 (78.23)		180 (76.92)	90 (76.92)
Early cancer or not reported	35 (5.12)	2 (1.61)		4 (1.71)	2 (1.71)
Pathological stage			< 0.001			0.604
IB1	302 (44.22)	8 (6.45)		20 (8.55)	8 (6.84)
II	127 (18.59)	29 (23.39)		48 (20.51)	29 (24.79)
III	254 (37.19)	87 (70.16)		166 (70.94)	80 (68.38)
Lymphatic and venous invasion			< 0.001			0.574
No	573 (83.89)	86 (69.35)		155 (66.24)	81 (69.23)
Yes	110 (16.11)	38 (30.65)		79 (33.76)	36 (30.77)
Perineural invasion			0.437			0.754
No	606 (88.73)	107 (86.29)		197 (84.19)	100 (85.47)
Yes	77 (11.27)	17 (13.71)		37 (15.81)	17 (14.53)

¹Patients of stage IB (pT2N0M0) without high-risk features including poorly differentiated or higher grade cancer, lymphovascular invasion, neural invasion, or < 50 years of age were not included. SOX: S-1 plus oxaliplatin; PSM: Propensity score-matching.