Breastfeeding after breast cancer in young BRCA carriers
Menée à partir de données portant sur 4 732 patientes atteintes d'un cancer du sein de stade I à III diagnostiqué avant l'âge de 40 ans et porteuses d'une mutation BRCA (durée médiane de suivi après accouchement : 7 ans), cette étude de cohorte rétrospective analyse l'impact de l'allaitement sur le risque de récidive locorégionale, le risque de développer un cancer du sein controlatéral, la survie sans maladie et la survie globale (659 grossesses, 474 naissances d'enfants)
Background: We investigated safety of breastfeeding after breast cancer in patients carrying germline BRCA pathogenic or likely pathogenic variants.
Methods: This was an international, multicentre, hospital-based, retrospective cohort study including BRCA carriers diagnosed with stage I-III invasive breast cancer at age 40 years or younger between January 2000 and December 2020 (NCT03673306). Locoregional recurrences and/or contralateral breast cancers, disease-free survival (DFS) and overall survival (OS) were compared between patients who breastfed after delivery and those who did not.
Results: Among 4732 patients included from 78 centres worldwide, 659 had a pregnancy after breast cancer diagnosis, of whom 474 delivered a child. After excluding patients with uptake of bilateral risk-reducing mastectomy prior to delivery (n = 225) or unknown breastfeeding status (n = 71), 110 (61.8%) breastfed (median duration 5 months) and 68 (38.2%) did not breastfeed. Compared to patients in the no breastfeeding group, those who breastfed were more frequently nulliparous at breast cancer diagnosis (61.8% vs 45.6%) and did not report prior smoking habit (71.8% vs 57.4%).
After a median follow up of 7.0 years following delivery, 7-year cumulative incidence of locoregional recurrences and/or contralateral breast cancers was 29% in the breastfeeding group and 37% in the no breastfeeding group (adjusted subdistribution hazard ratio[HR]=1.08, 95%CI 0.57-2.06). No difference in DFS (aHR = 0.83, 95%CI 0.49-1.41) nor in OS (aHR = 1.32, 95%CI 0.31-5.66) was observed.
Conclusions: Breastfeeding did not appear to be associated with a higher risk of developing locoregional recurrences or contralateral breast cancers, emphasizing the possibility of achieving a balance between maternal and infant needs without compromising oncological safety.
Journal of the National Cancer Institute , résumé, 2025