Table 1. Frequency distributions of selected variables in CRC patients and cancer-free controls.

Variables	1001 Patients (n, %)		1005 Controls (n, %)		P a
Age (years)					0.4831
<50	233	23.3	231	23.0
50–60	277	27.7	302	30.0
>60	491	49.0	472	47.0
Sex					0.9487
Male	604	60.3	605	60.2
Female	397	39.7	400	39.8
Smoking status					0.1964
Ever	482	48.1	455	45.3
Never	519	51.9	550	54.7
Alcohol drinking					<.0001
Ever	456	45.5	237	23.6
Never	545	54.5	768	76.4
Family history of cancer					0.0122
Yes	115	11.5	82	8.2
No	886	88.5	923	91.8
BMI(kg/m2)					0.0290
<18.5	63	6.3	39	3.9
18.5–24.0	662	66.1	702	69.8
>24.0	276	27.6	264	26.3
Tumor site
Right colon	169	16.9
Left colon	309	30.9
Rectum	523	52.2
Tumor Stages
I	171	17.1
II	320	31.9
III	345	34.5
IV	165	16.5

^a P values for a two-sided χ² test.