Survival benefit of younger gastric cancer patients in China and the United States: A comparative study

Table 1 Demographic and clinicopathological characteristics of younger gastric cancer patients in China and the United States from 2000 to 2018

	China (n = 1159), n (%)		United States (n = 4939), n (%)		P value
Period of diagnosis					< 0.0001
1 (2000-2003)	194	16.7	972	19.7
2 (2004-2008)	237	20.5	1248	25.3
3 (2009-2013)	396	34.3	1280	25.9
4 (2014-2018)	332	28.6	1439	29.1
Race					< 0.0001
Chinese	1159	100.0	126	2.6
White			3405	69.9
Black			703	14.4
Others			640	13.1
Gender					0.135
Male	581	50.1	2599	52.6
Female	578	49.9	2340	47.4
Age (year), mean ± SD					0.005
	34		32.91
	5		5.38
Primary tumor location					< 0.0001
Proximal	176	16.3	1030	33.3
Distal	903	83.7	2067	66.7
Differentiation					< 0.0001
Well	9	1.2	211	7.5
Moderate	124	16.3	394	14.0
Poor/Undifferentiated	626	82.5	2214	78.5
Linitis plastica					0.070
Yes	29	2.6	57	1.7
No	1101	97.4	3279	98.3
Signet ring cell carcinoma					< 0.0001
Yes	426	52.9	1429	28.9
No	380	47.1	3510	71.1
Pathologic T-stage (AJCC 8th)					< 0.0001
T1	197	22.2	498	24.3
T2	97	10.9	266	13.0
T3	143	16.1	509	24.9
T4	452	50.8	773	37.8
Pathologic N-stage (AJCC 8th)					< 0.0001
N0	412	41.8	1137	49.9
N1	119	12.1	724	31.7
N2	162	16.4	232	10.2
N3	292	29.6	188	8.2
Pathologic M-stage					< 0.0001
M0	869	79.4	1268	45.9
M1	225	20.6	1492	54.1
pTNM stage (AJCC TNM 8th)					< 0.0001
I	222	21.2	649	20.3
II	169	16.1	377	11.7
III	433	41.3	498	15.5
IV	225	21.4	1687	52.5
Surgery					< 0.0001
Yes	869	75.1	2047	41.4
No	288	24.9	2892	58.6
Chemotherapy					< 0.0001
Yes	428	36.9	2991	60.6
No	731	63.1	1948	39.4
Lymphadenectomy					< 0.0001
Yes	780	67.4	941	19.1
No	377	32.6	3398	80.9
Lymphadenectomy with at least 15 lymph nodes					< 0.0001
Yes	606	52.4	524	10.6
No	551	47.6	4415	89.4
Number nodes examined (n), mean ± SD					< 0.0001
	25		18.9
	13		15.0
Number positive nodes (n), mean ± SD					< 0.0001
	6		7.4
	8		7.4

AJCC: American Joint Committee on Cancer; pTNM: Pathological Tumor-Node-Metastasis; SD: Standard deviation.

