Current data suggest that breastfeeding does not affect breast cancer outcomes, and neither breastfed infants nor breastfeeding mothers with cancer have an increased risk of developing cancer as a result of breastfeeding. However, do various treatments such as surgery, chemotherapy, radiotherapy, and endocrine therapy have an impact on breastfeeding? The following recommendations are available.
Breast lactation can be affected after breast-conserving treatment
Patients with early-stage breast cancer who undergo breast-conserving surgery plus radiation therapy can successfully breastfeed on the side without the tumor (healthy side), and the breast on the diseased side (affected side) is functional but will produce significantly less milk. If the lesion is located in the central region of the breast, closer to the nipple areola, the breastfeeding function will be significantly reduced. Breast volume reduction after breast-conserving surgery, the dose of radiation therapy, and the sensitivity of the individual to radiation therapy can affect lactation function.
Avoid breastfeeding on the affected breast during radiation therapy
Compared to the contralateral normal breast, the affected breast that has undergone radiotherapy has reduced swelling, decreased lactation, and a change in milk composition during pregnancy and lactation, with a decrease in fat content and an increase in salt content. Therefore, although breastfeeding is possible during radiotherapy, it is important to avoid breastfeeding in the radiotherapy-side breast as it can be very difficult to manage because mastitis occurs in the breast tissue on the radiotherapy side.
Breastfeeding is not recommended during chemotherapy
The levels of chemotherapy drugs in breast milk are not known, so doctors usually do not recommend breastfeeding during chemotherapy to avoid damage to the baby from chemotherapy drugs passing through the breast milk. If chemotherapy has been completed and sufficient time has been allowed for drug metabolism and the drugs have been completely excreted, breastfeeding is possible.
Lactation is not recommended during endocrine, targeted therapy
The endocrine drug tamoxifen is potentially teratogenic and its use during pregnancy can lead to hermaphroditism, head and facial abnormalities, and oculo-ear spinal abnormalities in the fetus. Also, endocrine drugs can pass into breast milk, so breastfeeding should be discontinued during endocrine therapy.
The targeted drug trastuzumab may cross the placental barrier causing low amniotic fluid, and although it can recover on its own after discontinuation and fetal development is not affected, physicians do not recommend breastfeeding during trastuzumab therapy for safety reasons.
In addition, the composition of TCM is complex and the effects on the infant are not known; therefore, doctors do not recommend breastfeeding for those receiving TCM treatment. (Contributed by Ma Yue, Department of Medical Oncology, Shanghai Renji Hospital)