Radiomics for differentiating tumor deposits from lymph node metastasis in rectal cancer

Table 1 Baseline and clinical characteristics of the included patients

Characteristics	TDs+LNM-(n = 89)	LNM+TDs– (n = 115)	P value	Training set (n = 163)	Validation set (n = 41)	P value
Age (mean ± SD, yr)	59 ± 12	61 ± 12	0.268	60 ± 12	60 ± 11	0.965
Gender (man/woman)	49/40	63/52	0.969	94/69	18/23	0.113
Location (middle-low/high)	65/24	74/41	0.187	107/56	32/9	0.128
Neoadjuvant therapy (+/-)	34/55	43/72	0.906	62/101	15/26	0.864
CEA (+/-) (positive ≥ 5 ng/mL)	42/47	43/72	0.159	75/88	10/31	0.012
CA19-9 (+/-) (positive ≥ 30 U/mL)	23/66	18/97	0.072	34/129	7/34	0.589
CA125 (+/-) (positive ≥ 24 U/mL)	13/76	14/101	0.611	21/142	6/35	0.767
pT stage (T1/T2/T3/T4)	0/9/70/10	4/12/93/6	0.063	4/17/127/15	0/4/36/1	0.894
pN stage (1a/1b/1c/2a/2b)	0/0/89/0/0	52/39/0/15/9	< 0.001	37/33/71/13/9	15/6/18/2/0	0.115
Histologic EMVI (+/-)	33/56	16/99	< 0.001	41/122	8/33	0.450
Histologic grade (G1/G2/G3)	1/63/25	0/76/39	0.299	0/113/50	1/26/14	0.901
Peritumoral nodule
Shape (irregular/regular)	12/77	2/113	0.003	11/152	3/38	0.898
Spiculation (+/-)	7/82	2/113	0.077	7/156	2/39	0.871
Size (mm2) (median)	72.7	41.2	< 0.001	54	43	0.886
CT value (HU)	61 ± 22	65 ± 23	0.258	64 ± 23	63 ± 23	0.858
Rad-score 1 (median)	0.71	0.39	< 0.001	0.44	0.71	0.002
Rad-score 2 (median)	0.89	0.13	< 0.001	0.39	0.62	0.561

Rad-score 1: Rad-score of the main tumor; Rad-score 2: Rad-score of the largest peritumoral nodule; CT: Computed tomography; TDs: Tumor deposits; LNM: Lymph node metastasis; CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9; CA125: Carbohydrate antigen 125; pT stage: Pathological T stage; pN stage: Pathological N stage; EMVI: Extramural vascular invasion.

Table 2 Univariate and multivariate logistic regression analysis

Variables	Univariate		Multivariate
	OR	P value	OR	P value
Age	0.995	0.693	-	-
Gender	0.820	0.534	-	-
Location	0.819	0.282	-	-
CEA	1.546	0.171	-	-
CA19-9	1.613	0.217	-	-
CA125	1.503	0.384	-	-
Peritumoral nodule
Shape	14.918	0.011	0.915	0.948
Spiculated (+/-)	8.400	0.051	-	-
Size (mm2)	1.009	0.001	0.999	0.314
CT value (HU)	0.994	0.364	-	-
Rad-score 1	2.946	< 0.001	3.267	< 0.001
Rad-score 2	11.979	< 0.001	14.396	< 0.001

Rad-score 1: Rad-score of the main tumor; Rad-score 2: Rad-score of the largest peritumoral nodule; CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9; CA125: Carbohydrate antigen 125; CT: Computed tomography; OR: Odds ratio.

Table 3 Comparisons of the models in the training, validation, and mixed groups

	Training set				Validation set				Mixed group
	AUC	SEN	SPE	P value	AUC	SEN	SPE	P value	SEN	SPE	Accuracy
Rad-score 1	0.768 (95%CI: 0.695-0.830)	66.2%	70.7%	< 0.001	0.700 (95%CI: 0.537-0.833)	77.8%	47.8%	0.032	-	-	-
Combined model	0.955 (95%CI: 0.910-0.981)	83.1%	88.0%	0.134	0.930 (95%CI: 0.805-0.986)	94.4%	82.6%	0.594	66.6%	73.3%	70.0%
Rad-score 2	0.940 (95%CI: 0.892-0.971)	83.1%	84.8%		0.918 (95%CI: 0.789-0.981)	83.3%	82.6%		73.3%	66.6%	70.0%

The mixed group consisted of 15 double-positive (TDs⁺LNM⁺) and 15 single-positive (11 TDs⁺LNM^- and 4 LNM⁺TDs^-) patients. P value: compared with Rad-score 2 by DeLong’s test. Rad-score 1: Rad-score of the main tumor; Rad-score 2: Rad-score of the largest peritumoral nodule; TDs: Tumor deposits; LNM: Lymph node metastasis; AUC: Area under the curve; SEN: Sensitivity; SPE: Specificity.

Table 4 Subgroup analyses of the models in single-positive patients

	Rad-score 1			Rad-score 2			P value
Subgroups	AUC	SEN (%)	SPE (%)	AUC	SEN (%)	SPE (%)
nCRT
With (n = 77)	0.740 (95%CI: 0.628-0.833)	73.5%	74.4%	0.897 (95%CI: 0.806-0.954)	73.5%	90.7%	0.014
Without (n = 127)	0.753 (95%CI: 0.668-0.825)	60%	86.1%	0.957 (95%CI: 0.905-0.985)	89.1%	93.1%	< 0.001
Location
Mid-low (n = 139)	0.782 (95%CI: 0.704-0.848)	75.4%	62.2%	0.931 (95%CI: 0.875-0.967)	86.2%	82.4%	< 0.001
High (n = 65)	0.643 (95%CI: 0.515-0.758)	54.2%	73.2%	0.941 (95%CI: 0.853-0.984)	83.3%	85.4%	< 0.001
Number of TDs	1-2 (n = 50)	≥ 3 (n = 39)	P = 0.838	1-2 (n = 50)	≥ 3 (n = 39)	P = 0.309
Value	0.64 ± 0.24	0.65 ± 0.22		0.83 ± 0.22	0.77 ± 0.26

Rad-score 1: Rad-score of the main tumor; Rad-score 2: Rad-score of the largest peritumoral nodule; TDs: Tumor deposits; AUC: Area under the curve; SEN: Sensitivity; SPE: Specificity; nCRT: Neoadjuvant chemoradiotherapy.