Evaluation of Platinum Transfer to Breast Milk in Cervical Cancer Patient Undergoing Cisplatin-Based Chemotherapy

The risk of platinum exposure in infants breastfed by mothers receiving chemotherapy with a platinum-containing agent remains unclear. From the perspective of toxicity, both quantification and speciation of platinum in breast milk are needed. We collected breast milk samples from a cervical cancer patient who underwent six cycles of cisplatin-based chemotherapy after childbirth. Samples were collected during the fifth and sixth cycles, and platinum concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS). Platinum speciation was investigated by liquid chromatography hyphenated with ICP-MS. Platinum concentration in breast milk increased immediately after cisplatin administration and then declined rapidly, reflecting the distribution and excretion of the majority of cisplatin in the body. However, platinum concentration in breast milk remained above 5 µg/L for up to three weeks, suggesting that the secretion of platinum into breast milk continues over a prolonged period. Speciation analysis revealed that at trough levels before cisplatin administration, platinum was primarily bound to serum albumin. Immediately after administration, lactalbumin-bound platinum increased but disappeared within 6 h. After the protein fraction was digested with simulated gastrointestinal fluid, part of the protein-bound platinum was converted into low-molecular-weight compounds. However, no free cisplatin was released from the proteins. We revealed the concentration and speciation changes of platinum in breast milk during cisplatin-based chemotherapy. However, the toxicity of low-molecular-weight platinum compounds after digestion remains unclear. Further investigation is needed to assess the safety of lactation during cisplatin-based chemotherapy.