Table 1. General characteristics of study population.

Characteristic	N=629 (%)
Age, years
<70	508 (80.8)
≥70	121 (19.2)
Gender
Male	365 (58.0)
Female	264 (42.0)
Histological type
Squamous cell carcinoma	142 (22.6)
Non-squamous cell carcinoma	441 (70.1)
Others	45 (7.2)
Unknown	1 (0.2)
Size, cm
<3	281 (44.7)
3–5	193 (30.7)
5–7	98 (15.6)
≥7	49 (7.8)
Unknown	8 (1.3)
pN stage
pN0	378 (60.1)
pN1	84 (13.4)
pN2	139 (22.1)
Unknown	28 (4.5)