Table 1.

Participants' characteristics in this study.

Cases, n (%)Controls, n (%)
N2871,083
Age at BBD biopsy
 <40 years76 (26.5)244 (22.5)
 40–49 years131 (45.6)431 (39.8)
 50–59 years56 (19.5)272 (25.1)
 ≥60 years24 (8.4)136 (12.6)
Year of BBD biopsy
 Before 197030 (10.4)55 (5.1)
 1970–197978 (27.2)224 (20.7)
 1980–1989128 (44.6)475 (43.9)
 After 198951 (17.8)329 (30.4)
Age at breast cancer diagnosis/index date
 <45 years41 (14.3)197 (18.2)
 45–54 years111 (38.7)361 (33.3)
 ≥55 years135 (47.0)525 (48.5)
Years between BBD biopsy and breast cancer diagnosis/index date
 0.5–4.9 years85 (29.6)501 (46.3)
 5.0–9.9 years101 (35.2)274 (25.3)
 10.0–14.9 years54 (18.8)169 (15.6)
 ≥15.0 years47 (16.4)139 (12.8)
BBD histologic subtype
 Nonproliferative59 (20.6)303 (28.0)
 Proliferative without atypia149 (51.9)625 (57.7)
 Atypical hyperplasia79 (27.5)155 (14.3)
  • Abbreviation: BBD, benign breast disease.