Most sources consider that mothers receiving antineoplastic therapy should not breastfeed, especially with alkylating agents such as cisplatin.[1] Excretion of platinum into milk occurs, but results from case reports are inconsistent. Platinum in milk may increase with repeated courses of chemotherapy. The exact form(s), and toxicity of platinum excreted into breastmilk are also not known. The nursing infant would receive platinum compounds orally rather than intravenously and oral absorption of platinum compounds by infants is not known. It appears that it is not safe to breastfeed after cisplatin chemotherapy, and breastfeeding should probably be discontinued.
Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk.[2] Women who receive chemotherapy during pregnancy are more likely to have difficulty nursing their infant.