title: Longitudinal Change in Mammographic Density among ER-Positive Breast Cancer Patients Using Tamoxifen.
abstract: Tamoxifen-associated mammographic density (MD) reductions are linked to improved breast cancer survival. We evaluated MD at six time points to determine the timing of greatest reduction following tamoxifen initiation. We sampled 40 Kaiser Permanente Northwest estrogen receptor (ER)-positive breast cancer patients from a prior study of MD change, according to tamoxifen use duration and age at diagnosis: <4 years tamoxifen and ≤50 years (N = 6) or >50 years (N = 10) old; ≥4 years tamoxifen and ≤50 years (N = 13) or >50 years (N = 11) old. A single reader evaluated percent MD in the contralateral breast on baseline (pre-diagnosis) and five approximately yearly post-diagnostic (T1 to T5) mammograms. Mean MD change was calculated. Interactions with age (≤50 and >50 years), tamoxifen duration (<4 and ≥4 years), and baseline MD (tertiles) were tested in linear regression models. Overall, the largest MD decline occurred by T1 (mean 4.5%) with little additional decline by T5. Declines differed by tertile of baseline MD (Pinteraction < 0.01). In the highest tertile, the largest reduction occurred by T1 (mean 14.9%), with an additional reduction of 3.6% by T5. Changes were smaller in the middle and lowest baseline MD tertiles, with cumulative reductions of 3.0% and 0.4% from baseline to T5, respectively. There were no differences by age (Pinteraction = 0.36) or tamoxifen duration (Pinteraction = 0.42). Among ER-positive patients treated with tamoxifen and surviving ≥5 years, most of the MD reduction occurred within approximately 12 months of tamoxifen initiation, suggesting that MD measurement at a single time point following tamoxifen initiation can identify patients with substantial density declines.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland. sarah_nyante@med.unc.edu.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Nyante
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland. Division of Cancer Prevention, National Cancer Institute, Rockville, Maryland.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Sherman
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Pfeiffer
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.
authors.forename: Amy
authors.initials: A
authors.lastname: Berrington de Gonzalez
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.
authors.forename: Louise A
authors.initials: LA
authors.lastname: Brinton
authors.affiliation: Group Health Research Institute, Seattle, Washington.
authors.forename: Erin J Aiello
authors.initials: EJ
authors.lastname: Bowles
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Hoover
authors.affiliation: Kaiser Permanente Northwest Center for Health Research, Portland, Oregon.
authors.forename: Andrew
authors.initials: A
authors.lastname: Glass
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.
authors.forename: Gretchen L
authors.initials: GL
authors.lastname: Gierach
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage*; D000071060:Breast Density; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D042361:Mammary Glands, Human / Q000002:abnormalities* / Q000187:drug effects; D008327:Mammography; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011960:Receptors, Estrogen / Q000378:metabolism*; D013629:Tamoxifen / Q000008:administration & dosage*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D011960:Receptors, Estrogen; D013629:Tamoxifen