title: Prognostic impact of pregnancy after breast cancer according to estrogen receptor status: a multicenter retrospective study.
abstract: OBJECTIVE
  We questioned the impact of pregnancy on disease-free survival (DFS) in women with history of breast cancer (BC) according to estrogen receptor (ER) status.
  
  
  METHODS
  A multicenter, retrospective cohort study in which patients who became pregnant any time after BC were matched (1:3) to patients with BC with similar ER, nodal status, adjuvant therapy, age, and year of diagnosis. To adjust for guaranteed time bias, each nonpregnant patient had to have a disease-free interval at least equal to the time elapsing between BC diagnosis and date of conception of the matched pregnant one. The primary objective was DFS in patients with ER-positive BC. DFS in the ER-negative cohort, whole population, and overall survival (OS) were secondary objectives. Subgroup analyses included DFS according to pregnancy outcome and BC-pregnancy interval. With a two-sided α = 5% and β = 20%, 645 ER-positive patients were required to detect a hazard ratio (HR) = 0.65.
  
  
  RESULTS
  A total of 333 pregnant patients and 874 matched nonpregnant patients were analyzed, of whom 686 patients had an ER-positive disease. No difference in DFS was observed between pregnant and nonpregnant patients in the ER-positive (HR = 0.91; 95% CI, 0.67 to 1.24, P = .55) or the ER-negative (HR = 0.75; 95% CI, 0.51 to 1.08, P = .12) cohorts. However, the pregnant group had better OS (HR = 0.72; 95% CI, 0.54 to 0.97, P = .03), with no interaction according to ER status (P = .11). Pregnancy outcome and BC-pregnancy interval did not seem to impact the risk of relapse.
  
  
  CONCLUSIONS
  Pregnancy after ER-positive BC does not seem to reduce the risk of BC recurrence.
authors.affiliation: Department of Medical Oncology, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium. hatem.azim@bordet.be
authors.forename: Hatem A
authors.initials: HA
authors.lastname: Azim
authors.forename: Niels
authors.initials: N
authors.lastname: Kroman
authors.forename: Marianne
authors.initials: M
authors.lastname: Paesmans
authors.forename: Shari
authors.initials: S
authors.lastname: Gelber
authors.forename: Nicole
authors.initials: N
authors.lastname: Rotmensz
authors.forename: Lieveke
authors.initials: L
authors.lastname: Ameye
authors.forename: Leticia
authors.initials: L
authors.lastname: De Mattos-Arruda
authors.forename: Barbara
authors.initials: B
authors.lastname: Pistilli
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pinto
authors.forename: Maj-Britt
authors.initials: MB
authors.lastname: Jensen
authors.forename: Octavi
authors.initials: O
authors.lastname: Cordoba
authors.forename: Evandro
authors.initials: E
authors.lastname: de Azambuja
authors.forename: Aron
authors.initials: A
authors.lastname: Goldhirsch
authors.forename: Martine J
authors.initials: MJ
authors.lastname: Piccart
authors.forename: Fedro A
authors.initials: FA
authors.lastname: Peccatori
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000378:metabolism / Q000401:mortality* / Q000628:therapy; D016022:Case-Control Studies; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008408:Mastectomy; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000378:metabolism / Q000401:mortality* / Q000628:therapy; D009367:Neoplasm Staging; D011247:Pregnancy; D011252:Pregnancy Complications, Neoplastic / Q000378:metabolism / Q000401:mortality* / Q000628:therapy; D011256:Pregnancy Outcome; D011960:Receptors, Estrogen / Q000378:metabolism*; D012189:Retrospective Studies; D015996:Survival Rate; D055815:Young Adult
chemical_list: D011960:Receptors, Estrogen