2957 - Infant Feeding and Lactation Outcomes after Breast-Conserving Treatment with Radiotherapy for Invasive Breast Cancer

Purpose/Objective(s): Information is limited describing infant feeding outcomes for breast cancer survivors who go on to give birth. We assessed lactation outcomes for women with a history of breast-conserving treatment with lumpectomy and breast radiotherapy (RT).

Materials/Methods: We conducted an IRB-approved survey of patients with invasive breast cancer (IBC) who underwent lumpectomy and RT and had sat least one live birth between 2010-2024. This mixed methods study included patient-reported preconception lactation counseling, feeding outcomes following delivery, and free text experiences. Dosimetry was also reported for patients who received RT at the sponsoring institution.

Results: Accrual began September 2024. Upon interim analysis, 12 patients have participated. Four of 12 (33%) patients reported receiving preconception lactation counseling, with their oncology team listed as an information source for all patients. Four patients considered or planned on exclusive formula feeding; common reasons cited were emotional trauma and physical toll of breastfeeding following cancer treatment; no patients were offered medical lactation suppression. Eleven of 12 patients attempted breastfeeding, all of whom were able to breastfeed to some extent. After delivery, in the irradiated breast, expression of colostrum was noted in 2/12, leakage of milk in 2/12, and engorgement in 3/12; no patients experienced clogged ducts or mastitis. All patients reported receiving lactation support postpartum: 11/11 from hospital lactation consultant, 2/11 from an OB/Gyn or Midwife, 3/11 from a private lactation consultant, and 1/11 from a support group. Three exclusively breastfed, while 8 required supplementation; all reported the untreated breast as the source of milk supply. One patient was breastfeeding at the time of the survey; 3 breastfed for 2-4 months, 3 for 4-6 months, 3 for 6-12 months, and 1 for 1-2 years. Common reasons for discontinuation included: insufficient milk supply (n=6), emotional toll of breastfeeding (n=3), physical toll of breastfeeding (n=3), and resumption of contraindicated anti-cancer therapy (n=2). Qualitative themes that emerged included societal pressure to breastfeed, trauma of breast cancer, and the need for greater support and education regarding both the ability to breastfeed after treatment as well as expectations for production from each breast.

Dosimetry was available for 6 patients who received treatment at our institution; all were treated with 3D-conformal RT. Median maximum EQD2 to the ipsilateral and contralateral breast was 61 Gy (range 48-64) and 1.13 (range 0.59-2.55), respectively, and median V1Gy to the contralateral breast was 0.19% (range 0-12).

Conclusion: Our findings highlight the need for improved pre-conception counseling and tailored lactation support for IBC survivors, particularly in setting expectations for milk production and addressing the emotional and physical challenges of breastfeeding after treatment.