As the most common malignancy in women worldwide, breast cancer will affect many women who are also actively breastfeeding or hope to breastfeed in the future. With so many potential complications for both mother and infant, the Academy of Breastfeeding Medicine released new guidelines for clinicians and multi-disciplinary teams.

“This protocol is a guide for mothers who are undergoing diagnosis and treatment for breast cancer,” said Arthur Eidelman, MD, editor-in-chief of Breastfeeding Medicine, in a statement. “It emphasizes that they do not have to categorically give up on their nurturing role as breastfeeding moms.”

Women diagnosed with breast cancer while breastfeeding may receive treatments that decrease milk production or are contraindicated during lactation and women diagnosed before or during pregnancy may have reduced lactational capacity or other irreversible effects, according to the study. Based on these complications, the guidelines state that women with a new or remote breast cancer diagnosis should have unique lactation support.

In women who have not been diagnosed with breast cancer, the authors said some debate continues about whether routine cancer screenings should continue. The American College of Radiology recommended the continuation of routine screenings, but guidelines vary between countries and debates exist regarding screening eligibility, method, and interval, according to the guideline authors.

Women planning to breastfeed for at least 6 months should continue routine screenings, according to the updated guidelines. Breastfeeding or expressing breast milk before the imaging will reduce differences in the images and possible false-positive screenings, according to the study. The authors added that women who plan to breastfeed for less than 6 weeks may defer mammography or magnetic resonance imaging until 6-8 weeks after they stop breastfeeding.

In women with a history of breast cancer, antepartum medical visits should include review of their treatments and a discussion of how breastfeeding may be affected. The patient should also be reassured that breastfeeding has not been shown to increase the risk of recurrent disease.

Breast cancer survivors who want to use galactogogues to augment milk production should be informed that many of these substances are phytoestrogens, which could, in concentrated supplement form, promote tumorigenesis or decrease endocrine therapy efficacy, according to the study.

Women with a history of total mastectomy should plan for unilateral breastfeeding, according to the guidelines. In cases of nipple areolar complex (NAC) preservation, the patient should know that the NAC will not be functional for breastfeeding, although some residual breast tissue can hypertrophy during pregnancy, which could give the appearance of functionality.

Women with a history of breast conservation therapy should expect significantly reduced milk production on the affected side, although it’s important to note that a single breast can produce sufficient milk for healthy infant growth. The authors added that providers should follow postpartum dyads closely to ensure adequate infant weight gain.

Pregnant women who are diagnosed with breast cancer can face significant risks, as treatments for pregnancy-associated breast cancer (PABC) can impact the developing fetus, future fertility, and breastfeeding. The authors emphasized that maternal and fetal survival are the utmost priority, but breastfeeding support is also a vital part of the treatment plan. Psychologist inclusion in the multidisciplinary team is also recommended in the new guidelines.

Treatment options can vary depending on the trimester in which the malignancy is diagnosed, as well as other factors such as cancer stage and tumor characteristics. Generally, the authors said breast surgical therapy consists of a total mastectomy when PABC is diagnosed in the first trimester. Further, they added that breast conservation surgery may be an option when the malignancy is diagnosed in the second or third trimesters, with deferment of adjuvant breast radiation until the postpartum period.

Finally, the authors said patients who receive chemotherapy during pregnancy have significantly reduced lactational ability. Chemotherapy is contraindicated during the first trimester and is generally paused 3-4 weeks before delivery. Many patients with PABC who require chemotherapy will receive part of their therapy during pregnancy and will complete a standard 4- to 6-month course after delivery.

The authors concluded the study with several recommendations for further research, including investigation of the establishment of a repository of breast milk from women with breast cancer in order to enable biospecimen studies, as well as evaluation of milk samples from women who choose to express during and after chemotherapy, targeted anti-human epidermal growth factor receptor 2 therapy, or endocrine therapy.

REFERENCE
Johnson H, Mitchell K, Noble L, et al. ABM Clinical Protocol #34: Breast Cancer and Breastfeeding. Breastfeeding Medicine; June 9, 2020. https://www.liebertpub.com/doi/10.1089/bfm.2020.29157.hmj?utm_source=Adestra&utm_medium=email&utm_term=&utm_content=Click%20here&utm_campaign=BFM%20PR%20June%2011%202020. Accessed June 18, 2020.