Beyond the tumor region: Peritumoral radiomics enhances prognostic accuracy in locally advanced rectal cancer

Table 1 Clinicoradiological characteristics of patients, n (%)

Variable	Total (n = 409)	Training (n = 273)	Validation (n = 136)	1P value
Age (years), median (IQR)	56 (49-64)	58 (49-64)	56 (47-64)	0.219
Sex				> 0.999
Male	276 (67.5)	184 (67.4)	92 (67.6)
Female	133 (32.5)	89 (32.6)	44 (32.4)
BMI				0.351
< 18.5	45 (11.0)	31 (11.4)	14 (10.3)
18.5-24	178 (43.5)	112 (41.0)	66 (48.5)
> 24	186 (45.5)	130 (47.6)	56 (41.2)
CEA level (ng/mL)				0.625
< 5	222 (54.3)	151 (55.3)	71 (52.2)
≥ 5	187 (45.7)	122 (44.7)	65 (47.8)
CA199 level (U/mL)				0.695
< 35	282 (68.9)	186 (68.1)	96 (70.6)
≥ 35	127 (31.1)	87 (31.9)	40 (29.4)
NCRT regimen				0.952
Capecitabine + RT	173 (42.3)	114 (41.8)	59 (43.4)
CapeOx + RT	230 (56.2)	155 (56.8)	75 (55.1)
Other	6 (1.5)	4 (1.5)	2 (1.5)
Adjuvant chemotherapy				> 0.999
No	104 (25.4)	69 (25.3)	35 (25.7)
Yes	305 (74.6)	204 (74.7)	101 (74.3)
Clinical T stage				0.914
cT2	29 (7.1)	20 (7.3)	9 (6.6)
cT3	253 (61.9)	167 (61.2)	86 (63.2)
cT4	127 (31.1)	86 (31.5)	41 (30.1)
Clinical N stage				0.446
cN0	65 (15.9)	45 (16.5)	20 (14.7)
cN1	192 (46.9)	125 (45.8)	67 (49.3)
cN2	99 (24.2)	63 (23.1)	36 (26.5)
cNx	53 (13.0)	40 (14.7)	13 (9.6)
Overall clinical stage				0.643
II	65 (15.9)	45 (16.5)	20 (14.7)
III	344 (84.1)	228 (83.5)	116 (85.3)
Tumor location (cm)				0.950
≤ 5	166 (40.6)	111 (40.7)	55 (40.4)
5.1-10	221 (54.0)	148 (54.2)	73 (53.7)
> 10	22 (5.4)	14 (5.1)	8 (5.9)
Circumferential tumor extent				0.062
1/4-2/4	45 (11.0)	37 (13.6)	8 (5.9)
3/4	103 (25.2)	68 (24.9)	35 (25.7)
4/4	261 (63.8)	168 (61.5)	93 (68.4)
MRF status				0.781
Negative	187 (45.7)	123 (45.1)	64 (47.1)
Positive	222 (54.3)	150 (54.9)	72 (52.9)
EMVI				0.070
Negative	274 (67.0)	191 (70.0)	83 (61.0)
Positive	135 (33.0)	82 (30.0)	53 (39.0)
ypT stage				0.644
ypT 0-2	228 (55.7)	150 (54.9)	78 (57.4)
ypT 3-4	181 (44.3)	123 (45.1)	58 (42.6)
ypN stage				0.027a
ypN0	331 (80.9)	231 (84.6)	100 (73.5)
ypN1	67 (16.4)	36 (13.2)	31 (22.8)
ypN2	11 (2.7)	6 (2.2)	5 (3.7)
TRG				0.246
1-2	218 (53.3)	140 (51.3)	78 (57.4)
3-5	191 (46.7)	133 (48.7)	58 (42.6)

¹P value for the comparison of training and validation sets using the χ² test for categorical variables or the Mann-Whitney U test for continuous variables.

^aP < 0.05.

BMI: Body mass index; CA199: Carbohydrate antigen 199; CapeOx: Capecitabine plus oxaliplatin; CEA: Carcinoembryonic antigen; EMVI: Extramural vascular invasion; IQR: interquartile range; MRF: Mesorectal fascia; NCRT: Neoadjuvant chemoradiotherapy; RT: Radiotherapy; TRG: Tumor regression grade; ypT stage: Pathological T stage after neoadjuvant chemoradiotherapy; ypN stage: Pathological N stage after neoadjuvant chemoradiotherapy.