Table 1. Distribution of selected variables between the clear cell renal cell carcinoma cases and control subjects.

Variables	Cases (n = 859)		Controls (n = 1005)		P-valuea
	N	%	N	%
Age (years) (mean ± SD)	57.0±11.7		57.2±12.4		0.758
BMI (kg/m2) (mean ± SD)	24.2±2.9		23.8±3.2		0.003
Gender
Male	557	64.8	688	68.5	0.098
Female	302	35.2	317	31.5
Smoking status
Never	530	61.7	666	66.3	0.040
Ever	329	38.3	339	33.7
Drinking status
Never	619	72.1	757	75.3	0.110
Ever	240	27.9	248	24.7
Hypertension
No	522	60.8	675	67.2	<0.001
Yes	337	39.2	251	25.0
Diabetes
No	748	87.6	870	86.6	<0.001
Yes	111	12.4	56	5.6
Clinical stage
I	577	67.2
II	170	19.8
III	57	6.7
IV	55	6.4
Grade
I	176	20.5
II	470	54.7
III	171	19.9
IV	42	4.9

^aStudent's t-test for age and BMI distributions between cases and controls; two-sided χ2-test for others selected variables between cases and controls.