Table 2 Overall survival rates by background characteristics from 2000 to 2018

Characteristics	China			United States
	1-yr, % (95%CI)	3-yr, % (95%CI)	5-yr, % (95%CI)	1-yr, % (95%CI)	3-yr, % (95%CI)	5-yr, % (95%CI)
Total
Period of diagnosis
1 (2000-2003)	75.0 (63.2-89.0)	54.5 (41.7-71.4)	47.7 (35.0-65.0)	58.4 (55.3-61.7)	40.7 (37.7-44.0)	36.2 (33.2-39.4)
2 (2004-2008)	80.1 (74.5-86.1)	59.7 (52.9-67.3)	54.1 (47.4-61.9)	58.1 (55.4-61.0)	42.3 (39.6-45.2)	38.4 (35.7-41.3)
3 (2009-2013)	76.7 (72.3-81.3)	57.1 (52.1-62.6)	51.6 (46.6-57.2)	60.8 (58.1-63.6)	44.0 (41.2-46.9)	39.7 (37.0-42.6)
4 (2014-2018)	88.6 (85.1-92.3)	66.5 (60.8-72.7)		61.6(58.9-64.4)	43.0 (39.9-46.4)
Race
Chinese	81.4 (78.9-84.1)	60.9 (57.6-64.3)	52.3 (48.8-56.0)	66.0 (58.1-75.1)	52.9 (44.4-62.9)	42.9 (34.4-53.5)
White				59.7 (58.1-61.5)	41.7 (40.0-43.6)	37.8 (36.0-39.6)
Black				58.0 (54.3-61.8)	42.7 (39.0-46.7)	38.2 (34.6-42.3)
Others				59.4 (55.6-63.5)	43.3 (39.4-47.6)	37.2 (33.3-41.6)
Gender
Male	82.2 (78.7-85.8)	61.5 (57.1-66.2)	53.6 (49.0-58.7)	57.0 (55.0-59.0)	39.6 (37.6-41.7)	34.8 (32.8-36.9)
Female	80.6 (76.9-84.5)	60.2 (55.5-65.3)	50.7 (45.7-56.2)	63.0 (61.0-65.1)	46.2 (44.1-48.4)	42.2 (40.1-44.4)
Primary tumor location
Proximal	76.7 (69.8-84.2)	47.7 (39.8-57.2)	42.7 (34.7-52.4)	59.0 (56.0-62.2)	35.8 (32.8-39.1)	30.5 (27.5-33.7)
Distal	84.5 (81.8-87.3)	66.3 (62.8-70.1)	57.4 (53.5-61.5)	64.6 (62.5-66.7)	48.0 (45.8-50.4)	42.9 (40.6-45.3)
Differentiation
Well	100.0 (100.0-100.0)	100.0 (100.0-100.0)	85.7 (63.3-100.0)	92.5 (88.9-96.2)	83.3 (78.0-89.0)	78.8 (72.6-85.6)
Moderate	90.4 (84.7-96.6)	76.1 (67.6-85.6)	66.3 (56.4-78.0)	72.3 (67.9-76.9)	50.1 (45.2-55.5)	44.6 (39.6-50.1)
Poor/Undifferentiated	87.7 (84.8-90.7)	69.6 (65.4-74.0)	61.6 (57.0-66.5)	48.3 (46.3-50.5)	25.7 (23.9-27.6)	19.9 (18.2-21.8)
Linitis plastica
Yes	57.1 (39.5-82.8)	14.3 (5.0-40.7)	4.8 (0.7-32.2)	49.5 (37.8-65.0)	14.8 (7.6-29.0)	12.3 (5.8-26.4)
No	83.9 (81.4-86.6)	68.7 (65.4-72.2)	63.8 (60.2-67.5)	60.0 (58.6-61.4)	43.1 (41.6-44.6)	38.6 (37.1-40.1)
Signet ring cell carcinoma
Yes	91.0 (87.9-94.2)	80.3 (75.8-85.0)	76.9 (72.1-82.1)	49.5 (37.8-65.0)	14.8 (7.6-29.0)	12.3 (5.8-26.4)
No	90.2 (86.7-93.8)	75.1 (70.0-80.6)	70.8 (65.2-76.8)	60.0 (58.6-61.4)	43.1 (41.6-44.6)	38.6 (37.1-40.1)
pTNM stage (AJCC TNM 8th)
I	100.0 (100.0-100.0)	99.4 (98.4-100.0)	99.4 (98.4-100.0)	91.5 (89.3-93.8)	86.4 (83.6-89.2)	83.4 (80.2-86.6)
II	97.1 (94.3-99.9)	83.6 (77.5-90.3)	69.8 (61.9-78.7)	84.2 (80.4-88.2)	68.4 (63.4-73.8)	61.0 (55.5-67.0)
III	83.5 (79.4-87.9)	54.9 (49.3-61.0)	42.6 (37.0-49.2)	74.8 (70.9-78.8)	41.0 (36.5-46.1)	29.6 (25.3-34.7)
IV	51.2 (43.8-59.7)	17.4 (12.3-24.8)	9.9 (6.0-16.3)	29.7 (27.5-32.1)	10.4 (8.8-12.1)	7.1 (5.7-8.7)
Surgery
Yes	89.6 (87.3-92.0)	72.4 (69.0-76.0)	63.4 (59.5-67.5)	82.6 (80.9-84.3)	61.2 (59.0-63.5)	53.6 (51.3-56.1)
No	58.4 (51.8-65.9)	33.4 (26.9-41.5)	28.7 (22.2-37.0)	43.2 (41.3-45.1)	29.1 (27.4-31.0)	27.0 (25.3-28.9)
Chemotherapy
Yes	89.1 (85.8-92.6)	67.0 (61.9-72.6)	52.7 (47.1-59.1)	55.9 (54.1-57.8)	32.7 (31.0-34.6)	27.4 (25.7-29.2)
No	76.8 (73.3-80.4)	57.2 (53.1-61.6)	51.9 (47.7-56.5)	66.4 (64.2-68.6)	59.2 (56.9-61.6)	56.2 (53.9-58.7)
Lymphadenectomy
Yes	90.8 (88.4-93.2)	77.7 (74.3-81.3)	73.7 (69.9-77.6)	70.9 (67.9-73.9)	39.4 (36.2-42.8)	29.2 (26.1-32.6)
No	64.0 (58.3-70.3)	41.4 (35.4-48.5)	35.1 (29.0-42.5)	57.2 (55.6-58.8)	43.7 (42.1-45.4)	40.7 (39.1-42.4)
Lymphadenectomy with at least 15 lymph nodes
Yes	91.8 (89.3-94.3)	79.9 (76.2-83.3)	76.2 (72.2-80.6)	77.3 (73.7-81.1)	43.4 (39.4-48.6)	32.4 (28.1-37.2)
No	86.5 (80.4-93.1)	69.0 (60.9-78.3)	64.1 (55.6-73.8)	63.0 (58.4-67.9)	34.0 (29.6-39.1)	25.3 (21.2-30.2)

