Table 1.

The characteristics of case and control.

Variable	Case	%	Control	%	p
Total	506		507
Gender					0.521a
Male	374	73.9%	375	73.96%
Female	132	26.1%	132	26.04%
Age (years)	63.69 ± 9.26		63.51 ± 7.76		0.448b
< 64	237	46.8%	266	52.50%
≥ 64	269	53.2%	241	47.50%
BMI (kg/m2)
≥ 24	72	14.2%	123	24.3%
< 24	418	82.6%	108	21.3%
Missing	16	3.2%	276	54.4%
Smoking
Yes	233	46.0%	243	47.9%
No	267	52.8%	264	52.1%
Missing	6	1.2%
Drinking
Yes	119	23.5%	243	47.9%
No	345	68.2%	264	52.1%
Missing	42	8.3%
Stage
I & II	225	44.5%
III & IV	141	27.9%
Missing	140	27.7%
LNM
Yes	174	34.4%
No	181	35.8%
Missing	151	29.8%

BMI, body mass index; LNM, lymph node metastasis.

^a p values was calculated by chi-square tests;.

^b p value was calculated by Student’s t tests.