Preoperative prediction of perineural invasion of rectal cancer based on a magnetic resonance imaging radiomics model: A dual-center study

Table 2 Characteristics of patients in the training, internal validation and external validation groups, n (%)

Characteristics	Training group (n = 118)		P value	Internal validation group (n = 52)		P value	External validation group (n = 74)		P value
	PNI+ (n = 39)	PNI- (n = 79)		PNI+ (n = 17)	PNI- (n = 35)		PNI+ (n = 25)	PNI- (n = 49)
Sex			0.854			0.882			0.640
Male	25 (64.1)	52 (65.8)		12 (70.6)	24 (68.6)		16 (64.0)	34 (69.4)
Female	14 (35.9)	27 (34.2)		5 (29.4)	11 (31.4)		9 (36.0)	15 (30.6)
Age (yr)	68 (56.5-73)	68 (58.5-75)	0.479	66.59 ± 12.57	64.17 ± 10.32	0.497	65.24 ± 11.70	66.84 ± 9.85	0.562
CEA			0.150			0.027			0.005
Negative (< 5 ng/mL)	23 (59.0)	57 (72.2)		9 (52.9)	30 (85.7)		14 (56.0)	42 (85.7)
Positive (≥ 5 ng/mL)	16 (41.0)	22 (27.8)		8 (47.1)	5 (14.3)		11 (44.0)	7 (14.3)
CA19-9			0.034			0.019			1.000
Negative (< 30 U/mL)	30 (76.9)	72 (91.1)		12 (70.6)	34 (97.1)		23 (92.0)	46 (93.9)
Positive (≥ 30 U/mL)	9 (23.1)	7 (8.9)		5 (29.4)	1 (2.9)		2 (8.0)	3 (6.1)
DIS			0.050			0.444			0.823
High	24 (61.5)	31 (39.2)		9 (52.9)	15 (42.9)		12 (48.0)	22 (44.9)
Mid	3 (7.7)	16 (20.3)		5 (29.4)	9 (25.7)		5 (20.0)	13 (26.5)
Low	12 (30.8)	32 (40.5)		3 (17.6)	11 (31.4)		8 (32.0)	14 (28.6)
mT			0.211			0.885			0.314
mT1-2	3 (7.7)	15 (19.0)		6 (35.3)	10 (28.6)		5 (20.0)	9 (18.4)
mT3	24 (61.5)	47 (59.5)		8 (47.1)	18 (51.4)		14 (56.0)	32 (65.3)
mT4	12 (30.8)	17 (21.5)		3 (17.6)	7 (20.0)		6 (24.0)	8 (16.3)
mN			0.003			0.063			0.028
mN0	5 (12.8)	27 (34.2)		3 (17.6)	18 (51.4)		6 (24.0)	19 (38.8)
mN1	13 (33.3)	33 (41.8)		5 (29.4)	7 (20.0)		7 (28.0)	21 (42.9)
mN2	21 (53.8)	19 (24.1)		9 (52.9)	10 (28.6)		12 (48.0)	9 (18.4)
cM			0.070			1.000			0.064
cM0	34 (87.2)	77 (97.5)		17 (100.0)	34 (97.1)		22 (88.0)	49 (100.0)
cM1	5 (12.8)	2 (2.5)		0 (0.0)	1 (2.9)		3 (12.0)	0 (0.0)
cTNM			1.000			1.000			1.000
Ⅰ	1 (2.6)	29 (36.7)		0 (0.0)	16 (45.7)		0 (0.0)	18 (36.7)
Ⅱ	9 (23.1)	25 (31.6)		5 (29.4)	13 (37.1)		3 (12.0)	12 (24.5)
Ⅲ	25 (64.1)	23 (29.1)		11 (64.7)	5 (14.3)		19 (76.0)	19 (38.8)
Ⅳ	4 (10.3)	2 (2.5)		1 (5.9)	1 (2.9)		3 (12.0)	0 (0.0)
mCRM			0.002			0.374			0.236
Negative	14 (35.9)	52 (65.8)		9 (52.9)	23 (65.7)		15 (60.0)	36 (73.5)
Positive	25 (64.1)	27 (34.2)		8 (47.1)	12 (34.3)		10 (40.0)	13 (26.5)
mEMVI			0.016			0.935			0.009
Negative	15 (38.5)	49 (62.0)		10 (58.8)	21 (60.0)		10 (40.0)	35 (71.4)
Positive	24 (61.5)	30 (38.0)		7 (41.2)	14 (40.0)		15 (60.0)	14 (28.6)
Histological grade			0.000			0.920			0.894
Well differentiated	4 (10.3)	27 (34.2)		2 (11.8)	11 (31.4)		4 (16.0)	13 (26.5)
Moderately differentiated	26 (66.7)	49 (62.0)		12 (70.6)	23 (65.7)		18 (72.0)	34 (69.4)
Poorly differentiated	9 (23.1)	3 (3.8)		3 (17.6)	1 (2.9)		3 (12.0)	2 (4.1)

P value represents analysis of PNI-positive and PNI-negative datasets between each group. PNI: Perineural infiltration; CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9; mCRM: MRI-based circumferential resection margin; mEMVI: MRI-based extramural vascular invasion; mT: MRI T stage; mN: MRI N stage; cM: Clinical M stage; cTNM: Clinical TNM stage; DIS: The distance between tumor and anal margin, Low (0-5 cm from the anal verge), middle (5.1-10 cm from the anal verge), and high (10.1-15 cm from the anal verge).