Breastfeeding After Hormone Receptor–Positive Breast Cancer: Results From the POSITIVE Trial
Mené sur 313 patientes atteintes d'un cancer HR+ de stade précoce (durée médiane de suivi : 41 mois), cet essai prospectif analyse le nombre de naissances et les comportements d'allaitement
Purpose: We investigated breastfeeding patterns, behaviors, and association with breast cancer (BC) outcomes in women with early hormone receptor–positive (HR+) BC who had a live birth in the POSITIVE trial.
Patients and Methods: POSITIVE is a prospective trial that demonstrated no increased short-term risk of BC events in women with early HR+ BC who interrupted endocrine therapy (ET) to attempt pregnancy. We describe the frequency, duration, and laterality of breastfeeding and estimate the cumulative incidence of BC events by breastfeeding status.
Results: At a median follow-up of 41 months, 317 patients had at least one live birth and 313 were eligible for this analysis. A total of 196 of 313 (62.6%) patients breastfed. A total of 130 of the 167 women (77.8%) who had breast-conserving surgery breastfed, and 90 of 130 (69.2%) breastfed from the unaffected breast only. Sixty-six of the 146 women (45.2%) who underwent unilateral mastectomy breastfed. The frequency of breastfeeding was higher in women older than 35 years (67.6% v 55.7%) and in those without previous children (66.4% v 48.5%). Over half (103 of 196, 52.6%) of women breastfed their first live birth for >4 months (median 4.4 months; 95% CI, 4.0 to 5.3). The cumulative incidence of a BC event at 24 months from first on-study live birth was 3.6% and 3.1% in the breastfeeding and nonbreastfeeding groups, respectively (0.5% difference; 95% CI, –4.3% to 5.2%).
Conclusion: In POSITIVE, two thirds of women who gave birth after BC diagnosis breastfed, mostly for 4 months or more. In early follow-up, we did not observe differences in BC-related events in women who breastfed compared with those who did not. These results are key for women who wish to pursue pregnancy and breastfeeding after BC.
Journal of Clinical Oncology , résumé, 2025