title: Safety of pregnancy after primary breast carcinoma in young women: a meta-analysis to overcome bias of healthy mother effect studies.
abstract: BACKGROUND
  An increased number of women are expected to conceive after the diagnosis of early breast cancer. Most physicians recommend that pregnancy be delayed by 2 to 3 years after diagnosis of early breast cancer, but this recommendation is based on data from trials with small patient cohorts. Furthermore, a healthy mother effect (HME) selection bias may be operative in most of these studies, because women undergoing childbearing after treatment were healthier when compared with the control group.
  
  
  OBJECTIVE
  To perform a systematic review and meta-analysis of published trials corrected for HME bias so as to assess the effect of pregnancy (at least 10 months after diagnosis) versus no pregnancy on overall survival of primary breast cancer patients less than 45 years.
  
  
  METHODS
  We searched MEDLINE and Thomson Reuters (ISI) Web of Knowledge for eligible studies. From each study we extracted the relative hazard ratio or, if not provided, all the necessary data to impute it. In cases where the duration from diagnosis to pregnancy was not reported, we extracted relevant data to estimate it.
  
  
  RESULTS
  Our electronic search strategy yielded 1623 hits pertaining to 20 potentially eligible studies involving 49,370 premenopausal breast cancer patients. Ten studies were eligible after considering HME potential bias in matching controls. Among these, 9 studies (pregnant 1089, matched-controls 13051) contained data appropriate for analysis. Overall survival was statistically higher among patients who became pregnant compared to controls: fixed effect model estimated pooled hazard ratio for death 0.51 (95% confidence interval: 0.42-0.62). No study heterogeneity was observed: Q = 10.4, P = 0.17; I(2) = 48%.
  
  
  CONCLUSIONS
  The pooled available evidence indicates that in early breast cancer patients, pregnancy that occurs at least 10 months after diagnosis does not jeopardize prognosis and may actually confer significant survival benefit.
  
  
  BACKGROUND
  Obstetricians & Gynecologists, Family Physicians.
  
  
  OBJECTIVE
  After completing this CME activity, physicians should be better able to assess the effect pregnancy has on long-term survival in primary breast cancer patients under age 45; counsel patients on the safety of pregnancy after breast cancer diagnosis and treatment; and interpret how pregnancy may be associated with improved breast cancer survival.
authors.affiliation: Onkologkliniken Sörmland, Mälarsjukhuset, Central Hospital of Eskilstuna, Eskilstuna, Sweden. valachis@hotmail.com
authors.forename: Antonis
authors.initials: A
authors.lastname: Valachis
authors.forename: Lamprini
authors.initials: L
authors.lastname: Tsali
authors.forename: Lorenzo L
authors.initials: LL
authors.lastname: Pesce
authors.forename: Nikolaos P
authors.initials: NP
authors.lastname: Polyzos
authors.forename: Charalambos
authors.initials: C
authors.lastname: Dimitriadis
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Tsalis
authors.forename: Davide
authors.initials: D
authors.lastname: Mauri
mesh_terms: D015982:Bias; D001943:Breast Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D005260:Female; D006801:Humans; D015201:Meta-Analysis as Topic; D011247:Pregnancy; D011252:Pregnancy Complications, Neoplastic; D011256:Pregnancy Outcome