Prognostic impact of number of examined lymph nodes on survival of patients with appendiceal neuroendocrine tumors

Table 1 Demographics and clinicopathologic characteristics

Factor	Category	mean ± SD/n (%)
Age	mean ± SD, yr	44.59 ± 18.15
Year	1975-1980	141 (3.08)
	1981-1990	128 (2.79)
	1991-2000	274 (5.98)
	2001-2010	1163 (25.38)
	2011-2016	2877 (62.77)
Race	White	3932 (87.34)
	Black	375 (8.33)
	Other	195 (4.33)
Sex	Male	1972 (43)
	Female	2611 (57)
Grade	Grade 1	1857 (72.59)
	Grade 2	408 (15.96)
	Grade 3	248 (9.69)
	Grade 4	45 (1.76)
Histological type	Large cell neuroendocrine carcinoma	6 (0.13)
	Small cell carcinoma	1 (0.02)
	Carcinoid tumor	2266 (49.44)
	Enterochromaffin cell carcinoid	25 (0.55)
	Goblet cell carcinoid	1033 (22.54)
	Mixed adenoneuroendocrine carcinoma	366 (7.99)
	Adenocarcinoid tumor	417 (9.10)
	Neuroendocrine carcinoma	419 (9.14)
	Atypical carcinoid tumor	50 (1.09)
Tumor size	mean ± SD, mm	17.56 ± 19.69
Stage	I	1220 (57.36)
	II	504 (23.70)
	III	270 (12.69)
	IV	133 (6.25)
T stage	Tx	86 (3.86)
	Tis	7 (0.31)
	T1	1290 (57.87)
	T2	194 (8.70)
	T3	446 (20.01)
	T4	204 (9.15)
M stage	M0	2094 (94.07)
	M1	132 (5.93)
N stage	N0	2551 (81.76)
	N1	569 (18.24)
Surgery	Local resection	405 (10.34)
	Colectomy or greater	3513 (89.66)
ELNs	mean ± SD	16.54 ± 10.81
LNR	mean ± SD	0.26 ± 0.28
Survival duration	mean ± SD, mo	64.57 ± 89.96

ELNs: Examined lymph nodes; LNR: Lymph node ratio (the ratio of positive lymph nodes to the total lymph nodes examined).

Table 2 Univariate analysis using Cox proportional hazard model

Factor	Category	HR	95%CI	Log-rank P value
Age	≤ 40 yr	-	-	P < 0.001
	41-65 yr	7.25	5.09-10.32
	≥ 66 yr	16.14	11.08-23.52
Year	1975-1980	-	-	P < 0.001
	1981-1990	3.06	1.56-6.01
	1991-2000	4.72	2.51-8.85
	2001-2010	3.83	2.09-7.02
	2011-2016	1.84	0.98-3.43
Race	White	-	-	P = 0.02
	Other	1.15	0.73-1.83
	Black	1.58	1.20-2.08
Sex	Male	-	-	P = 0.80
	Female	1.02	0.85-1.23
Grade	Grade 1/2	-	-	P < 0.001
	Grade 3/4	19.14	13.63-26.87
Histological type	Carcinoid tumor	-	-	P < 0.001
	Neuroendocrine carcinoma	2.36	1.44-3.88
	Goblet cell carcinoid	4.98	3.61-6.87
	Adenocarcinoid tumor	6.87	4.89-9.64
	Mixed adenoneuroendocrine carcinoma	14.45	10.30-20.27
Tumor size	≤ 2 cm	-	-	P < 0.001
	> 2 cm	8.54	5.99-12.17
Stage	I/II	-	-	P < 0.001
	III/IV	17.12	11.78-24.87
T stage	T1	-	-	P < 0.001
	T2	5.16	1.29-20.64
	T3	17.25	6.09-48.81
	T4	117.44	43.03-320.55
M stage	M0	-	-	P < 0.001
	M1	31.37	22.16-44.39
N stage	N0	-	-	P < 0.001
	N1	8.44	6.69-10.65
Surgery	Local resection	-	-	P < 0.001
	Colectomy or greater	3.47	1.95-6.17
ELNs	≥ 11	-	-	P < 0.001
	≤ 10	1.75	1.37-2.23
LNR	0-0.16	-	-	P < 0.001
	0.17-0.48	3.23	2.25-4.64
	0.49-1	7.70	5.38-11.01

ELNs: Examined lymph nodes; LNR: Lymph node ratio (the ratio of positive lymph nodes to the total lymph nodes examined).

Table 3 The 3-, 5-, and 10-yr cancer-specific survival rates for patients

Patients	3-yr, %	5-yr, %	10-yr, %	Follow-up, mo	Median follow-up, mo	Median survival time, mo
All	91.2	87.5	81.7	0-499	31	-
Stage I	99.7	99.7	-	0-83	23	-
Stage II	98.7	95.5	-	0-83	42	-
Stage III	89.0	82.0	-	0-82	38	-
Stage IV	42.0	25.1	-	0-83	23	30

Median survival is unavailable when there were not half patients dead at the cutoff date.

Table 4 Fourfold contingency table of tumor size and lymph node status

Tumor size	LN status		Total
	N0	N1
≤ 2 cm	1516 (94.0)	97 (6.0)	1613 (100)
> 2 cm	357 (60.6)	232 (39.4)	589 (100)
Total	1873 (85.1)	329 (14.9)	2202 (100)

LN: Lymph node.

Table 5 The 3-, 5-, and 10-yr cancer-specific survival rates by lymph node status and cutoff points of examined lymph nodes

Patients	ELNs	3-yr, %	5-yr, %	10-yr, %	Follow-up, mo	Median follow-up, mo	Median survival, mo
All	≤ 10	83.2	76.1	67.9	0-306	36	-
	≥ 11	90.3	85.5	79.1	0-347	38	-
Node-negative	≤ 6	94.9	86.5	79.3	0-306	28	-
	≥ 7	98.1	95.4	90.1	0-326	43	-
Node-positive	≤ 17	60.7	50.0	40.6	0-345	31	60
	≥ 18	78.4	71.5	61.4	0-347	35	-

Median survival is unavailable when there were not half patients dead at the cutoff date. ELNs: Examined lymph nodes.

Table 6 The 3-, 5-, and 10-yr cancer-specific survival rates for node-positive patients based on lymph node ratio cutoff points

LNR	3-yr, %	5-yr, %	10-yr, %	Follow-up, mo	Median follow-up, mo	Median survival, mo
ALL	67.3	58.4	48.9	0-347	33	-
0-0.16	88.5	80.8	68.9	0-347	45	-
0.17-0.48	59.7	46.2	37.4	1-345	32	46
0.49-1	24.7	17.7	14.2	0-203	16	18

Median survival is unavailable when there were not half patients dead at the cutoff date. LNR: Lymph node ratio (the ratio of positive lymph nodes to the total lymph nodes examined).