Features of synchronous and metachronous dual primary gastric and colorectal cancer

Table 1 Comparison of the features of metachronous and synchronous cancers

Characteristics		Overall, n = 76	Metachronous, n = 30	Synchronous, n = 46	P value
Age (yr) (%)	≤ 65	35 (46.1)	15 (50.0)	20 (43.5)	0.747
	> 65	41 (53.9)	15 (50.0)	26 (56.5)
Sex (%)	Female	24 (31.6)	9 (30.0)	15 (32.6)	1.000
	Male	52 (68.4)	21 (70.0)	31 (67.4)
Location of gastric cancer (%)	Lower	40 (52.6)	17 (56.7)	23 (50.0)	0.850
	Middle	11 (14.5)	4 (13.3)	7 (15.2)
	Upper	25 (32.9)	9 (30.0)	16 (34.8)
Stage of gastric cancer (%)	0-II	51 (67.1)	21 (70.0)	30 (65.2)	0.854
	III-IV	25 (32.9)	9 (30.0)	16 (34.8)
Resection of gastric cancer (%)	No	22 (28.9)	7 (23.3)	15 (32.6)	0.540
	Yes	54 (71.1)	23 (76.7)	31 (67.4)
Location of colorectal cancer (%)	Left hemicolon	6 (7.9)	2 (6.7)	4 (8.7)	0.121
	Rectum	27 (35.5)	14 (46.7)	13 (28.3)
	Right hemicolon	24 (31.6)	5 (16.7)	19 (41.3)
	Sigmoid colon	19 (25.0)	9 (30.0)	10 (21.7)
Stage of colorectal cancer (%)	0-II	44 (57.9)	16 (53.3)	28 (60.9)	0.680
	III-IV	32 (42.1)	14 (46.7)	18 (39.1)
Resection of colorectal cancer (%)	No	14 (18.4)	1 (3.3)	13 (28.3)	0.0151
	Yes	62 (81.6)	29 (96.7)	33 (71.7)

¹P value is statistically significant (P < 0.05).

Table 2 Univariate and multivariate analysis for predictors of overall survival

Characteristics		Univariate		Multivariate
		HR (95%CI)	P value	HR (95%CI)	P value
Age	≤ 65	Reference
	> 65	1.8 (0.8-4.1)	0.162
Sex	Female	Reference
	Male	0.9 (0.4-2.0)	0.719
Location of gastric cancer	Lower	Reference
	Middle	1.9 (0.6-6.2)	0.262
	Upper	1.8 (0.7-4.1)	0.200
Stage of gastric cancer	0-II	Reference
	III-IV	6.7 (2.9-15.6)	< 0.001	10.0 (3.4-29.5)	< 0.0011
Resection of gastric cancer	No	Reference
	Yes	0.1 (0.1-0.3)	< 0.001	0.2 (0.1-0.6)	0.0021
Location of colorectal cancer	Right hemicolon	Reference
	Left hemicolon	1.1 (0.2-5.3)	0.909
	Sigmoid colon	1.1 (0.4-3.1)	0.882
	Rectum	0.9 (0.3-2.5)	0.863
Stage of colorectal cancer	0-II	Reference
	III-IV	1.1 (0.5-2.4)	0.831
Resection of colorectal cancer	No	Reference
	Yes	0.3 (0.1-0.6)	0.002	0.4 (0.1-1.5)	0.202
DPGCC	Metachronous	Reference
	Synchronous	3.0 (1.3-7.2)	0.013	6.8 (2.0-22.7)	0.0021

¹P value is statistically significant (P < 0.05).

95%CI: 95% confidence interval; DPGCC: Dual primary gastric and colorectal cancer; HR: Hazard ratio.