Chemotherapy predictors and a time-dependent chemotherapy effect in metastatic esophageal cancer

Table 1 Baseline characteristics of all patients with advanced esophageal cancer who received or did not receive chemotherapy

Variable	All patients (n = 29182)	Chemotherapy received (n = 21911)	No chemo received (n = 7271)
Age
Median (IQR)	64 (56-73)	63 (55-71)	69 (59-79)
Gender
Female	5126 (17.57)	3569 (16.29)	1557 (21.41)
Male	24056 (82.43)	18342 (83.71)	5714 (78.59)
Race
Black	2878 (9.95)	1936 (8.9)	942 (13.12)
Other	1669 (5.77)	1245 (5.72)	424 (5.9)
White	24389 (84.29)	18574 (85.38)	5815 (80.98)
Insurance type
Medicaid	2415 (8.44)	1752 (8.14)	663 (9.36)
Medicare	13412 (46.87)	9263 (43.02)	4149 (58.58)
Not insured	1404 (4.91)	959 (4.45)	445 (6.28)
Other government	459 (1.6)	323 (1.5)	136 (1.92)
Private	10923 (38.17)	9233 (42.88)	1690 (23.86)
Income quartiles for place of residence
Less than $30000	3918 (13.99)	2687 (12.79)	1231 (17.61)
$30000-$34999	5362 (19.15)	3942 (18.77)	1420 (20.31)
$35000-$45999	8066 (28.81)	6081 (28.95)	1985 (28.39)
$46000+	10652 (38.05)	8297 (39.5)	2355 (33.69)
Treatment site
Academic	12955 (45.07)	9856 (45.75)	3099 (43.05)
Non-academic	15786 (54.93)	11686 (54.25)	4100 (56.95)
Geographic location in United States
Midwest	8278 (28.8)	6388 (29.65)	1890 (26.25)
Northeast	6772 (23.56)	5178 (24.04)	1594 (22.14)
South	9509 (33.09)	6977 (32.39)	2532 (35.17)
West	4182 (14.55)	2999 (13.92)	1183 (16.43)
Residence area type
Metro	22465 (80.15)	16883 (80.25)	5582 (79.88)
Rural	641 (2.29)	467 (2.22)	174 (2.49)
Urban	4921 (17.56)	3689 (17.53)	1232 (17.63)
Number of comorbidities1
0	22009 (75.42)	17017 (77.66)	4992 (68.66)
1	5401 (18.51)	3789 (17.29)	1612 (22.17)
≥ 2	1772 (6.07)	1105 (5.04)	667 (9.17)
Year of diagnosis
2004-2009	15715 (53.85)	11588 (52.89)	4127 (56.76)
2010-2014	13467 (46.15)	10323 (47.11)	3144 (43.24)
Grade2
1	633 (2.77)	475 (2.73)	158 (2.89)
2	7926 (34.65)	6099 (35.02)	1827 (33.46)
3	13849 (60.54)	10497 (60.28)	3352 (61.38)
4	467 (2.04)	343 (1.97)	124 (2.27)
AJCC T stage
T0	51 (0.32)	31 (0.24)	20 (0.58)
T1	2624 (16.26)	1889 (14.86)	735 (21.45)
T2	1751 (10.85)	1442 (11.35)	309 (9.02)
T3	7128 (44.18)	6105 (48.04)	1023 (29.86)
T4	4570 (28.33)	3233 (25.44)	1337 (39.03)
pIS	10 (0.06)	8 (0.06)	2 (0.06)
AJCC N stage
Negative	4983 (22.23)	3562 (20.36)	1421 (28.86)
Positive	17435 (77.77)	13933 (79.64)	3502 (71.14)

¹Per Charlson/Deyo[11].

²Grade 1, well-differentiated; grade 2, moderately differentiated; grade 3, poorly differentiated; grade 4, undifferentiated.

Data are presented as number of patients (column %) or median (interquartile range). AJCC: American Joint Committee on Cancer.