title: Heterogeneity of epidemiological factors by breast tumor subtypes in Korean women: a case-case study.
abstract: Breast cancer is heterogeneous in clinical behavior by subtypes; however, it is unclear how this heterogeneity is related to epidemiological factors. To evaluate the differences in epidemiological factors by breast tumor subtypes, we investigated the associations of epidemiological factors between tumor subtypes in Korean women. From the Seoul Breast Cancer Study, a total of 3,058 patients with breast cancer were included in the analyses. Tumor subtypes were classified based on hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) statuses. The epidemiological factors of each subtype were compared through case-case analyses using multivariate a polytomous logistic regression model adjusted for age and recruiting centers. The distribution of the subtypes was as follows: 1,714 HR+ HER2- (56.0%), 414 HR+ HER2+ (13.5%), 423 HR- HER2+ (13.9%) and 507 HR- HER2- (16.6%) patients with breast cancer. There were significant differences in age, menopausal status, age at menarche, number of children, age at first full-term pregnancy (FFTP), duration of breastfeeding and duration of endogenous estrogen exposure between tumor subtypes (p < 0.05). Compared to HR+ HER2- patients, the other subtype patients showed more frequency in having more numbers of children and less frequency in having earlier menarche, later FFTP and longer endogenous estrogen exposure. Although HR- HER2+ patients were less obese, HR- HER2- patients were younger and more obese. In conclusion, age, body mass index and reproductive factors were differentially associated with breast tumor subtypes suggesting a possible distinct etiology for tumor progression.
authors.affiliation: Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Nan
authors.initials: N
authors.lastname: Song
authors.forename: Ji-Yeob
authors.initials: JY
authors.lastname: Choi
authors.forename: Hyuna
authors.initials: H
authors.lastname: Sung
authors.forename: Seokang
authors.initials: S
authors.lastname: Chung
authors.forename: Minkyo
authors.initials: M
authors.lastname: Song
authors.forename: Sue K
authors.initials: SK
authors.lastname: Park
authors.forename: Wonshik
authors.initials: W
authors.lastname: Han
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Mi Kyung
authors.initials: MK
authors.lastname: Kim
authors.forename: Keun-Young
authors.initials: KY
authors.lastname: Yoo
authors.forename: Sei-Hyun
authors.initials: SH
authors.lastname: Ahn
authors.forename: Dong-Young
authors.initials: DY
authors.lastname: Noh
authors.forename: Daehee
authors.initials: D
authors.lastname: Kang
mesh_terms: D000328:Adult; D000367:Age Factors; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D008572:Menarche; D008875:Middle Aged; D017720:Molecular Epidemiology; D009367:Neoplasm Staging; D010298:Parity; D011247:Pregnancy; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D017584:Reproductive History; D056910:Republic of Korea / Q000453:epidemiology
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human
keywords: breast cancer; case-case study; epidemiological factors; heterogeneity; tumor subtypes