title: Adjuvant hormonal therapy for breast cancer and risk of hormone receptor-specific subtypes of contralateral breast cancer.
abstract: Compared with the breast cancer risk women in the general population have, breast cancer survivors have a substantially higher risk of developing a second primary contralateral breast cancer. Adjuvant hormonal therapy reduces this risk, but preliminary data indicate that it may also increase risk of hormone receptor-negative contralateral tumors. We conducted a population-based nested case-control study including 367 women diagnosed with both first primary estrogen receptor (ER)-positive invasive breast cancer and second primary contralateral breast cancer and 728 matched control women diagnosed only with a first breast cancer. Data on adjuvant hormonal therapy, other treatments, and breast cancer risk factors were ascertained through telephone interviews and medical record abstractions. Two-sided statistical tests using conditional logistic regression were conducted to quantify associations between adjuvant hormonal therapy and risk of hormone receptor-specific subtypes of contralateral breast cancer (n = 303 ER+ and n = 52 ER- cases). Compared with women not treated with hormonal therapy, users of adjuvant tamoxifen for >or=5 years had a reduced risk of ER+ contralateral breast cancer [odds ratio, 0.4; 95% confidence interval (CI), 0.3-0.7], but a 4.4-fold (95% CI, 1.03-19.0) increased risk of ER- contralateral breast cancer. Tamoxifen use for <5 years was not associated with ER- contralateral breast cancer risk. Although adjuvant hormonal therapy has clear benefits, risk of the relatively uncommon outcome of ER- contralateral breast cancer may now need to be tallied among its risks. This is of clinical concern given the poorer prognosis of ER- compared with ER+ tumors.
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA. cili@fhcrc.org
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Li
authors.forename: Janet R
authors.initials: JR
authors.lastname: Daling
authors.forename: Peggy L
authors.initials: PL
authors.lastname: Porter
authors.forename: Mei-Tzu C
authors.initials: MT
authors.lastname: Tang
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Malone
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D016022:Case-Control Studies; D017024:Chemotherapy, Adjuvant; D005260:Female; D006801:Humans; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000188:drug therapy*; D011960:Receptors, Estrogen / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000008:administration & dosage / Q000009:adverse effects; D013629:Tamoxifen / Q000008:administration & dosage* / Q000009:adverse effects; D016896:Treatment Outcome
chemical_list: D018931:Antineoplastic Agents, Hormonal; D011960:Receptors, Estrogen; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen
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