Table 2.

Distribution of scoliosis characteristics and established breast cancer risk factors and risk of breast cancer among 3,010 participants of the U.S. Scoliosis Cohort Questionnaire Survey

CharacteristicsPerson-yearsn casesRelative risk (95% CI)*P for trendMean total breast dose (cGy)
Curve magnitude (°)
    <4019,91471.00.4211.8
    40-5922,289111.45 (0.56-3.79)14.8
    60-7912,57591.95 (0.71-5.31)16.0
    ≥808,01661.81 (0.60-5.49)18.8
    Unknown56,108451.28 (0.53-3.07)6.4
Total no. X-rays§
    Minimally exposed13,379141.35 (0.69-2.69)0.120
    1-932,178211.03.0
    10-1918,283151.62 (0.83-3.18)8.3
    20-3928,749101.97 (0.43-2.18)12.7
    40-5915,52781.66 (0.67-4.08)19.5
    ≥6010,785103.14 (1.33-7.44)33.5
Age at first live birth (y)
    <2551,665221.00.0310.6
    25-3431,339231.65 (0.91-2.98)9.2
    ≥353,61643.02 (1.03-8.87)10.9
    Nulliparous31,958292.13 (1.21-3.75)12.5
    Unknown324010.4
Parity
    Nulliparous31,958291.00.0612.5
    1-249,754230.56 (0.32-0.98)10.9
    3-428,888230.82 (0.47-1.43)9.0
    ≥58,06330.32 (0.10-1.05)9.0
    Unknown23908.6
Menopausal status**
    Premenopausal48,244101.00.00412.7
    Postmenopausal70,659683.13 (1.38-7.09)9.4
Highest completed education
    Elementary school11,51781.00.2910.9
    High school74,170481.16 (0.54-2.49)10.7
    College32,538211.47 (0.63-3.40)10.7
    Unknown70912.90 (0.28-18.2)11.8
Household income**
    <$30,00051,953311.00.00310.9
    $30,000-$59,99937,699181.13 (0.62-2.07)11.2
    ≥$ 60,00018,568182.84 (1.52-5.30)10.0
    Unknown10,684111.66 (0.83-3.32)9.8
Alcohol use**
    <1/wk70,862471.00.4210.5
    1-6/wk32,854170.93 (0.53-1.63)11.2
    1-3/d11,197121.65 (0.87-3.12)10.2
    ≥4/d1,56110.97 (0.13-7.04)13.8
    Unknown2,42810.63 (0.09-4.56)10.3
Smoking
    Never66,286511.00.07††11.1
    Past32,696200.77 (0.46-1.30)9.6
    Current19,72360.43 (0.19-1.00)11.4
    Unknown19214.94 (0.66-36.8)16.8
Family history of breast cancer
    None90,233471.00.00810.8
    Second-degree affected relatives only16,468192.71 (1.57-4.66)10.8
    Any first-degree affected relative12,203121.82 (0.96-3.44)10.1
No. relatives with breast cancer
    090,233471.00.000310.8
    1-227,551282.12 (1.32-3.41)10.5
    3-51,12035.65 (1.73-18.5)10.5
Family history early-onset breast cancer
    None115,618721.00.0310.8
    Any3,28662.84 (1.10-6.03)9.6
  • * Relative risk and 95% CI from separate models stratified by attained age (<35, 35-39, 40-44, 45-49, 50-54, 55-59, 60-69, and 70+ years) and calendar year (1925-1929, 1930-1934, …, 1990-1995) and adjusted for total number of X-rays (minimally exposed, <10, 10-19, 20-39, 40-59, and ≥60), where appropriate. The variable attained age was calculated in a time-dependent manner.

  • Excludes “unknown” category, where applicable.

  • Reference group.

  • § Refers to X-rays that involved the breast.

  • n = 245 women who had no recorded X-rays at the pediatric center where the spinal deformity was diagnosed.

  • Among parous women only.

  • ** At questionnaire completion.

  • †† Trend test contrasting ever and never smokers.

  • ‡‡ Diagnose <age 50.