Table 1.

Clinicopathologic characteristics of young non-small cell lung cancer patients under 40 years old according to age at diagnosis (18–30 and 31–40)

Variables	The “18–30” age group	The “31–40” age group	P
Gender			0.554
Female	211 (49.2%)	2000 (47.7%)
Male	218 (50.8%)	2194 (52.3%)
Race
White	301 (70.2%)	2902 (69.2%)	0.679
African American	55 (12.8%)	753 (18.0%)	0.008
Others	73 (17.0%)	539 (12.9%)	0.015
Year of diagnosis			<0.001
1988–1999	85 (19.8%)	1521 (36.3%)
2000–2012	344 (80.2%)	2673 (63.7%)
Histology
Adenocarcinoma	284 (66.2%)	2527 (60.3%)	0.016
Squamous	49 (11.4%)	457 (10.9%)	0.740
Large cell	20 (4.7%)	347 (8.3%)	0.008
Adenosquamous	10 (2.3%)	76 (1.8%)	0.449
NOS	66 (15.4%)	764 (18.2%)	0.145
Undifferentiated	0 (0)	23 (0.5%)	0.265
Stage
I	67 (15.6%)	446 (10.6%)	0.002
II	14 (3.3%)	144 (3.4%)	0.853
III	75 (17.5%)	1080 (25.8%)	<0.001
IV	273 (63.6%)	2524 (60.2%)	0.163
Surgery			0.004
Yes	156 (36.4%)	1205 (28.7%)
No	270 (62.9%)	2957 (70.5%)
Unknown	3 (0.7%)	32 (0.8%)
Radiation			<0.001
Yes	179 (41.7%)	2358 (56.2%)
No	246 (57.3%)	1743 (41.6%)
Unknown	4 (0.9%)	93 (2.2%)
Lymph nodes removed			0.022
0	261 (60.8%)	2783(66.4%)
1–5*	62 (14.5%)	542(12.9%)
No less than 6	67 (15.6%)	464 (11.1%)
Unknown	39 (9.1%)	405 (9.6%)
Lymph nodes positive			0.033
0	76 (17.7%)	570 (13.6%)
1*	32 (7.5%)	315 (7.5%)
No less than 2	30 (7.0%)	220 (5.2%)
Unknown	291 (67.8%)	3089(73.7%)
Tumor Grade			<0.001
Well differentiated	43 (10.0%)	169 (4.0%)	<0.001
Moderately differentiated	55 (12.8%)	560 (13.4%)	0.823
Poorly differentiated	124 (28.9%)	1498 (35.7%)	0.005
Undifferentiated; anaplastic	24 (5.6%)	257 (6.1%)	0.750
Unknown	183 (42.7%)	1710 (40.8%)	0.471
Second cancer deaths	31 (7.2%)	250 (6.0%)	0.289

Abbreviations: NOS, not otherwise specified

Note: *The median number of lymph nodes removed was 5. The median number of lymph nodes positive was 1.