title: Prognostic implications of estrogen receptor pattern of both tumors in contralateral breast cancer.
abstract: Estrogen receptor (ER) status is important for breast cancer survival, it is however unclear how prognosis of contralateral breast cancer (CBC) is affected by ER-status of the two tumors. We conducted a large, population-based study of ER-status of both tumors in CBC patients and its influence on prognosis. The cohort consisted of all women diagnosed with CBC in Stockholm, Sweden during 1976-2005, with information on ER-status from medical records (N = 933). Prognosis was modeled as incidence rates of distant metastasis via Poisson regression. The proportion of CBCs with both cancers of the same ER-status was significantly larger than expected by chance. For synchronous (simultaneous) cancers the prognosis was significantly affected by the combined ER-status of both tumors (p = 0.01). Compared to unilateral breast cancer patients the incidence rate ratio (IRR) for patients with double ER-positive tumors was 1.25 (95 % CI: 0.88-1.76), for ER-discordant tumors 2.19 (95 % CI: 1.18-4.08) and for double ER-negative tumors 3.95 (95 % CI: 1.77-8.81). For metachronous (non-simultaneous) cancers, women with double ER-positive tumors had similarly bad prognosis (IRR = 2.95; 95 % CI: 2.39-3.64) as women with double ER-negative tumors (IRR = 2.88; 95 % CI: 1.83-4.52). Both shorter time span between first and second cancer and endocrine therapy for the first cancer further worsened prognosis of women with double ER-positive metachronous CBC. For synchronous CBC patients, ER-pattern of both tumors is an important prognosticator, while among metachronous CBC patients, double ER-positive tumors confer equally bad prognosis as double ER-negative cancers. Our results indicate that this might be due to endocrine therapy resistance.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden. maria.sandberg@ki.se
authors.forename: Maria E C
authors.initials: ME
authors.lastname: Sandberg
authors.forename: Mikael
authors.initials: M
authors.lastname: Hartman
authors.forename: Daniel
authors.initials: D
authors.lastname: Klevebring
authors.forename: Sandra
authors.initials: S
authors.lastname: Eloranta
authors.forename: Alexander
authors.initials: A
authors.lastname: Ploner
authors.forename: Per
authors.initials: P
authors.lastname: Hall
authors.forename: Kamila
authors.initials: K
authors.lastname: Czene
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology / Q000378:metabolism* / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009378:Neoplasms, Multiple Primary / Q000453:epidemiology / Q000378:metabolism* / Q000473:pathology; D016609:Neoplasms, Second Primary / Q000453:epidemiology / Q000378:metabolism* / Q000473:pathology; D016012:Poisson Distribution; D011379:Prognosis; D011960:Receptors, Estrogen / Q000378:metabolism*; D012044:Regression Analysis
chemical_list: D011960:Receptors, Estrogen