Table 1.

Selected characteristics of controls and cases

ControlsCases
Characteristicn = 882 (%)n = 985 (%)
Age (y)
 20–2924 (2.7)22 (2.2)
 30–3482 (9.3)77 (7.8)
 35–39249 (28.2)275 (27.9)
 40–44527 (59.8)611 (62.0)
Reference year
 2004–2005283 (32.1)283 (28.7)
 2006–2007338 (38.3)340 (34.5)
 2008–2010261 (29.6)362 (36.8)
Race/ethnicity
 Non-Hispanic White721 (82.1)785 (80.6)
 African-American27 (3.1)47 (4.8)
 Asian/Pacific Islander78 (8.9)103 (10.6)
 Other52 (5.9)39 (4.0)
 Missing411
Education
 High school or less89 (10.1)107 (10.9)
 Post high school/some college279 (31.7)321 (32.8)
 College graduate340 (38.7)363 (37.1)
 Post college171 (19.5)187 (19.1)
 Missing37
Annual household income
 <$25,00064 (7.3)67 (6.9)
 $25,000–49,999116 (13.3)152 (15.7)
 $50,000–89,999327 (37.4)310 (32.1)
 ≥$90,000368 (42.1)437 (45.2)
 Missing719
Age at menarche (y)
 <12178 (20.2)218 (22.2)
 12–13489 (55.6)558 (56.7)
 ≥14213 (24.2)208 (21.1)
 Missing21
Number of live births
 0185 (21.0)255 (25.9)
 1–2530 (60.1)570 (57.9)
 ≥3167 (18.9)159 (16.2)
 Missing01
Age at first live birth (y)
 <25196 (28.1)220 (30.2)
 25–29213 (30.6)246 (33.8)
 30–34194 (27.8)175 (24.0)
 ≥3594 (13.5)87 (12.0)
 Missing02
Lactation duration (mo)a
 None56 (8.1)70 (9.6)
 <6150 (21.6)169 (23.2)
 6–11135 (19.4)142 (19.5)
 ≥12354 (50.9)347 (47.7)
 Missing21
First-degree family history of breast cancer
 No765 (89.8)766 (80.3)
 Yes87 (10.2)188 (19.7)
 Missing3031
BMI 1 year before reference date (kg/m2)
 <25502 (57.2)588 (60.2)
 25–<30218 (24.9)228 (23.4)
 ≥30157 (17.9)160 (16.4)
 Missing59
Screening mammogram in prior 30 monthsb
 No189 (36.1)201 (32.9)
 Yes335 (63.9)410 (67.1)
 Missing30

Abbreviation: BMI, body mass index.

  • aAmong parous women.

  • bAmong women ages 40 to 44. Excludes symptomatic and diagnostic mammograms.