Table 2.

Use of adjuvant hormonal therapy and risk of second primary contralateral breast cancer by hormone receptor status

Use of adjuvant hormonal therapyControls (n = 727)Contralateral cases (n = 367)OR * (95% CI)
n (%)n (%)
All contralateral cases
    Never218 (30.0)144 (39.2)1.0 (Reference)
    Ever509 (70.0)223 (60.8)0.6 (0.5–0.8)
    <1 y99 (13.6)50 (13.6)0.7 (0.5–1.1)
    1–4 y276 (40.0)118 (32.2)0.6 (0.4–0.8)
    ≥5 y134 (18.4)55 (15.0)0.5 (0.3–0.8)
ER+ contralateral cases
    Never182 (30.5)132 (43.6)1.0 (Reference)
    Ever415 (69.5)171 (56.4)0.5 (0.4–0.7)
    <1 y71 (12.7)39 (12.9)0.7 (0.4–1.1)
    1–4 y216 (38.7)94 (31.0)0.5 (0.4–0.7)
    ≥5 y104 (18.6)38 (12.5)0.4 (0.2–0.6)
ER+/PR+ contralateral cases
    Never151 (33.1)111 (47.8)1.0 (Reference)
    Ever305 (66.9)121 (52.2)0.5 (0.3–0.7)
    <1 y56 (12.3)33 (14.2)0.8 (0.4–1.3)
    1–4 y174 (38.2)62 (26.7)0.4 (0.3–0.7)
    ≥5 y74 (16.3)26 (11.2)0.4 (0.2–0.7)
ER− contralateral cases
    Never29 (27.1)10 (19.2)1.0 (Reference)
    Ever78 (72.9)42 (80.8)1.3 (0.6–3.0)
    <1 y16 (15.0)9 (17.3)1.3 (0.4–4.3)
    1–4 y43 (40.2)17 (32.7)1.0 (0.4–2.4)
    ≥5 y19 (17.8)16 (30.8)3.8 (0.98–14.6)
ER−/PR− contralateral cases
    Never27 (29.7)9 (20.0)1.0 (Reference)
    Ever64 (10.3)36 (80.0)1.4 (0.6–3.3)
    <1 y14 (15.4)7 (15.6)1.0 (0.3–3.6)
    1–4 y37 (40.7)16 (35.6)1.1 (0.4–3.0)
    ≥5 y13 (14.3)13 (28.9)4.9 (1.1–22.5)
  • NOTE: The 12 cases with missing ER status and their matched 23 matched controls were excluded from the ER-specific analyses, and the 90 cases with other/missing ER/PR status and their matched 180 matched controls were excluded from the ER/PR-specific analyses.

  • * ORs and 95% CIs were estimated using conditional logistic regression and are adjusted for radiation therapy.