DIANA WEST, BA, IBCLC
Originally published December 2011, updated November 2015 and republished with the express permission of the author.
Here are answers to some of the most common questions mothers have when facing the possibility or reality of cancer while breastfeeding:
Breastfeeding from a breast with cancer will not give the baby cancer in any way.
Babies will NOT always refuse to feed from a cancerous breast, although babies have been known to refuse a breast when the taste of the milk changes or the milk supply decreases due to malignant tissue growth.
Microcalcifications are tiny calcium deposits in breast tissue that occur more frequently in women who have breastfed, particularly for extended periods. Even distributions are normal and usually not an indication of cancer. Deposits in clusters are more likely to be malignant.
Imaging techniques used for diagnosis of pathology (such as ultrasound, mammogram, magnetic resonance imaging (MRI), positron emission tomography (PET) scan, 2-Methoxy Isobutyl Isonitrile (MIBI) scan, electrical impedance tomography (EIT) scan, computed tomography (CT) scan/computer axial tomography (CAT) scan, thermography, or diaphanography) are non-invasive and do not affect milk production or safety. It may be more difficult to interpret breast tissue results due to the increased density from lactation, but it is not impossible. It is not necessary to interrupt or suspend breastfeeding to have these procedures.
A ductogram, in which a catheter is inserted into a lactation duct through the nipple to either inject radioactive dye that can be detected on x-ray or insert a miniature camera to visualize the internal duct walls, does not affect milk production or safety since there are no incisions or tissue removal and the radioactive dye is not absorbed into either the mother’s or the baby’s tissue (see below).
Needle aspiration to remove the contents of fluid-filled cysts and galactoceles does not affect milk production or safety.
Biopsy to remove tissue for diagnostic analysis can damage lactation ducts or nerves depending on the technique, amount of tissue removed and location of the incision. Incisions in the upper, inner quadrants of the breast are usually least harmful, while incisions around the areola can damage nerve response affecting milk ejection. Scars or infections from a biopsy also may harm the milk-making tissue. Some surgeons may be reluctant to perform biopsies on a lactating breast because it can be more difficult to see the affected tissue, but it can be done and the milk will not delay wound healing. There is a risk that a milk-filled cyst (called a galactocele) could develop, but it can be treated with needle drainage (aspiration). If infection occurs, it can be treated with antibiotics that are safe for breastfeeding.
Radiation from diagnostic procedures using x-rays, mammograms, MRI, and CT/CAT scans are all safe during lactation. While this kind of radiation does have the ability to mutate DNA in live cells, it does not collect in the milk and is therefore compatible with uninterrupted breastfeeding. Radiopaque and radiocontrast agents typically used in ductogram, CT/CAT, MRI, MIBI scan, or PET scan diagnostic tests are extremely inert and virtually unabsorbed when taken orally, so they do not pass into the milk and it is not necessary to interrupt breastfeeding when they are used.
Radioactive isotopes, including radioactive iodine, used for diagnostic testing or therapy are NOT safe during breastfeeding because these compounds accumulate in milk and are hazardous to the baby. Radioactive iodine-131 in particular is not only NOT safe for breastfeeding because the affected milk can harm the baby, but the mother is also at risk of radiation saturation into breast tissue, putting her at higher risk for breast cancer. Use of this particular iodine requires complete weaning several weeks beforehand to allow her breast tissue time to involute so there is less tissue to be harmed. For use of other types of radioactive isotopes, it is not necessary to completely wean. A mother only needs to interrupt breastfeeding temporarily, feeding her infant previously pumped milk or formula until tests (available from most hospital radiology departments) show that the isotopes are no longer in her milk. In the meantime, she can pump and discard the milk to keep up her milk supply and accelerate radiation removal. For a list of radioactive isotopes and the length of time they remain in the milk, visit neonatal.ttuhsc. edu.
Radiation therapy is destructive to milk-making tissue and likely to reduce milk production capability, sometimes completely. However, the breast that did not receive radiation will not be affected and is safe to breastfeed from.
Breastfeeding during chemotherapy is absolutely contraindicated because the medications used to eradicate cancer are highly toxic and transfer into milk. Breastfeeding after chemotherapy has been completed may be possible, either by relactation or as a result of another pregnancy, depending upon the drugs that were used.
Local anesthesia does not transfer into milk in detectible levels, so it is not necessary to interrupt breastfeeding in any way when it is used.
General anesthesia does not require weaning or the interruption of breastfeeding. As soon as a mother awakes fully from general anesthesia, it is safe to nurse her baby or pump her milk because general anesthetic medications are rapidly metabolized. When she is no longer drowsy, the anesthetic medications are no longer active in her milk.
Weaning for diagnostic or tissue-removal surgery is almost never necessary or helpful. Since milk can continue to be produced for many months after weaning, there is almost always residual milk in the ducts. Abrupt weaning can result in plugged ducts and infectious mastitis. To minimize milk seepage during the procedure, the breast can be thoroughly drained by nursing or pumping immediately prior to the diagnostic or tissue-removal surgery.
Weaning will not help a mother “conserve her strength.” Breastfeeding is considerably more convenient and time-saving than bottle-feeding. It provides an emotional connection and intimacy that is nurturing to both mother and baby when they need it most.
The risk of breast cancer recurrence is not increased by breastfeeding.
Lumps and Mammograms
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Diana West, BA, IBCLC, is an LLL Leader and one of the co-authors of the LLLI books The Womanly Art of Breastfeeding and Sweet Sleep. She is co-author with Lisa Marasco, MA, IBCLC, of The Breastfeeding Mother’s Guide to Making More Milk, and with Dr. Elliot Hirsch of Breastfeeding After Breast and Nipple Procedures. She is also author of the Clinician’s Breastfeeding Triage Tool and Defining Your Own Success: Breastfeeding After Breast Reduction Surgery.