Table 1.

Characteristics of participants in the BCSC (1996–2012) and CBCS (1987–2007)

BCSCaCBCS
ControlsCases
N = 1,170,900 (Col %)N = 26,460 (Col %)N = 23,400 (Col %)
Age at enrollment
 40–49471,306 (40.3)5,381 (20.3)4,790 (20.5)
 50–59363,237 (31.0)8,663 (32.7)7,561 (32.3)
 60–74336,357 (28.7)12,416 (46.9)11,049 (47.2)
Year of report
 1987–1993NA (NA)13,035 (49.3)10,128 (43.3)
 1994–1999160,872 (13.7)7,505 (28.4)7,549 (32.3)
 2000–2004406,526 (34.7)4,451 (16.8)4,239 (18.1)
 2005–2009432,321 (36.9)1,469 (5.5)1,484 (6.3)
 2010–2013171,181 (14.6)NA (NA)NA (NA)
Benign breast biopsy
 No921,231 (78.7)21,485 (81.2)17,341 (74.1)
 Yes199,791 (17.1)4,319 (16.3)5,489 (23.5)
 Unknown49,878 (4.3)656 (2.5)570 (2.4)
Race/ethnicity
 Non-Hispanic White784,651 (67.0)25,617 (96.8)22,807 (97.5)
 Other223,743 (19.1)742 (2.8)522 (2.2)
 Unknown162,506 (13.9)101 (0.4)71 (0.3)
First-degree family history of breast cancer
 None1,025,508 (87.6)22,875 (86.5)18,479 (79.0)
 Any145,392 (12.4)3,585 (13.5)4,921 (21.0)
 1101,911 (8.7)3,284 (12.4)4,283 (18.3)
 >110,536 (0.9)301 (1.1)638 (2.7)
 Unspecifiedb32,945 (2.8)0 (0)0 (0)
  • Abbreviations: Col, column; NA, not available.

  • aOne randomly selected examination record per woman.

  • bUnknown number of affected family members (1 or more).