Table 4.

Invasive breast cancer HRs and 95% CIs, by menopausal status, associated with any exposure and intensity-years of passive smoke exposure in the CTS

Menopausal status*nNo. casesHR (95% CI)HR (95% CI)
Adjusted for age and raceAdjusted for age, race, and personal risk factors
Premenopausal at baseline
    Any exposure
        Lifetime exposure
            Never4,030591.001.00
            Ever21,5104041.04 (0.79-1.38)1.04 (0.79-1.38)
        Age-specific exposure
            Never4,030591.001.00
            Ever exposed <age 2017,6363240.96 (0.77-1.18)0.95 (0.77-1.18)
            Ever exposed ≥age 2016,2593070.96 (0.77-1.19)0.95 (0.77-1.19)
    Intensity-years
        Lifetime exposure
            None4,030591.001.00
            Low (≤17.5)9,6861761.11 (0.83-1.50)1.11 (0.82-1.49)
            Medium (17.6-42.0)6,5871301.06 (0.77-1.44)1.06 (0.77-1.44)
            High (>42.0)4,808900.92 (0.66-1.28)0.92 (0.66-1.29)
        Age-specific exposure
            None4,030591.001.00
            Age <20 exposure
                Low (≤17.5)10,3901860.97 (0.77-1.22)0.96 (0.76-1.21)
                Medium (17.6-42.0)4,788951.02 (0.77-1.34)1.02 (0.78-1.36)
                High (>42.0)2,019310.77 (0.51-1.16)0.77 (0.51-1.16)
            Age ≥20 exposure
                Low (≤17.5)11,5282080.98 (0.78-1.23)0.97 (0.77-1.22)
                Medium (17.6-42.0)2,975620.96 (0.69-1.32)0.95 (0.69-1.31)
                High (>42.0)1,257300.98 (0.64-1.50)0.98 (0.64-1.51)
Premenopausal at baseline and age <50 at follow-up
    Any exposure
        Lifetime exposure
            Never2,235321.001.00
            Ever7,8431600.89 (0.60-1.33)0.93 (0.61-1.41)
        Age-specific exposure
            Never2,235321.001.00
            Ever exposed <age 206,5501290.93 (0.65-1.31)1.02 (0.71-1.48)
            Ever exposed ≥age 205,3661190.94 (0.66-1.32)0.90 (0.63-1.29)
    Intensity-years
        Lifetime exposure
            None2,235321.001.00
            Low (≤17.5)4,313790.90 (0.58-1.40)0.91 (0.58-1.43)
            Medium (17.6-42.0)2,226440.75 (0.46-1.22)0.80 (0.48-1.34)
            High (>42.0)1,190331.13 (0.68-1.89)1.20 (0.70-2.05)
        Age-specific exposure
            None2,235321.001.00
            Age <20 exposure
                Low (≤17.5)4,109690.82 (0.55-1.21)0.87 (0.57-1.31)
                Medium (17.6-42.0)1,656401.07 (0.67-1.70)1.20 (0.74-1.95)
                High (>42.0)649141.10 (0.57-2.13)1.15 (0.58-2.28)
            Age ≥20 exposure
                Low (≤17.5)4,501900.87 (0.61-1.25)0.80 (0.55-1.17)
                Medium (17.6-42.0)660181.00 (0.55-1.81)1.12 (0.60-2.07)
                High (>42.0)8961.15 (0.43-3.05)0.98 (0.34-2.79)
Postmenopausal at baseline
    Any exposure
        Lifetime exposure
            Never2,545841.001.00
            Ever23,0029891.25 (1.00-1.57)1.22 (0.97-1.52)
        Age-specific exposure
            Never2,545841.001.00
            Ever exposed <age 2015,8576881.12 (0.96-1.30)1.12 (0.97-1.31)
            Ever exposed ≥age 2020,7749101.15 (0.95-1.39)1.11 (0.92-1.34)
    Intensity-years
        Lifetime exposure
            None2,545841.001.00
            Low (≤17.5)6,2812511.19 (0.93-1.52)1.17 (0.91-1.49)
            Medium (17.6-42.0)6,2702641.23 (0.96-1.57)1.19 (0.93-1.53)
            High (>42.0)9,3934301.31 (1.03-1.65)1.26 (0.99-1.60)
        Age-specific exposure
            None2,545841.001.00
            Age <20 exposure
                Low (≤17.5)8,9004111.16 (0.99-1.37)1.17 (0.99-1.37)
                Medium (17.6-42.0)4,1681610.95 (0.77-1.16)0.96 (0.78-1.18)
                High (>42.0)1,654771.13 (0.86-1.48)1.14 (0.87-1.50)
            Age ≥20 exposure
                Low (≤17.5)7,7683251.15 (0.93-1.41)1.12 (0.91-1.37)
                Medium (17.6-42.0)5,2112051.06 (0.84-1.32)1.02 (0.81-1.28)
                High (>42.0)6,5633271.31 (1.05-1.62)1.25 (1.01-1.56)
  • *There were too few cases in the perimenopausal group at baseline to include in these analyses.

  • Personal risk factors include family history of breast cancer, age at menarche, pregnancy history, lifetime duration of breast-feeding, BMI, physical activity, alcohol consumption, and use of hormone therapy.

  • Premenopausal at baseline and follow-up includes women who were premenopausal at baseline and either diagnosed or censored before the age of 50.