Log odds of positive lymph nodes is a better prognostic factor for oesophageal signet ring cell carcinoma than N stage

Table 1 Clinical and pathological characteristics of patients and results of univariate analysis for overall survival

Variable	No. of patients (%)	HR	95%CI	P value
Sex				0.488
Female	28 (10.8)	Reference
Male	231 (89.2)	1.199	0.717-2.006	0.488
Age, yr				0.776
≤ 60	88 (34.0)	Reference
61-70	112 (43.2)	0.942	0.671-1.322	0.728
≥ 71	59 (22.8)	1.082	0.729-1.606	0.695
Marital status				0.152
Married	187 (72.2)	Reference
Single	57 (22.0)	1.400	0.996-1.968	0.053
Unknown	15 (5.8)	1.151	0.584-2.266	0.685
Insurance				0.005
Insured	217 (83.8)	Reference
Uninsured	4 (1.5)	5.272	1.904-14.599	0.001
Unknown	38 (14.7)	0.918	0.608-1.358	0.683
Race				0.087
Hispanic (all races)	19 (7.3)	Reference
Non-Hispanic American Indian/Alaska Native	2 (0.8)	0.358	0.046-2.762	0.324
Non-Hispanic Asian or Pacific Islander	5 (1.9)	1.229	0.395-3.818	0.722
Non-Hispanic Black	10 (3.9)	2.293	0.987-5.326	0.054
Non-Hispanic White	223 (86.1)	0.962	0.534-1.734	0.898
Grade				0.136
I + II	12 (4.6)	Reference
III + IV	214 (82.6)	0.978	0.499-1.918	0.949
Unknown	33 (12.7)	0.595	0.267-1.326	0.204
TNM stage				0.000
I	34 (13.1)	Reference
II	59 (22.8)	1.919	1.031-3.573	0.040
III	130 (50.2)	2.931	1.662-5.168	0.000
IV	36 (13.9)	4.936	2.610-9.334	0.000
T stage				0.048
T1	51 (19.7)	Reference
T2	30 (11.6)	1.757	0.992-3.112	0.053
T3	164 (63.3)	1.705	1.120-2.596	0.013
T4	14 (5.4)	2.334	1.121-4.861	0.024
N stage				0.000
N0	86 (33.2)	Reference
N1	100 (38.6)	1.841	1.263-2.682	0.001
N2	47 (18.1)	2.666	1.697-4.189	0.000
N3	26 (10)	3.836	2.316-6.353	0.000
M stage				0.058
M0	246 (95)	Reference
M1	13 (5.0)	1.809	0.981-3.337	0.058
LODDS				0.000
LODDS1 (4.55 ≤ LODDS ≤ 1.90)	134 (51.7)	Reference
LODDS2 (1.89 ≤ LODDS ≤ 0.15)	99 (38.2)	1.864	1.353-2.569	0.000
LODDS3 (0.16 ≤ LODDS ≤ 4.27)	26 (10)	4.204	2.656-6.655	0.000
Radiation therapy				0.085
No radiation and/or cancer-directed surgery	67 (25.9)	Reference
Radiation prior to surgery	162 (62.5)	1.010	0.710-1.435	0.958
Radiation after surgery	25 (9.7)	1.779	1.061-2.983	0.029
Radiation before and after surgery	5 (1.9)	1.672	0.516-5.421	0.392
Chemotherapy				0.719
No or unknown	49 (18.9)	Reference
Yes	210 (81.1)	1.073	0.730-1.578	0.719

LODDS: Log odds of positive lymph nodes; NOS: Not otherwise specified.

Table 2 Multivariable analysis of overall survival with different classifications of lymph nodes

Variable	Model 1 (N stage)		Model 2 (LODDS)
	HR (95%CI)	P value	HR (95%CI)	P value
Insurance		0.008		0.100
Insured	Reference		Reference
Uninsured	5.170 (1.817-14.711)	0.002	3.045 (1.031-8.992)	0.044
Unknown	0.921 (0.602-1.409)	0.705	0.871 (0.570-1.331)	0.525
Race		0.169		0.189
Hispanic (all races)	Reference		Reference
Non-Hispanic American Indian/Alaska Native	0.537 (0.067-4.315)	0.559	0.441 (0.054-3.577)	0.443
Non-Hispanic Asian or Pacific Islander	2.286 (0.699-7.476)	0.171	2.972 (0.896-9.864)	0.075
Non-Hispanic Black	2.554 (1.062-6.144)	0.036	2.255 (0.900-5.649)	0.083
Non-Hispanic White	1.334 (0.705-2.521)	0.376	1.486 (0.786-2.811)	0.223
TNM stage		0.486		0.030
I	Reference		Reference
II	1.776 (0.739-4.272)	0.199	2.549 (1.141-5.695)	0.023
III	1.527 (0.399-5.852)	0.537	3.466 (1.518-7.917)	0.003
IV	1.270 (0.173-9.334)	0.814	3.479 (1.197-10.112)	0.022
T stage		0.460		0.402
T1	Reference		Reference
T2	1.472 (0.644-3.362)	0.359	1.013 (0.493-2.085)	0.971
T3	1.063 (0.494-2.291)	0.875	0.699 (0.370-1.321)	0.270
T4	1.580 (0.521-4.797)	0.419	0.900 (0.372-2.178)	0.815
N stage		0.122
N0	Reference
N1	1.759 (0.810-3.817)	0.153
N2	2.415 (1.029-5.665)	0.043
N3	4.572 (1.044-20.021)	0.044
M stage		0.304		0.523
M0	Reference		Reference
M1	2.027 (0.527-7.799)	0.304	1.354 (0.534-3.433)	0.523
LODDS				0.001
4.55 ≤ LODDS ≤ 1.90			Reference
1.89 ≤ LODDS ≤ 0.15			1.742 (1.223-2.483)	0.002
0.16 ≤ LODDS ≤ 4.27			3.390 (1.620-7.093)	0.001
Radiation therapy		0.305		0.389
No radiation and/or cancer-directed surgery	Reference		Reference
Radiation prior to surgery	0.756 (0.503-1.134)	0.176	0.771 (0.515-1.153)	0.205
Radiation after surgery	1.037 (0.571-1.883)	0.906	0.998 (0.557-1.787)	0.994
Radiation before and after surgery	1.540 (0.455-5.218)	0.488	1.491 (0.444-5.008)	0.518

LODDS: Log odds of positive lymph nodes.

Table 3 Prognostic performance of different lymph node staging systems for overall survival

Model	C-Index	P value	AIC	P value
Model 1 (N stage)	0.656	< 0.001	1697.519	< 0.001
Model 2 (LODDS)	0.673	< 0.001	1688.824	< 0.001

AIC: Akaike information criterion; C-Index: Harrel’s concordance index; LODDS: Log odds of positive lymph nodes.

Table 4 Prognostic performance of log odds of positive lymph nodes and N stage for overall survival in validation cohort

Variable	C-Index	P value	AIC	P value
N stage	0.648	0.030	770.094	< 0.001
LODDS	0.654	0.029	766.830	< 0.001

AIC: Akaike information criterion; C-Index: Harrell concordance index; LODDS: Log odds of positive lymph nodes.