Perioperative chemotherapy improves survival of patients with locally advanced diffuse gastric cancer

Table 1 Baseline clinicopathologic characteristics of patients with diffuse gastric adenocarcinoma with or without perioperative chemotherapy before and after inverse probability of treatment weighting, n (%)

Characteristic	Before IPTW			After IPTW
	Surgery alone (n = 1236)	Perioperative chemotherapy (n = 1448)	P value	Surgery alone (n = 2660.3)	Perioperative chemotherapy (n = 2721.4)	P value
Age			< 0.001			0.883
≤ 45	59 (4.8)	241 (16.6)		316.8 (11.9)	301.3 (11.1)
45-70	449 (36.3)	855 (59.0)		1268.4 (47.7)	1312.5 (48.2)
≥ 70	728 (58.9)	352 (24.3)		1075.0 (40.4)	1107.6 (40.7)
Sex			0.111			0.191
Male	634 (51.3)	697 (48.1)		1385.5 (52.1)	1328.0 (48.8)
Female	602 (48.7)	751 (51.9)		1274.8 (47.9)	1393.4 (51.2)
Race			0.041			0.456
White	828 (67.0)	915 (63.2)		1742.1 (65.5)	1678.2 (61.7)
Black	140 (11.3)	152 (10.5)		321.1 (12.1)	335.6 (12.3)
Asian	252 (20.4)	353 (24.4)		552.6 (20.8)	654.7 (24.1)
Other	16 (1.3)	28 (1.9)		44.4 (1.7)	52.9 (1.9)
Diagnosis period			< 0.001			0.799
2004-2010	693 (56.1)	275 (19.0)		980.3 (36.8)	1019.9 (37.5)
2010-2020	543 (43.9)	1173 (81.0)		1680.0 (63.2)	1701.6 (62.5)
Tumor location			0.001			0.994
Upper one-third	131 (10.6)	188 (13.0)		313.3 (11.8)	315.8 (11.6)
Middle one-third	351 (28.4)	481 (33.2)		809.9 (30.4)	838.2 (30.8)
Lower one-third	447 (36.2)	428 (29.6)		889.2 (33.4)	916.4 (33.7)
Over lapping	156 (12.6)	196 (13.5)		351.3 (13.2)	366.4 (13.5)
Unknown	151 (12.2)	155 (10.7)		296.5 (11.1)	284.6 (10.5)
Histology type			0.117			0.069
Diffuse	349 (28.2)	410 (28.3)		835.0 (31.4)	716.8 (26.3)
Signet-ring cell carcinoma	852 (68.9)	1014 (70.0)		1767.7 (66.4)	1950.4 (71.7)
Linitis plastica	35 (2.8)	24 (1.7)		57.6 (2.2)	54.3 (2.0)
Grade			0.307			0.576
Well/Moderately differentiated	34 (2.8)	30 (2.1)		61.2 (2.3)	53.6 (2.0)
Poorly/undifferentiated	1202 (97.2)	1418 (97.9)		2599.1 (97.7)	2667.8 (98.0)
T stage			< 0.001			0.921
1	76 (6.1)	86 (5.9)		184.4 (6.9)	172.7 (6.3)
2	73 (5.9)	160 (11.0)		206.9 (7.8)	231.2 (8.5)
3	562 (45.5)	678 (46.8)		1208.2 (45.4)	1220.7 (44.9)
4	525 (42.5)	524 (36.2)		1060.7 (39.9)	1096.8 (40.3)
N stage			0.084			0.821
0	333 (26.9)	388 (26.8)		741.1 (27.9)	706.2 (26.0)
1	261 (21.1)	362 (25.0)		558.6 (21.0)	566.3 (20.8)
2	280 (22.7)	292 (20.2)		575.2 (21.6)	619.6 (22.8)
3	362 (29.3)	406 (28.0)		785.4 (29.5)	829.4 (30.5)
D2 surgery			< 0.001			0.969
No	914 (73.9)	667 (46.2)		1573.7 (59.2)	1607.3 (59.1)
Yes	322 (26.1)	781 (53.8)		1086.5 (40.8)	1114.1 (40.9)
OS (95%CI)
1-year	51.6 (48.9, 54.5)	84.6 (82.6, 86.5)		57.2 (53.9, 60.8)	79.2 (76.0, 82.5)
3-year	27.0 (24.5, 29.6)	52.3 (49.5, 55.2)		33.9 (30.4, 37.9)	47.3 (43.8, 51.1)
5-year	19.6 (17.4, 22.1)	40.0 (37.1, 43.0)		26.4 (22.9, 30.4)	35.0 (31.5, 38.9)
Median OS (95%CI), month	13.0 (12.0, 15.0)	40.0 (36.0, 44.0)		17.0 (15.0, 20.0)	33.0 (30.0, 38.0)
CSS (95%CI)
1-year	57.9 (55.1, 60.9)	86.3 (84.4, 88.1)		62.5 (59.1, 66.1)	81.3 (78.1, 84.5)
3-year	34.9 (32.0, 38.0)	56.3 (53.5, 59.3)		41.3 (37.4, 45.5)	51.5 (47.8, 55.4)
5-year	28.0 (25.2, 31.0)	45.3 (42.3, 48.5)		34.3 (30.3, 38.7)	41.2 (37.5, 45.3)
Median CSS (95%CI), month	18.0 (16.0, 21.0)	47.0 (42.0, 54.0)		24.0 (20.0, 30.0)	39.0 (33.0, 45.0)

OS: Overall survival; CSS: Cancer-specific survival; IPTW: Inverse probability of treatment weighting; CI: Confidence interval.