Table 1.

Self-reported baseline and clinical characteristics of study subjects, the PLCO Cancer Screening Trial, 1993–2001

Cases (N = 370)Controls (N = 493)
n (%) or mean (SD)n (%) or mean (SD)P
Age group, y
 ≤5983 (22.4)98 (19.9)0.78
 60–64127 (34.3)170 (34.5)
 65–6993 (25.1)126 (25.6)
 70–7467 (18.1)99 (20.1)
Male196 (53.0)290 (58.8)0.09
White327 (88.4)432 (87.6)0.74
College graduated or higher113 (30.6)188 (38.4)0.02
First-degree family history of colorectal cancer50 (13.5)59 (12.0)0.50
Current cigarette smoker41 (11.1)52 (10.6)0.86
Former cigarette smoker162 (43.8)225 (45.6)
Regular aspirin or ibuprofen use (≥4/mo)218 (58.9)304 (61.7)0.41
Current hormone use among females88 (44.0)112 (50.9)0.21
Former hormone use among females33 (16.5)39 (17.7)
Body mass index, kg/m227.5 (4.6)27.5 (5.0)0.87
Alcohol, g/d13.8 (29.4)11.5 (20.4)0.23
Natural food folate, μg/d302.0 (121.2)314.5 (125.8)0.17
Fortified food folate, μg/d163.7 (91.8)181.9 (122.3)0.02
Total folate equivalents (food and supplements), μg/d1,056.8 (722.8)1,088.8 (727.8)0.54
Vitamin B6 (food and supplements), mg/d2.37 (0.9)2.47 (1.1)0.16
Vitamin B12 (food and supplements), mg/d5.7 (3.0)5.9 (3.4)0.40
Methionine (food), g/d1.7 (0.7)1.7 (0.7)0.46
Distal carcinoma238 (51.5)
 Stage I82 (16.1)
 Stage II184 (39.8)
 Stage III111 (24.0)
 Stage IV93 (20.1)