Tumor Primary Location May Affect Metastasis Pattern for Patients with Stage IV NSCLC: A Population-Based Study

Table 1

Characteristics of patients from SEER database according to different variables.

Variables	Number	%
Age
<65	7935	41.1
≥65	11,360	58.9
Race
White	14,931	77.4
Black	2685	13.9
Others	1679	8.7
Sex
Female	8571	44.4
Male	10,724	55.6
Histology
Adenocarcinoma	13,745	71.2
Squamous cell carcinoma	5550	28.8
T stage
T1	2211	11.5
T2	5558	28.8
T3	4964	25.7
T4	6562	34.0
N stage
N0	4712	24.4
N1	1591	8.2
N2	9110	47.2
N3	3882	20.1
Primary site
Main bronchus	1054	5.5
Upper lobe	11,401	59.1
Middle lobe	956	5.0
Lower lobe	5640	29.2
Overlapping lesion	244	1.3
Bone metastasis
Yes	7230	37.5
No	12,065	62.5
Brain metastasis
Yes	5074	26.3
No	14,221	73.7
Liver metastasis
Yes	3129	16.2
No	16,166	83.8
Lung metastasis
Yes	5976	31.0
No	13,319	69.0