Table 1. Demographic and tumor related features of patients diagnosed between 2000 and 2014 at 18 SEER sites, and 2 and 5 years relative survival rates of each groups.

Variable	Patients, n (%)	RSR (2 years), %	RSR (5 years), %	P value
Overall	1,138 (100.00)	87.30±1.20	72.00±2.00
Age (years)
≤50	227 (19.95)	92.60±2.00	80.20±3.20	ref
>50	911 (80.05)	86.20±1.40	70.20±2.20	0.006
Gender
Male	589 (51.76)	86.20±1.70	71.70±2.70	ref
Female	549 (48.24)	88.50±1.60	72.30±2.80	0.81
Year of diagnosis
≤2007	285 (25.04)	82.10±2.50	66.50±3.20	ref
≥2008	853 (74.96)	89.30±1.30	74.70±2.60	0.01
Race
White	972 (85.41)	87.90±1.30	72.60±2.10	ref
Black/others	166 (14.59)	85.00±3.50	72.00±5.40	0.43
Tumor location
Duodenum	75 (6.59)	63.7±5.90	51.50±6.70	ref
Jejunum	78 (6.85)	85.20±5.00	72.30±7.70	0.006
Ileum	633 (55.62)	91.30±1.40	76.40±2.60	<0.001
NOS	352 (30.93)	85.80±2.20	67.80±3.70	<0.001
Tumor size (cm)
≤2	419 (36.81)	89.90±1.20	74.80±2.20	ref
>2	505 (44.37)	71.60±4.30	59.20±5.50	<0.001
Missing	214 (18.80)	NA	NA	NA
Histology
Neuroendocrine	529 (46.49)	83.00±1.90	65.10±3.00	ref
Carcinoid	580 (50.97)	92.60±1.40	79.30±2.60	<0.001
Other	29 (2.55)	73.80±10.20	62.00±12.40	0.60
Liver metastasis
No	203 (17.83)	87.80±3.10	NA	ref
Yes	464 (40.77)	88.90±1.80	NA	0.87
Missing	471 (41.38)	NA	NA	NA
Grade
I	814 (71.53)	92.10±0.20	78.50±2.20	ref
II	233 (20.47)	87.00±2.70	64.30±4.70	0.003
III/IV	91 (8.00)	47.40±5.70	33.80±6.10	<0.001
Surgery
No surgery	126 (11.07)	62.80±4.70	45.30±6.0	ref
Local resection	750 (65.91)	91.20±1.30	76.00±2.40	<0.001
Radical resection	262 (23.02)	88.20±2.30	73.70±3.70	<0.001

RSR, relative survival rate; ref, reference; NOS, not otherwise specified.