Does gastric stump cancer really differ from primary proximal gastric cancer? A multicentre, propensity score matching-used, retrospective cohort study

Table 1 Clinicopathologic characteristics of included patients before and after propensity score matching

Variables	Before PSM				After PSM
	GSC (n = 178)	PGC (n = 957)	χ2/Z	P value	GSC (n = 152)	PGC (n = 152)	χ2/Z	P value
Gender			0.222	0.638			0.017	0.895
Female	44	221			38	39
Male	134	736			114	113
Age (yr)			0.452	0.502			0.020	0.0889
> 55	127	706			120	119
≤ 55	51	251			32	33
Tumor size			2.300	0.129			2.608	0.106
> 3.5 cm	103	611			91	77
≤ 3.5 cm	75	346			61	75
ASA grade			2.590	0.108			0.058	0.809
I/II	112	540			99	101
III/IV	66	417			53	51
Hospital stay after surgery (d)	12.65 ± 5.13	12.77 ± 4.42	1.023	0.133	11.13 ± 4.71	11.45 ± 5.90	1.156	0.232
Blood transfusion			10.705	0.001			2.114	0.156
Yes	42	127			34	57
No	126	780			108	85
Vascular invasion			0.405	0.525			0.920	0.337
Positive	36	339			32	70
Negative	51	415			49	82
Missing	91	203			71	-
Nerve invasion			0.475	0.491			0.280	0.596
Positive	49	389			40	63
Negative	55	378			49	89
Missing	74	190			63	-
Differentiation degree			18.537	0.000			1.452	0.028
High/median	38	100			27	21
Low	128	824			115	131
Missing	12	33			10	-
Depth of infiltration			0.310	0.578			0.838	0.360
T1/T2	40	198			36	43
T3/T4	138	762			116	109
Number of lymph nodes			3.859	0.049			6.752	0.009
≥ 7	101	617			94	115
< 7	77	340			58	37
Positive lymph nodes			0.570	0.450			19.667	0.000
≥ 3	86	433			71	109
< 3	92	524			81	43
TNM stage			10.367	0.006			0.062	0.969
I	15	132			17	18
II	43	168			38	39
III	94	657			97	95

PSM: Propensity score matching; GSC: Gastric stump cancer; PGC: Proximal gastric cancer; TNM: Tumor-node-metastasis; ASA: American Society of Anaesthesiologists.

Table 2 Univariate analysis of cancer-specific survival in gastric stump cancer and proximal gastric cancer

Variables	GSC				PGC
	n = 152	HR	95%CI	P value	n = 152	HR	95%CI	P value
Gender		1.991	0.937-3.422	0.038a		1.991	0.937-3.422	0.038a
Female	38				38
Male	114				114
Age (yr)		1.117	0.681-1.833	0.900		1.111	0.690-1.804	0.893
> 55	120				119
≤ 55	32				33
Tumor size		1.012	0.622-1.646	0.961		1.405	0.598-1.837	0.902
> 3.5 cm	91				77
≤ 3.5 cm	61				75
ASA grade		1.338	0.792-2.260	0.276		1.257	0.777-2.900	0.331
I/II	99				101
III/IV	53				51
Hospital stay after surgery (d)	11.13 ± 4.71	0.635	0.308-1.307	0.218	12.45 ± 5.90	0.873	0.299-1.780	0.412
Blood transfusion		1.114	0.655-1.896	0.690		1.296	0.588-2.001	0.255
Yes	44				67
No	108				85
Vascular invasion		1.662	0.210-2.138	0.630		1.603	1.000-9.568	0.049a
Positive	32				70
Negative	49				82
Missing	71				-
Nerve invasion		1.710	0.971-3.012	0.063		4.660	0.981-22.134	0.053
Positive	40				63
Negative	49				89
Missing	63				-
Differentiation degree		2.714	1.603-4.596	0.000a		3.503	1.734-11.385	0.000a
High/median	27				21
Low	115				131
Missing	10				-
Depth of infiltration		3.614	2.290-4.289	0.080		2.332	0.074-4.498	0.041a
T1/T2	36				43
T3/T4	116				109
Number of lymph nodes		0.792	0.336-1.869	0.595		3.432	0.874-12.441	0.077
≥ 7	94				115
< 7	58				37
Positive lymph nodes		0.223	0.110-0.881	0.124		0.485	0.260-0.906	0.023a
≥ 3	71				109
< 3	81				43
TNM stage		5.727	2.579- 12.715	0.000a		5.446	2.555-11.992	0.000a
I	17				18
II	38				39
III	97				95

^aP < 0.05.

HR: Hazard ratio; CI: Confidence interval; GSC: Gastric stump cancer; PGC: Proximal gastric cancer; TNM: Tumor-node-metastasis; ASA: American Society of Anaesthesiologists.

Table 3 Multivariate analysis of factors affecting cancer-specific survival

	GSC			PGC
	HR	95%CI	P value	HR	95%CI	P value
Gender	1.552	0.129-3.428	0.058	1.847	0.135-2.990	0.043
Differentiation degree	1.430	1.055-1.938	0.021a	1.999	0.636-3.004	0.027a
Depth of infiltration				2.929	1.383-4.691	0.000a
Positive lymph nodes				2.452	1.085-3.942	0.012a
TNM stage	1.426	1.040-1.955	0.027a	2.771	1.448-4.662	0.000a
Vascular invasion				1.269	0.680-3.998	0.070

^aP < 0.05.

HR: Hazard ratio; CI: Confidence interval; GSC: Gastric stump cancer; PGC: Proximal gastric cancer.