Glutathione-S-transferase (GSTM1, GSTT1) and the risk of gastrointestinal cancer in a Korean population

Table 1 Demographic characteristics of subjects n (%)

Characteristics	Controls	GC	CRC
No.	1699	2213	1829
Age, mean (yr, range)	52.2 (20-74)	60.2 (21-87)a	61.9 (22-88)c
≤ 65 yr	1320 (77.7)	1314 (59.4)	985 (53.9)
> 65 yr	379 (22.3)	899 (40.6)a	844 (46.1)c
Sex
Male	820 (48.3)	1510 (68.2)	1149 (62.8)
Female	879 (51.7)	703 (31.8)a	680 (37.2)c
Smoking
Never-smokers	1000 (58.8)	1127 (50.9)	1137 (62.2)
Ever-smokers	654 (38.5)	997 (45.1)a	582 (31.8)c
Missing	45 (2.6)	89 (4.0)	110 (6.0)
Drinking
Never drinkers	825 (48.6)	1198 (54.1)	1084 (59.3)
Current drinkers	832 (49.0)	921 (41.6)a	623 (34.1)c
Missing	42 (2.5)	94 (4.3)	122 (6.7)
GSTT1
Null type	858 (50.5)	1172 (53.0)	950 (51.9)
Wild type	841 (49.5)	1041 (47.0)	879 (48.1)
GSTM1
Null type	923 (54.3)	1225 (55.4)	1004 (54.9)
Wild type	776 (45.7)	988 (44.6)	825 (45.1)
TNM stage
I		1138 (51.4)	291 (15.9)
II		305 (13.8)	547 (29.9)
III		290 (13.1)	615 (33.6)
IV		386 (17.4)	230 (12.6)
Unspecified stage		94 (4.2)	147 (8.0)
Tumor site
Cardiac		106 (4.8)	833 (45.5) (colon)
Non-cardiac		2093 (94.6)	996 (54.5) (rectum)
Unspecified site		14 (0.6)
Histological type
Intestinal		1286 (58.1)
Diffuse		561 (25.4)
Mixed		240 (10.8)
Unspecified type		126 (5.7)

^aGC compared with control, P < 0.05;

^cCRC compared with control, P < 0.05. GC: Gastric cancer; CRC: Colorectal cancer; GSTT1: Glutathione S-transferase theta; GSTM1: Glutathione S-transferase mu.