Table 2.

Adjusted ORs and 95% CI for alcohol, smoking, and physical activity associated with breast cancer subtypes

Luminal A–likeLuminal B–like HER2 negativeLuminal B–like HER2 positiveHER2 positiveTriple negative
ER+PR+HER2ER+PRHER2ER+PR+/PRHER2+ERPRHER2+ERPRHER2
ca/coORa (95% CI)ca/coOR (95% CI)ca/coOR (95% CI)ca/coOR (95% CI)ca/coOR (95% CI)
Alcohol intake per week, currentb
 0–1 glass1025/55431 (Ref)262/14111 (Ref)138/7501 (Ref)93/3881 (Ref)142/7361 (Ref)
 2 glasses530/27401.03 (0.92–1.16)155/6771.24 (0.99–1.56)66/3411.06 (0.76–1.48)37/1960.81 (0.52–1.25)62/3750.87 (0.62–1.21)
 3+ glasses1206/55221.14 (1.04–1.26)292/14571.05 (0.87–1.28)163/7441.23 (0.94–1.62)74/4360.68 (0.47–0.97)157/6941.20 (0.93–1.57)
Ptrenda0.010.460.140.030.24
Pheterogeneityc0.020.220.140.23
Smokingd
 Never1,081/5,8771 (Ref)273/1,4641 (Ref)154/7921 (Ref)93/4371 (Ref)147/7351 (Ref)
 Past1,014/4,7941.12 (1.01–1.23)248/1,2541.06 (0.87–1.29)119/6350.88 (0.67–1.15)67/3311.01 (0.70–1.47)131/6151.01 (0.77–1.33)
 Current666/3,1341.18 (1.05–1.32)188/8271.22 (0.98–1.52)94/4081.15 (0.85–1.56)44/2520.86 (0.56–1.30)83/4550.88 (0.64–1.20)
Ptrend0.0030.080.500.510.46
Pheterogeneity0.050.130.310.95
Number of cigarettes per day, currentd
 Never1,081/5,8771 (Ref)273/1,4641.00 (Ref)154/7921 (Ref)93/4371 (Ref)147/7351 (Ref)
 1–4170/7741.18 (0.97–1.43)41/2171.03 (0.70–1.52)26/951.36 (0.81–2.27)10/570.93 (0.39–2.19)15/1160.63 (0.34–1.15)
 5–9225/1,2041.09 (0.91–1.29)68/3311.27 (0.91–1.77)31/1611.00 (0.62–1.62)16/980.96 (0.49–1.88)33/1590.93 (0.58–1.49)
 10+281/1,2201.27 (1.07–1.50)83/3141.38 (1.00–1.89)37/1651.00 (0.63–1.58)20/960.94 (0.50–1.77)42/1851.14 (0.74–1.76)
Ptrend0.010.030.950.830.69
Pheterogeneity0.340.480.220.91
Pack-years of smokingd
 <2.5905/5,0871 (Ref)226/1,2711.00 (Ref)1241 (Ref)80/3661 (Ref)126/6531 (Ref)
 2.5–4.991/4261.17 (0.90–1.52)27/1041.75 (1.04–2.94)111.28 (0.60–2.75)10/341.80 (0.73–4.42)12/491.20 (0.56–2.56)
 5.0–9.9169/7591.26 (1.03–1.55)31/1890.90 (0.56–1.44)120.63 (0.32–1.27)10/531.05 (0.47–2.35)30/921.51 (0.88–2.60)
 10.0–14.9156/7111.22 (0.99–1.51)42/1801.28 (0.84–1.96)291.60 (0.93–2.77)13/501.18 (0.54–2.59)18/960.94 (0.51–1.73)
 15–19.9108/5271.04 (0.82–1.33)27/1371.19 (0.71–2.01)120.76 (0.36–1.58)7/361.15 (0.43–3.06)8/750.44 (0.19–1.02)
 ≥20202/8571.27 (1.04–1.54)57/2051.62 (1.09–2.40)220.93 (0.52–1.69)15/581.09 (0.53–2.26)29/1371.19 (0.71–2.02)
Ptrend0.010.030.960.760.93
Pheterogeneity0.790.730.240.44
Low- and high-intensity physical activity per week, currente
 0–1 hours450/2,0401 (Ref)110/5241 (Ref)59/3141 (Ref)37/1431 (Ref)50/2741 (Ref)
 2–3 hours1,298/6,2970.94 (0.84–1.06)322/1,6350.93 (0.73–1.18)183/7831.35 (0.97–1.89)89/4630.68 (0.43–1.05)163/8181.08 (0.77–1.53)
 4+ hours1,009/5,4410.85 (0.75–0.97)275/1,3780.92 (0.72–1.18)125/7351.02 (0.72–1.45)78/4130.67 (0.42–1.06)148/7111.14 (0.80–1.64)
Ptrend0.010.540.980.100.46
Pheterogeneity0.080.550.580.60
  • Abbreviations: ca, case; co, controls.

  • aPtrend and OR mutual adjusted BMI (≤22, 23–25, 26–28, >28 at screening), education (no education/primary school, high school, bachelor, and master), age at menarche (9–12, 13, 14, 15–18), number of pregnancies (never, 1, 2, 3, ≥4), and menopausal status (pre-, peri-, postmenopausal).

  • bAlcohol additionally adjusted for physical activity (never, 1 hour, 2–3 hours, 4–5 hours, 6+ hours) and smoking (never, past, and current).

  • cPheterogeneity across subtypes was determined in a case–case model. See Materials and Methods for details.

  • dSmoking additionally adjusted for alcohol (never drinkers, 1 glass, 2 glasses, 3–4 glasses, 5+ glasses) and physical activity (never, 1 hour, 2–3 hours, 4–5 hours, 6+ hours).

  • ePhysical activity additionally adjusted for alcohol (never drinkers, 1 glass, 2 glasses,3–4 glasses, 5+ glasses) and smoking (never, past, and current).