Breastfeeding and Breast Cancer: What You Need to Know
The American Society of Breast Surgeons has recently released its first official guidelines on oncolactation — a term that describes how breastfeeding and breast-cancer care intersect.* These new recommendations are an important step in helping women who are diagnosed with breast cancer during pregnancy, while breastfeeding, or after treatment to make safe and informed decisions.
Breast Cancer During Pregnancy or While Breastfeeding
Pregnancy and breastfeeding cause normal breast changes that can make it harder to interpret imaging tests, but breast cancer can still be safely diagnosed and treated during these times.
Safe tests during pregnancy and lactation:
Ultrasound and mammogram are both safe in pregnancy and while breastfeeding.
No need for lead shields during mammogram – the radiation to the baby is extremely low.
MRI scans should be avoided in pregnancy as MRI contrast can pass through the placenta, but it is safe while breastfeeding.
You don’t need to stop breastfeeding before or after any of these imaging tests.
Just feed or pump right before the scan to make the pictures clearer.
If you find a lump or change in your breast, don’t delay getting it checked — breast cancer linked to pregnancy or postpartum can behave aggressively if not treated early.
Breast Cancer Treatment and Breastfeeding
Each treatment affects breastfeeding differently.
Surgery:
Surgery should not be delayed because of breastfeeding — complications like milk fistula are rare.
You can usually keep feeding from the other breast if only one is affected.
Sometimes a temporary drain is used to reduce fluid build-up if milk production is high.
Local anaesthetic and most pain medications are safe while breastfeeding (avoid codeine, tramadol, and pethidine).
Radiation:
Do not breastfeed from the breast being treated with radiotherapy — it can damage milk-producing cells and cause skin problems.
You can still feed safely from the other breast.
Chemotherapy & Hormone Therapy:
Do not breastfeed while on chemotherapy, endocrine therapy, or new targeted drugs, as these can pass into breast milk.
Once chemotherapy begins, milk supply can be stopped safely with medications if needed.
Pumping to maintain supply during chemotherapy is generally discouraged due to infection and milk safety concerns.
Breastfeeding After Breast Cancer Treatment
Many survivors can still breastfeed — often from the unaffected breast.
After Surgery:
Mastectomy removes nearly all milk-producing tissue, so the treated side cannot breastfeed.
Lumpectomy (breast-conserving surgery) may still allow breastfeeding if the nipple and milk ducts are intact.
After radiation:
The treated breast usually cannot produce milk normally.
Some women may make small amounts, but feeding or pumping from that side isn’t recommended.
After chemotherapy:
Milk production may be lower, but breastfeeding from the opposite breast is often possible.
Breastfeeding does not increase cancer recurrence risk — in fact, it may help reduce future cancer risk.
Planning for the Future
If you are considering preventive (risk-reducing) mastectomy, it’s important to know:
Such surgery may permanently stop your ability to breastfeed.
For many women, it’s reasonable to delay preventive surgery until after completing their family, as breastfeeding offers many long-term health benefits — including lowering ovarian cancer risk for BRCA carriers.
Key Takeaways
Breast imaging is safe in pregnancy and breastfeeding — don’t delay care.
Many women can continue or resume breastfeeding after breast cancer.
Always discuss your breastfeeding wishes with your surgeon and oncologist early in your treatment plan.
With the right planning and support, motherhood and survivorship can coexist safely and beautifully.