BMC Cancer 2008, 8:157 http://www.biomedcentral.com/1471-2407/8/157 Table 1: Selected characteristics of breast cancer cases and controls, Delaware, 2000–2002 cases (n = 287) controls (n = 311) Characteristic Age at interview (years) 40–49 50–59 60–69 70–80 Race White Black/Other Educationb <12 grades 12 grades some college post-college Menopausal status premenopausal postmenopausal Body mass index (kg/m2)b 15–24 25–29 30–88 Age at menarche (years)b 8–12 13–18 Number of Live Birthsb nulliparousc 1–2 3–4 5–11 Age at 1st live birth (years)b < 30 30+ Oral contraceptive use Never Ever Other hormone useb Never Ever Family History of Breast Cancerb,c No Yes Alcohol consumption < 12 drinks in lifetime ≥ 12 drinks in lifetime, but never had ≥ 1 drink per mo. for ≥ 6 mos drank ≥ 1 drink per mo. for ≥ 6 mos n 53 74 87 73 264 23 30 114 108 34 30 257 107 102 78 140 144 44 128 97 18 219 24 120 167 153 134 220 63 37 87 163 % 18.5 25.8 30.3 25.4 92.0 8.1 10.5 39.9 37.8 11.9 10.5 89.6 37.3 35.5 27.2 49.3 50.7 15.3 44.6 33.8 6.3 90.1 9.9 41.8 58.2 53.3 46.7 77.7 22.3 12.9 30.3 56.8 n 63 94 77 77 294 17 14 108 148 41 65 246 122 114 72 142 168 35 145 112 18 242 33 110 201 161 149 257 53 49 85 177 % 20.3 30.2 24.8 24.7 94.5 5.5 4.5 37.8 47.6 13.2 20.9 79.1 39.6 37.0 23.4 45.8 54.2 11.3 46.8 36.1 5.8 88.0 12.0 35.4 64.6 51.9 48.1 82.9 17.1 15.8 27.3 56.9 p-valuea 0.32 0.21 < 0.01 < 0.01 0.56 0.39 0.52 0.44 0.11 0.74 0.11 0.52 a p-values based on chi-square test; p-values based on Mantel-Haenszel chi-square test for trend for the following variables: age, education, BMI, and age at first live birth b Numbers do not always sum to total number of cases and/or controls due to missing information c Includes 9 cases and 10 controls who reported 1+ pregnancies d Family history of breast cancer defined as mother or sister ever diagnosed with breast cancer years (see additional file 1). Weighting pack-years by the number of hours exposed to secondhand tobacco smoke each day did not result in any considerable differences in breast cancer risks (see additional file 1). Similarly, sec- ondhand smoke exposure in the home during adulthood was not associated with breast cancer risk, regardless of the exposure metric used (OR = 0.98, 95% CI = 0.58– 1.64). Combining childhood and adulthood exposures, no increased risks were observed with 45 or more pack- years of lifetime residential secondhand smoke. Second- Page 4 of 9 (page number not for citation purposes)