AJCC: American Joint Committee on Cancer; CI: Confidence interval pTNM: Pathological Tumor-Node-Metastasis.

Table 3 Univariate Cox regression analysis of younger gastric cancer patients in China and the United States

Characteristics		Total		P value	China		P value	United States		P value	China vs United States		P value
		HR	95%CI		HR	95%CI		HR	95%CI		HR	95%CI
Region	China	1
	United States	2.06	1.84-2.31	< 0.0001
Race	Chinese	1						1			1.24	1.00-1.54	0.11
	White	2.08	1.85-2.33	< 0.0001				1.22	0.95-1.56	0.12
	Black	2.14	1.85-2.47	< 0.0001				1.26	0.97-1.63	0.08
	Others	2.07	1.79-2.38	< 0.0001				1.26	0.97-1.64	0.08
Period of diagnosis	Period 1 (2000-2003)	1			1			1			1.12	0.83-1.49	0.55
	Period 2 (2004-2008)	0.90	0.81-0.99	0.009	0.67	0.45-1.00	0.05	0.95	0.85-1.05	0.30	1.52	1.27-1.80	< 0.0001
	Period 3 (2009-2013)	0.87	0.78-0.96	0.008	0.84	0.57-1.22	0.35	0.91	0.82-1.01	0.09	1.36	1.19-1.55	< 0.0001
	Period 4 (2014-2018)	0.84	0.76-0.94	0.008	0.74	0.49-1.10	0.14	0.91	0.82-1.02	0.10	2.03	1.72-2.41	< 0.0001
Gender	Male	1			1			1			1.70	1.51-1.91	< 0.0001
	Female	0.85	0.80-0.91	< 0.0001	1.05	0.87-1.26	0.64	0.82	0.76-0.88	< 0.0001	1.52	1.27-1.80	< 0.0001
Primary tumor location	Proximal	1			1			1			1.30	1.08-1.57	0.02
	Distal	0.68	0.62-0.75	< 0.0001	0.59	0.47-0.75	< 0.0001	0.77	0.70-0.85	< 0.0001	1.56	1.40-1.74	< 0.0001
Differentiation	Well	1			1			1			1.10	0.33-3.62	0.90
	Moderate	2.82	2.05-3.88	< 0.0001	1.62	0.39-6.76	0.51	3.17	2.28-4.42	< 0.0001	2.14	1.56-2.94	< 0.0001
	Poor/Undifferentiated	5.27	3.91-7.11	< 0.0001	2.19	0.54-8.83	0.27	6.15	4.53-8.35	< 0.0001	3.20	2.83-3.62	< 0.0001
Linitis plastica	Yes	1.95	1.58-2.40	< 0.0001	3.69	2.41-5.65	< 0.0001	1.89	1.41-2.52	< 0.0001	1.03	0.66-1.60	0.91
	No	1			1			1			2.25	2.03-2.50	< 0.0001
Signet ring cell carcinoma	Yes	1.61	1.52-1.72	< 0.0001	0.80	0.61-1.05	0.18	2.01	1.86-2.17	< 0.0001	6.53	5.33-7.99	< 0.0001
	No	1			1			1			2.45	2.02-2.96	< 0.0001
pTNM stage (AJCC TNM 8th)	1			1	1			1			9.88	4.28-22.83	< 0.0001
	2.85	2.25-3.60	< 0.0001	2.85	19.50	7.04-54.05	< 0.0001	2.27	1.76-2.93	< 0.0001	1.27	0.96-1.67	0.16
	6.18	5.04-7.58	< 0.0001	6.18	46.77	17.36-125.96	< 0.0001	4.88	3.93-6.07	< 0.0001	1.31	1.13-1.53	0.003
	19.52	16.09-23.68	< 0.0001	19.52	137.73	50.88-372.83	< 0.0001	14.25	11.69-17.36	< 0.0001	1.46	1.26-1.68	< 0.0001
Surgery	Yes	0.36	0.34-0.38	< 0.0001	0.23	0.19-0.28	< 0.0001	0.41	0.37-0.44	< 0.0001	1.29	1.15-1.45	0.0002
	No	1			1			1			1.25	1.08-1.25	0.01
Chemotherapy	Yes	1.71	1.59-1.84	< 0.0001	0.93	0.77-1.13	0.45	1.80	1.66-1.95	< 0.0001	2.10	1.84-2.40	< 0.0001
	No	1			1			1			0.97	0.87-1.09	0.69
Lymphadenectomy with at least 15 lymph nodes	Yes	0.56	0.49-0.63	< 0.0001	0.64	0.47-0.87	< 0.0001	0.73	0.63-0.86	0.0001	2.49	2.12-2.91	< 0.0001
	No	1			1			1			3.86	3.21-4.65	< 0.0001

