Table 4

ORs for smoking and breast cancer, stratified by GSTM1, GSTT1, and GSTP1 genotypes

GSTM1 Null ORa (95% CI)GSTM1 Present OR (95% CI)GSTT1 Null OR (95% CI)GSTT1 Present OR (95% CI)GSTP1 Ile/Val and Val/Val OR (95% CI)GSTP1 Ile/Ile OR (95% CI)
Active smoking status
NeverReferentReferentReferentReferentReferentReferent
Current1.2 (0.7–1.9)0.7 (0.4–1.0)0.3 (0.1–0.9)0.9 (0.6–1.3)0.8 (0.6–1.3)0.7 (0.4–1.2)
Former1.2 (0.7–1.8)1.4 (0.9–2.0)1.5 (0.7–3.0)1.2 (0.9–1.7)1.1 (0.8–1.5)1.7 (1.0–2.7)
Usual amount smoked (packs/day)
NeverReferentReferentReferentReferentReferentReferent
<1/21.2 (0.7–2.1)1.0 (0.6–1.5)0.7 (0.3–1.7)1.1 (0.8–1.6)0.9 (0.6–1.3)1.1 (0.6–2.0)
1/2–11.4 (0.8–2.4)1.1 (0.7–1.7)0.8 (0.3–1.9)1.2 (0.9–1.8)1.0 (0.7–1.6)1.7 (0.9–3.2)
>10.9 (0.5–1.6)1.1 (0.6–1.8)1.9 (0.7–5.5)0.9 (0.6–1.3)1.0 (0.6–1.7)0.7 (0.4–1.3)
Trend testP = 0.8P = 0.8P = 0.5P = 0.8P = 0.9P = 0.9
Duration of smoking (years)
≤101.0 (0.6–1.8)1.0 (0.6–1.5)0.8 (0.3–2.3)1.0 (0.7–1.5)0.7 (0.4–1.1)1.3 (0.6–2.6)
11–200.7 (0.4–1.3)1.0 (0.6–1.6)1.0 (0.4–2.6)0.8 (0.5–1.2)0.9 (0.5–1.5)0.8 (0.4–1.4)
>201.7 (1.0–2.8)1.1 (0.7–1.7)0.9 (0.4–2.2)1.3 (0.9–1.8)1.3 (0.9–2.0)1.4 (0.8–2.3)
Trend testP = 0.1P = 0.7P = 0.9P = 0.3P = 0.3P = 0.5
Former smokers: time since cessation (yr)
≤31.7 (0.8–3.6)2.3 (1.2–4.5)2.2 (0.7–7.1)2.0 (1.1–3.5)1.6 (0.9–3.1)3.3 (1.2–8.8)
4–190.9 (0.5–1.6)1.3 (0.8–2.1)1.4 (0.5–3.9)1.1 (0.7–1.6)1.0 (0.6–1.5)1.6 (0.8–3.1)
>201.4 (0.7–3.0)0.8 (0.5–1.6)1.3 (0.4–3.8)1.1 (0.6–1.8)0.9 (0.5–1.6)1.2 (0.6–2.7)
Trend testP = 0.6P = 0.7P = 0.5P = 0.6P = 0.8P = 0.2
Never active smokers
Unexposed to active or ETSReferentReferentReferentReferentReferentReferent
Exposed to ETS after age 180.8 (0.4–1.4)1.3 (0.8–2.0)1.9 (0.7–5.4)1.0 (0.7–1.5)1.0 (0.6–1.5)1.1 (0.6–2.1)
  • a Adjusted for age, race, menopausal status, age at first full-term pregnancy/parity composite, breastfeeding, family history of breast cancer, biopsy, and alcohol consumption.