Table 5.

Associations between polymorphisms in MGMT, XPD, and XPG and risk of colorectal polyps stratified by smoking

Diagnostic groupEnzymeGenotypeSmoking (pack-years)
Pinteraction (smoking × genotype)
0
1-25
>25
CasesControlsOR* (95% CI)CasesControlsOR* (95% CI)CasesControlsOR* (95% CI)
Adenomatous polyps onlyMGMTHomozygous wt921751.00 (Reference)74971.48 (0.97-2.27)77781.50 (0.97-2.33)
Heterozygous41980.79 (0.49-1.28)43651.24 (0.75-2.04)29341.14 (0.62-2.08)
Homozygous variant13241.08 (0.50-2.33)3200.30 (0.08-1.07)1291.84 (0.67-5.07)0.20
XPDHomozygous wt37941.00 (Reference)35461.70 (0.90-3.19)33421.45 (0.76-2.75)
Heterozygous771561.17 (0.71-1.93)56931.60 (0.94-2.74)62671.70 (0.98-2.96)
Homozygous variant32461.83 (0.96-3.47)29431.60 (0.83-3.09)23123.93 (1.68-9.21)0.42
XPGHomozygous wt871661.00 (Reference)741081.28 (0.83-1.95)78721.59 (1.01-2.50)
Heterozygous491160.82 (0.52-1.29)40611.36 (0.81-2.28)34441.17 (0.67-2.05)
Homozygous variant10161.20 (0.49-2.92)6130.91 (0.32-2.58)651.46 (0.41-5.15)0.79
Hyperplastic polyps onlyMGMTHomozygous wt281751.00 (Reference)50973.04 (1.76-5.25)33782.32 (1.28-4.21)
Heterozygous15981.03 (0.52-2.05)19651.77 (0.89-3.51)37346.23 (3.25-11.97)
Homozygous variant1240.30 (0.04-2.31)3200.93 (0.25-3.39)392.27 (0.55-9.37)0.02
XPDHomozygous wt20941.00 (Reference)16461.56 (0.72-3.38)20421.77 (0.83-3.76)
Heterozygous161560.46 (0.22-0.95)40931.85 (0.99-3.48)39672.44 (1.27-4.69)
Homozygous variant9460.99 (0.41-2.37)16431.59 (0.73-3.48)14125.09 (1.96-13.25)0.09
XPGHomozygous wt301661.00 (Reference)401081.84 (1.06-3.19)48723.09 (1.76-5.43)
Heterozygous141160.61 (0.30-1.23)30612.54 (1.38-4.59)23442.64 (1.36-5.13)
Homozygous variant0163131.03 (0.27-3.92)351.38 (0.25-7.65)0.54
Adenomatous + hyperplastic polypsMGMTHomozygous wt151751.00 (Reference)27973.83 (1.79-8.16)28783.22 (1.50-6.89)
Heterozygous8981.19 (0.45-3.09)8651.72 (0.65-4.61)17344.19 (1.74-10.13)
Homozygous variant5243.86 (1.17-12.71)3202.26 (0.55-9.24)898.06 (2.30-28.18)0.16
XPDHomozygous wt8941.00 (Reference)11462.65 (0.90-7.80)24424.74 (1.77-12.72)
Heterozygous111561.02 (0.36-2.82)24933.79 (1.48-9.71)23672.76 (1.06-7.34)
Homozygous variant9462.62 (0.83-8.27)3430.90 (0.20-3.97)6125.52 (1.46-20.86)0.04
XPGHomozygous wt141661.00 (Reference)251082.78 (1.29-5.96)31723.32 (1.53-7.19)
Heterozygous101161.06 (0.42-2.66)13613.11 (1.28-7.57)19443.88 (1.68-8.96)
Homozygous variant4163.34 (0.88-12.71)013353.73 (0.76-18.35)0.86
  • * Multivariate adjusted for age, sex, BMI, kcal, alcohol intake, dietary fiber, regular NSAIDs use, and hormone replacement therapy.

  • Heterozygotes: L-I/F-I and L-I/L-V; homozygous variants: F-I/F-I, F-I/L-V or L-I/F-V, F-I/FV, L-V/L-V, L-V/F-V, and F-V/F-V.

  • Heterozygotes: D-K/N-K, D-K/D-Q, D-K/N-Q, or N-K/D-Q; homozygous variant: N-K/N-K, N-K/N-Q, D-Q/D-Q, D-Q/N-Q, and N-Q/N-Q.