AJCC: American Joint Committee on Cancer; CI: Confidence interval; HR: Hazard ratio; pTNM: Pathological Tumor-Node-Metastasis.

Table 4 Multivariate Cox regression analysis of younger gastric cancer patients in China and the United States

Characteristics		Total1		P value	China2		P value	United States3		P value
		HR	95%CI		HR	95%CI		HR	95%CI
Region	China	1
	United States	2.42	1.35-4.33	0.01
Race	Chinese	1						1
	White	0.80	0.45-1.41	0.52				1.21	0.94-1.55	0.13
	Black	0.84	0.46-1.53	0.63				1.48	1.14-1.92	0.003
	Others	0.76	0.42-1.38	0.45				1.19	0.91-1.55	0.20
Period of diagnosis	Period 1 (2000-2003)	1			1			1
	Period 2 (2004-2008)	0.62	0.27-0.78	0.02	0.51	0.29-0.89	0.047	0.55	0.47-0.64	< 0.0001
	Period 3 (2009-2013)	0.54	0.25-0.73	0.01	0.39	0.22-0.67	0.004	0.50	0.43-0.59	< 0.0001
	Period 4 (2014-2018)	0.48	0.16-0.49	0.0002	0.07	0.03-0.14	< 0.0001	0.47	0.40-0.56	< 0.0001
Gender	Male	1						1
	Female	0.92	0.80-1.07	0.35				0.85	0.79-0.92	< 0.0001
Primary tumor location	Proximal	1			1			1
	Distal	0.92	0.75-1.12	0.47	0.88	0.60-1.29	0.58	0.88	0.80-0.98	0.02
Differentiation	Well	1						1
	Moderate	2.89	0.88-9.48	0.14				1.90	1.36-2.65	0.0002
	Poor/Undifferentiated	4.77	1.47-15.44	0.03				2.97	2.16-4.07	< 0.0001
Linitis plastica	Yes	1.73	1.12-2.68	0.04	6.70	2.72-16.50	0.0005	1.63	1.21-2.19	0.001
	No/unknown	1			1			1
Signet ring cell carcinoma	Yes	1.07	0.92-1.24	0.47				1.48	1.36-1.61	< 0.0001
	No/unknown	1						1
pTNM stage (AJCC TNM 8th)	I	1			1			1
	II	10.96	5.05-23.75	< 0.0001	18.69	5.55-62.96	< 0.0001	2.35	1.81-3.04	< 0.0001
	III	27.32	12.87-58.00	< 0.0001	58.95	18.18-191.13	< 0.0001	4.51	3.57-5.69	< 0.0001
	IV	57.20	26.58-123.10	< 0.0001	158.6	43.85-573.93	< 0.0001	8.26	6.72-10.16	< 0.0001
Surgery	Yes	0.50	0.36-0.70	0.0005	0.46	0.20-1.03	0.11	0.42	0.37-0.46	< 0.0001
	No	1			1			1
Chemotherapy	Yes	0.69	0.58-0.84	0.001				0.82	0.75-0.90	< 0.0001
	No	1						1
Lymphadenectomy with at least 15 lymph nodes	Yes	0.74	0.63-0.86	0.001	0.88	0.64-1.20	0.49	1.04	0.90-1.20	0.64
	No	1			1			1

¹Adjusted factors for total patients: region, race, period, sex, primary tumor location, differentiation, linitis plastica, signet ring cell carcinoma, pathological Tumor-Node-Metastasis (pTNM) stage, surgery, chemotherapy, lymphadenectomy with at least 15 lymph nodes.

²Adjusted factors for patients from China cohort: period, primary tumor location, linitis plastica, pTNM stage, surgery, lymphadenectomy with at least 15 lymph nodes.

³Adjusted factors for patients from the United States cohort: race, period, sex, primary tumor location, differentiation, linitis plastica, signet ring cell carcinoma, pTNM stage, surgery, chemotherapy, lymphadenectomy with at least 15 lymph nodes.

AJCC: American Joint Committee on Cancer; CI: Confidence interval; HR: Hazard ratio.