Table 2.

Genotype frequencies in cases and controls and colorectal adenoma risks

GeneGenotypeCases (N)Controls (N)Odds ratio* (95% confidence interval)
CYP1A1*1/*1864 (94.3%)895 (91.7%)1.0
*1/*2C52 (5.7%)80 (8.2%)0.7 (0.5-0.9)
*2C/*2C0 (0%)1 (0.1%)
*2C carrier52 (5.7%)81 (8.3%)0.7 (0.5-0.9)
CYP1A1*1/*1745 (84.1%)738 (83.2%)1.0
*1/*2A138 (15.6%)142 (16.0%)1.0 (0.8-1.2)
*2A/*2A3 (0.3%)7 (0.8%)0.4 (0.1-1.7)
*2A carrier141 (15.9%)149 (16.8%)0.9 (0.7-1.2)
CYP2E1*1/*1865 (95.0%)918 (94.5%)1.0
*1/*5B46 (5.0%)53 (5.5%)0.9 (0.6-1.4)
*5B/*5B0 (0%)0 (0%)
GSTM1Null (0/0)556 (64.7%)552 (62.4%)1.0
A/A or A/0150 (17.5%)179 (20.2%)0.8 (0.7-1.1)
B/B or B/0131 (15.3%)135 (15.3%)1.0 (0.7-1.3)
A/B22 (2.5%)19 (2.1%)1.2 (0.6-2.2)
GSTM1Non-null303 (35.3%)333 (37.6%)1.0
Null556 (64.7%)552 (62.4%)1.1 (0.9-1.4)
GSTM3A/A649 (70.9%)692 (70.8%)1.0
A/B246 (26.9%)255 (26.1%)1.0 (0.8-1.3)
B/B21 (2.2%)30 (3.1%)0.8 (0.4-1.3)
*B carrier267 (29.1%)285 (29.2%)1.0 (0.8-1.2)
GSTT1Non-null644 (83.9%)672 (82.6%)1.0
Null124 (16.1%)142 (17.4%)0.9 (0.7-1.2)
  • NOTE: Absolute numbers (N) differ slightly due to differences in efficacy of genotyping protocols.

  • * Odds ratios were adjusted for age, sex, and screening center.

  • Reference category.

  • Because of the low frequency of CYP1A1*2A and *2C homozygotes, a “carrier” category was created that included CYP1A1*1/*2A and CYP1A1*2A/*2A as a CYP1A1*2A carrier genotype, CYP1A1*1/*2C and CYP1A1*2C*/2C as a CYP1A1*2C carrier genotype, and GSTM3*A*B and GSTM3*B*B as a GSTM3*B carrier genotype.