Coffee with Komen – Breastfeeding & Breast Cancer

By Laura Farrington, DO, Medical Oncologist at Cancer Treatment Centers of America, Midwestern Regional Medical Center

Breastfeeding is a complex task tackled by many mothers and can be beneficial for both the health of the infant and the mother. Studies indicate that any breastfeeding decreases a woman’s risk of breast cancer by about 30 percent, perhaps more if nursing for longer than six months.  This has even been shown in women with a BRCA1 mutation, who have a high risk of getting breast cancer.

The mechanism by which breastfeeding decreases breast cancer risk sparks a bit of controversy.  Pregnancy and breastfeeding reduce the number of menstrual cycles a woman has and her exposure to endogenous hormones, which are associated with breast cancer risks.  There are also researchers who hypothesize that pregnancy and breastfeeding have direct effects on the breast cells, causing them to differentiate, so they can produce milk, which may be more resistant to transforming into cancer cells.

Studies also indicate that breastfeeding in the past is associated with a decreased risk of breast cancer-specific death.  Breastfeeding may also decrease the risk of maternal diabetes and even potentially reduce the offspring’s risk of cancer.

Diagnosing breast cancer during pregnancy or breastfeeding may prove difficult and delay diagnosis.  Symptoms of breast cancer are similar to symptoms that may occur during nursing or mastitis including feeling a mass, having pain, nipple discharge, and redness.  A negative mammogram or ultrasound during lactation is very reassuring, however false positive or indeterminate results are more common, with only 10-40 percent being cancerous at biopsy in one study. There is also reluctance among providers to push for imaging and biopsy, as most of these symptoms are common and not cancerous during lactation.

A breast cancer diagnosis during pregnancy and breastfeeding, however, can complicate treatment.  Women who have had a recent pregnancy are at a slightly increased risk from the general population for about 10 years of getting breast cancer, likely due to the hormonal changes.  Some parts of breast cancer treatment can be done safely during pregnancy, including certain types of chemotherapy.

If a patient is breastfeeding and diagnosed with breast cancer, most physicians will recommend stopping breastfeeding. Many therapies used during breast cancer treatment can pass through breast milk and into the baby, including chemotherapies and hormone therapies, and even anesthesia during surgery.  Stopping breastfeeding will also decrease blood flow to the breast, making them smaller, easier to examine, and decrease the risk of infection to the breasts.

Certain chemotherapies may decrease fertility, but many women are able to conceive after breast cancer treatment, even if they have received chemotherapy, radiation and hormone therapy.  Breastfeeding after breast cancer local therapy (surgery and radiation therapy) can be challenging but should not be discouraged.  Radiation and surgery may decrease milk supply to the affected breast, but the opposite breast should still be able to produce milk.

Breastfeeding challenges many new mothers and an added new breast cancer or previously treated breast cancer can complicate the situation.  It is important to discuss these issues with your physicians if you are currently breastfeeding or plan to breastfeed in the future.

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