Iodine I-125 and Breastfeeding

Summary of use during lactation

Iodine I-125 is usually implanted temporarily in a sealed container (plaque or seed) to treat localized tumors. Modeling has shown that when a I-125 seed is implanted within 14 days prior to surgery for breast cancer, contact is considered safe on the contralateral side (i.e., the opposite breast). When the patient prefers to breastfeed or have close contact on the ipsilateral side (the side of the breast cancer), a daily limit of 5 hours ensures that the infant’s cumulative radiation exposure remains below the 1 mSv threshold.[1] The mother’s milk is not affected, and it can be pumped and fed to the infant at a later time.

Drug levels in milk and infant serum

Maternal Levels. Relevant published information was not found as of the revision date. Infant Levels. Relevant published information was not found as of the revision date.

Effects in breastfed infants

Relevant published information was not found as of the revision date.

Effects on lactation and breastmilk

A mother nursing an 11-month-old infant was treated with an iodine I-125 plaque for uveal melanoma. The plaque was in place for 2 days during which time she was separated from her infant, but pumped milk for later use. Breastfeeding was resumed after plaque removal.[2]

References

1. Heeling E, van de Kamer JB, Bruining A, et al. The safe use of (125)I-seeds as a surgical localization technique for breast cancer patients during breastfeeding and close contact with an infant. Clin Breast Cancer 2025;25:634–42.e4.40506302 PubMed
2. Rieth E, Barnett K, Simon J. Perioperative management of a lactating cancer patient undergoing surgical placement and removal of an iodine-125 brachytherapy plaque for uveal melanoma. Breastfeed Med 2020;15:A3–A4. doi:10.1089/bfm.2020.29162.abstracts