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The Voice of People With Breast Cancer


Our Voices Blog

Breastfeeding Following a Breast Cancer Diagnosis

Breastfeeding has been linked to a few health benefits such as its ability to reduce the risk of being diagnosed with breast cancer.1 This may be because of reduced exposure to estrogen as well as the shedding of breast tissue.2 But what happens when breastfeeding cannot reduce your risk of breast cancer because you have already been diagnosed? While breastfeeding comes with its own challenges, having a newborn while dealing with a breast cancer diagnosis comes with its own unique complications. One of these is knowing whether you can breastfeed your child and how to go about it.

Surgeries, Treatments and When You Can Breastfeed

Whether you can or can’t breastfeed depends a lot on the type of cancer treatment or surgery you receive, and, in these cases, it is still advised to discuss with your primary care physician about the best route to take. We begin with treatment and surgeries where you won’t be able to breastfeed, followed by those where the decision is made on a case-by-case basis.

Double Mastectomy

Breastfeeding is not possible with a double mastectomy as there are no milk ducts left following this type of surgery.

Hormone Therapy

Long-term drugs, such as Tamoxifen or trastuzumab, get into breast milk and therefore, if you are on these, you will not be able to breastfeed your child.3


If you are currently receiving chemo, you cannot breastfeed. Chemo drugs kill rapidly growing cells and are therefore very toxic. Since these drugs can get into milk, it is not advised to breastfeed.

If you were on chemo, some time will have to pass before you can breastfeed, in this instance, ask your primary care physician, OB-GYN, child’s doctor, when you can safely begin breastfeeding. This ensures that you would have allowed for enough time for the chemo drugs to leave your system. If you do not have to wait a long time, you might be advised to “pump and dump” first, before nursing your baby right away.


Depending on how much breast tissue was removed, you should be able to breastfeed following a lumpectomy. With a lot of breast tissue removed, you may not produce a lot of milk but should be able to breastfeed from the untreated breast. If the milk from one breast is not enough, you might want to consider using formula as a supplement or seeking out a breast milk donor. Your doctor or a breastfeeding coach should be able to provide you with help on the appropriate step to take.

Single Mastectomy

A mastectomy involves removing only the affected breast, so breastfeeding is still possible from the unaffected breast. Once again, consider supplementing with formula if the milk from one breast is not enough and reach out to a breastfeeding coach or a lactation expert for more guidance.


While it is considered safe to breastfeed if your breast cancer is being treated by external beam radiation therapy, it is best to check with your primary care physician first, before doing so. In some cases, radiation can damage breast tissue, making it that the affected breast produces little to no milk. In this case, you can nurse from the untreated breast and use formula if the milk is not enough.


It is generally safe to breastfeed following anesthesia as it does not get transferred into milk.

Good Breastfeeding Practices

As always, your primary care physician will provide you with the best steps to take. Speak with them about the treatment and surgeries available to you to understand how this will affect your ability to breastfeed. While breastfeeding is a special bonding time for you and your child, your health and the baby’s health are most important. While you can keep in mind how your treatment and surgeries will affect breastfeeding, it is important to go with the best option in treating your breast cancer.

If you are able to continue breastfeeding but don’t have enough breast milk (which may be the case if you can only breastfeed from one breast) you can use formula as well as breast milk. If you go this route, you can look into getting a supplemental nursing system (SNS). This is a device where a narrow tube is taped to your breast, near your nipple, with the other end connected to a bottle of formula. If you have been breastfeeding and need to stop, it is better to wean your child than to just stop, if this is possible. This ensures that you do not have to deal with engorgement or mastitis. Lactation specialists can provide you with a schedule for weaning and pumping to reduce these risks. If you can’t breastfeed your child, look into breast milk donation if your main goal is to have a breastfed child.

Whichever route that you take, know that you are not less of a mother because you are unable to breastfeed your child or because you require extra precautions. Even without the added concern of a breast cancer diagnosis, new moms deal with various complications when it comes to breastfeeding. As long as your child is loved and being cared for, where their nutrition comes from is secondary.

Resources to Get You Started


Alberta Health Services – Lactation Services

Alberta Independent Registered Lactation Consultants

Northern Star Mothers Milk Bank

British Columbia

British Columbia Lactation Consultant Association

BC Women’s Provincial Milk Bank


Foundations Birth Services

The Birth Centre

Winnipeg Breastfeeding Centre

New Brunswick

Government of New Brunswick – Breastfeeding Support Services

Newfoundland and Labrador

Baby-Friendly Newfoundland and Labrador

Northwest Territories, Nunavut and Yukon

Monarch Centre

Riley Park Maternity Clinic

Whitehorse Health Centre

Nova Scotia

Good Latch

The Nurturing Touch


Bilingual Online Ontario Breastfeeding Services – IB Certified Lactation Consultant

Telehealth Ontario

The Rogers Hixon Ontario Human Milk Bank

Prince Edward Island

Health PEI - Breastfeeding your Baby and Baby Friendly Initiative


Association Québécoise des Consultantes en Lactation Diplomées de l'IBLCE

Héma-Québec – Public Mother’s Milk Bank

Breastfeeding problems and solutions


Saskatchewan Lactation Consultant Association

Saskatchewan Milk Bank


Canadian Lactation Consultant Association

La Leche League Canada

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