Reproductive profiles and risk of breast cancer subtypes: a multi-center case-only study.
Creators: name: Brouckaert, Olivier
name: Rudolph, Anja
name: Laenen, Annouschka
name: Keeman, Renske
name: Bolla, Manjeet K
name: Wang, Jean
name: Soubry, Adelheid
name: Wildiers, Hans
name: Andrulis, Irene L
name: Arndt, Volker
name: Beckmann, Matthias W
name: Benitez, Javier
name: Blomqvist, Carl
name: Bojesen, Stig E
name: Brauch, Hiltrud
name: Brennan, Paul
name: Brenner, Hermann
name: Chenevix-Trench, Georgia
name: Choi, Ji-Yeob
name: Cornelissen, Sten
name: Couch, Fergus J
name: Cox, Angela
name: Cross, Simon S
name: Czene, Kamila
name: Eriksson, Mikael
name: Fasching, Peter A
name: Figueroa, Jonine
name: Flyger, Henrik
name: Giles, Graham G
name: González-Neira, Anna
name: Guénel, Pascal
name: Hall, Per
name: Hollestelle, Antoinette
name: Hopper, John L
name: Ito, Hidemi
name: Jones, Michael
name: Kang, Daehee
name: KConFab, 
name: Knight, Julia A
name: Kosma, Veli-Matti
name: Li, Jingmei
name: Lindblom, Annika
name: Lilyquist, Jenna
name: Lophatananon, Artitaya
name: Mannermaa, Arto
name: Manoukian, Siranoush
name: Margolin, Sara
name: Matsuo, Keitaro
name: Muir, Kenneth
name: Nevanlinna, Heli
name: Peterlongo, Paolo
name: Pylkäs, Katri
name: Saajrang, Suleeporn
name: Seynaeve, Caroline
name: Shen, Chen-Yang
name: Shu, Xiao-Ou
name: Southey, Melissa C
name: Swerdlow, Anthony
name: Teo, Soo-Hwang
name: Tollenaar, Rob AEM
name: Truong, Thérèse
name: Tseng, Chiu-Chen
name: Van Den Broek, Alexandra J
name: Van Deurzen, Carolien HM
name: Winqvist, Robert
name: Wu, Anna H
name: Yip, Cheng Har
name: Yu, Jyh-Cherng
name: Zheng, Wei
name: Milne, Roger L
name: Pharoah, Paul
name: Easton, Douglas
name: Schmidt, Marjanka K
name: Garcia-Closas, Montserrat
name: Chang-Claude, Jenny
name: Lambrechts, Diether
name: Neven, Patrick
Publisher: name: Apollo - University of Cambridge Repository
Year: 2017
Subjects: kConFab
Humans
Breast Neoplasms
Reproductive History
Odds Ratio
Risk Assessment
Risk Factors
Cohort Studies
Adult
Aged
Middle Aged
Female
Young Adult
Triple Negative Breast Neoplasms
Biomarkers, Tumor

description: Background: Previous studies have shown that reproductive factors are differentially associated with breast cancer (BC) risk by subtypes. The aim of this study was to investigate associations between reproductive factors and BC subtypes, and whether these vary by age at diagnosis. Methods: We used pooled data on tumor markers (estrogen and progesterone receptor, human epidermal growth factor receptor-2 (HER2)) and reproductive risk factors (parity, age at first full-time pregnancy (FFTP) and age at menarche) from 28095 invasive BC patients from 34 studies participating in the Breast Cancer Association Consortium (BCAC). In a case-only analysis, we used logistic regression to assess associations between reproductive factors and BC subtype compared to luminal A tumors as a reference. The interaction between age and parity on BC subtype risk was also tested, across all ages and, because age was modeled nonlinearly, specifically at age 35, 55 and 75. Results: Parous women were more likely to be diagnosed with triple negative BC (TNBC) than with luminal A BC, irrespective of age (OR for parity=1.38, 95%CI 1.16-1.65, P=0.0004; Pinteraction with age=0.076). Parous women were also more likely to be diagnosed with luminal and non-luminal HER2-like BCs and this effect was slightly more pronounced at an early age (P-interaction with age=0.037 and 0.030, respectively). For instance, women diagnosed at age 35 were 1.48 (CI 1.01-2.16) more likely to have luminal HER2-like BC than luminal A BC, while this association was not significant at age 75 (OR=0.72, CI 0.45-1.14). While age at menarche was not significantly associated with BC subtype, increasing age at FFTP was non-linearly associated with TNBC relative to luminal A BC. An age at FFTP of 25 versus 20 years lowered the risk for TNBC (OR=0.78, CI 0.70-0.88, p&lt;0.0001), but this effect was not apparent at a later FFTP. Conclusions: Our main findings suggest that parity is associated with TNBC across all ages at BC diagnosis, whereas the association with luminal HER2-like BC was present only for early onset BC.