Prognostic value of preoperative carcinoembryonic antigen/tumor size in rectal cancer

Table 1 Association of carcinoembryonic antigen/tumor size with baseline characteristics of rectal cancer patients n (%)

	Training cohort (n = 371)				Validation cohort (n = 185)
	Cases	Low	High	P-value	Cases	Low	High	P-value
Age	371	58 (21-89)	65 (32-86)	< 0.001a	185	61 (25-87)	57 (35-79)	0.149
Tumor size	371	4.3 (0.8-13)	4.3 (0.8-13.5)	0.773	185	4.5 (1-13)	4.3 (0.8-10)	0.472
Sex				0.419				0.199
Male	218	177 (58)	41 (64)		103	82 (53)	21 (68)
Female	153	130 (42)	23 (36)		82	72 (47)	10 (32)
TNM stage				0.008a				0.350
I	104	96 (31)	8 (12)		48	43 (28)	5 (16)
II	127	99 (32)	28 (44)		74	61 (40)	13 (42)
III	140	112 (36)	28 (44)		63	50 (32)	13 (42)
Differentiation				0.395				0.826
Poor	60	51 (17)	9 (14)		24	19 (12)	5 (16)
Moderate	209	176 (57)	33 (52)		102	85 (55)	17 (55)
High	102	80 (26)	22 (34)		59	50 (32)	9 (29)
Lymphovascular invasion				0.697				0.683
Negative	338	281 (92)	57 (89)		173	143 (93)	30 (97)
Positive	33	26 (8)	7 (11)		12	11 (7)	1 (3)
Perineural invasion				0.039a				0.073
Negative	340	286 (93)	54 (84)		172	146 (95)	26 (84)
Positive	31	21 (7)	10 (16)		13	8 (5)	5 (16)
CEA				< 0.001a				< 0.001a
0-5 ng/mL	263	262 (85)	1 (2)		127	126 (82)	1 (3)
> 5 ng/mL	108	45 (15)	63 (98)		58	28 (18)	30 (97)
CA 19-9				0.006a				0.027a
0-37 ng/mL	325	276 (90)	49 (77)		158	136 (88)	22 (71)
> 37 ng/mL	46	31 (10)	15 (23)		27	18 (12)	9 (29)

^aP < 0.05; CEA: Carcinoembryonic antigen; CA 19-9: Carbohydrate antigen 19-9.

Table 2 Univariate analysis of prognostic factors for overall survival

Variable	Training cohort (n = 371)			Validation cohort (n = 185)
	Hazard ratio	95%CI	P-value	Hazard ratio	95%CI	P-value
Age	1.02	1.00-1.04	0.024a	1.03	1.00-1.06	0.070
Tumor size	1.04	0.92-1.18	0.506	1.14	0.95-1.37	0.164
Sex (ref = male)	1.43	0.88-2.31	0.145	0.85	0.41-1.77	0.665
TNM1 (ref = stage I)	1.74	1.26-2.41	0.001a	1.93	1.15-3.22	0.012a
Differentiation1 (ref = poor)	0.58	0.40-0.84	0.004a	0.53	0.30-0.94	0.030a
Lymphovascular invasion (ref = negative)	1.88	0.96-3.68	0.066	3.11	1.19-8.13	0.021a
Perineural invasion (ref = negative)	1.03	0.41-2.56	0.954	1.29	0.31-5.46	0.729
CEA (ref = CEA < 5)	1.81	1.11-2.94	0.017a	2.72	1.33-5.59	0.006a
CA 19-9 (ref = CA 19-9 < 37)	1.88	1.04-3.39	0.036a	2.14	0.92-4.99	0.078
CEA/tumor size (ref = low)	2.45	1.46-4.11	0.001a	3.57	1.70-7.52	0.001a

¹These variables were treated as ordinal categorical data;

^aP < 0.05. CEA: Carcinoembryonic antigen; CA 19-9: Carbohydrate antigen 19-9; CI: Confidence interval; ref: Reference.

Table 3 Univariate analysis of prognostic factors for disease-free survival

Variable	Training cohort (n = 371)			Validation cohort (n = 185)
	Hazard ratio	95%CI	P-value	Hazard ratio	95%CI	P-value
Age	1	0.99-1.02	0.572	1.02	0.99-1.04	0.173
Tumor size	1.01	0.91-1.12	0.828	1.12	0.97-1.30	0.128
Sex (ref = male)	1.26	0.85-1.87	0.247	0.75	0.41-1.37	0.353
TNM1 (ref = stage I)	1.9	1.45-2.50	<0.001a	1.6	1.07-2.39	0.023a
Differentiation1 (ref = poor)	0.78	0.58-1.06	0.113	0.6	0.38-0.95	0.031a
Lymphovascular invasion (ref = negative)	2.44	1.45-4.12	0.001a	2.63	1.11-6.22	0.028a
Perineural invasion (ref = negative)	2.17	1.23-3.82	0.008a	1.98	0.78-5.03	0.151
CEA (ref = CEA < 5)	1.55	1.03-2.32	0.034a	1.9	1.05-3.41	0.033a
CA 19-9 (ref = CA 19-9 < 37)	1.43	0.85-2.42	0.177	1.96	0.97-3.96	0.061
CEA/tumor size (ref = low)	1.72	1.10-2.71	0.018a	2.58	1.37-4.85	0.003a

¹These variables were treated as ordinal categorical data;

^aP < 0.05. CEA: Carcinoembryonic antigen; CA 19-9: Carbohydrate antigen 19-9; CI: Confidence interval; ref: Reference.

Table 4 Multivariate analysis of prognostic factors for overall survival and disease-free survival

	Training cohort (n = 371)			Validation cohort (n = 185)
OS	Hazard radio	95%CI	P-value	Hazard radio	95%CI	P-value
Age	1.02	1.00-1.04	0.023a	1.05	1.02-1.09	0.003a
TNM1 (ref = stage I)	1.47	1.04-2.07	0.031a	1.84	1.04-3.24	0.035a
Differentiation1 (ref = poor)	0.57	0.39-0.85	0.006a	0.50	0.28-0.90	0.021a
CEA/tumor size (ref = low)	2.18	1.28-3.73	0.004a	4.83	2.21-10.52	<0.001a
DFS
TNM1 (ref = stage I)	1.75	1.32-2.32	<0.001a	1.43	0.94-2.17	0.091
Lymphovascular invasion (ref = negative)	1.85	1.08-3.16	0.024a	2.45	1.00-6.03	0.05
CEA/tumor size (ref = low)	1.47	0.93-2.33	0.096	2.61	1.38-4.95	0.003a

¹These variables were treated as ordinal categorical data;

^aP < 0.05. CEA: Carcinoembryonic antigen; CI: Confidence interval; ref: Reference; OS: Overall survival; DFS: Disease-free survival.