Table 1. The patient characteristics of the entire cohort.

Variables	No. of patients [%]
Age (years)
≤60	742 [30]
60 to 70	899 [36]
>70	860 [34]
Sex
Male	1,214 [49]
Female	1,287 [51]
Race
White	2,008 [80]
Black	244 [10]
Other/unknown	249 [10]
Histology
Adenocarcinoma	1,891 [76]
Squamous cell cancer	610 [24]
T stage
T1–2	1,902 [76]
T3–4	599 [24]
Laterality
Right	1,396 [56]
Left	1,105 [44]
No. of nodes sampled
>10	1,428 [57]
≤10	1,073 [43]
No. of positive lymph nodes
1 to 3	1,483 [59]
≥4	1,018 [41]
Chemotherapy
Yes	1,923 [77]
No	578 [23]
Postoperative radiotherapy
Yes	1,049 [42]
No	1,452 [58]
Type of surgery
Lobectomy	2,285 [91]
Pneumonectomy	216 [9]