Table 1.

Distribution of selected characteristics of breast cancer patients according to OC use status in the Women's CARE Study and the CTS

Women's CARE study (N = 4,565) OC useCTS (age 35–64; N = 2,222) OC useCTS (all; N = 3,929) OC use
Never (N = 1,041)Ever (N = 3,524)Never (N = 395)Ever (N = 1,827)Never (N = 1,490)Ever (N = 2,439)
Age at diagnosis, y
 <350.10.3
 35–397.617.31.32.60.31.9
 40–448.419.05.83.81.52.8
 45–498.719.610.911.22.98.4
 50–5415.019.519.522.85.217.1
 55–5922.915.024.332.36.424.2
 60–6437.69.638.227.410.120.5
 >6473.424.8
Race
 White62.865.083.088.988.489.4
 Black (CARE)/other (CTS)37.235.017.011.111.610.6
Family history of breast cancer (first degree)
 No77.679.476.480.079.779.3
 Yes17.416.919.817.217.017.9
Adopt/unknown5.03.73.82.83.32.8
Body mass index (BMI)a, kg/m2
 <208.311.49.49.77.18.7
 20–24.937.647.744.650.543.449.6
 25–29.927.825.730.423.830.724.8
 ≥3025.814.712.913.713.414.0
 Unknown0.60.62.82.45.52.9
Menopausal status
 Premenopausal24.352.838.041.310.331.2
 Postmenopausal68.134.353.941.287.555.3
 Unknown7.612.98.117.62.213.5
Stage
 Localized62.759.667.164.470.866.7
 Nonlocalized37.340.432.935.629.233.3
Estrogen status
 Positive64.757.073.772.573.672.8
 Negative21.330.812.914.711.414.2
 Unknown14.012.213.412.815.013.0
Study site
 Atlanta19.319.3
 Seattle18.424.8
 Detroit15.314.7
 Philadelphia20.913.8
 Los Angeles26.127.5
Education
 Not a high school graduate16.36.5
 High school graduate34.927.5
 Some college or technical school26.434.2
 College graduate22.331.8
Socioeconomic status
 Lowest quartile3.83.24.53.3
 Second quartile13.914.716.314.4
 Third quartile28.630.830.530.5
 Highest quartile52.950.447.650.7
 Unknown0.81.01.11.1

Abbreviations: CARE, Contraceptive and Reproductive Experiences; CTS, California Teachers Study; OC, oral contraceptives.

  • aBMI: at 5 years before breast cancer diagnosis for the CARE Study and at cohort entry for the CTS.