Treating Breast Ca During Pregnancy? (New Guidance)

Breast cancer is an hormone responsive malignancy, meaning it may use estrogen and progesterone, reduced in high quantities during a pregnancy, for growth. However, as medical evidence evolves quickly, physicians have come to understand that breast cancer diagnosis during pregnancy doesn't always mean worse prognoses. While older studies- including meta analysis-reflected worse prognoses for pregnancy related breast cancer compared to non-pregnancy related cases, these studies either included studies from the 1960s and 70s when diagnosis and treatment were radically different, had inconsistent definitions of PABC, and/or were poorly age and staged matched. Therefore, as stated in the new UK (Aug 2025) guidance, “the applicability to modern day practice of the findings from these reports is limited”. The more updated clinical stance is that, “By using diagnostic and treatment pathways for women with {pregnancy related breast cancer} which are as close as possible to women with non-pregnancy related breast cancer, similar outcomes can be achieved” (RCOG Green Top recommendations No 12). In this episode, we will summarize key points from the recently released Green Top Guidance No 12 (25 Aug 2025) which has shifted the perspective on treating breast cancer DURING pregnancy.

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2. https://www.rcog.org.uk/guidance/browse-all-guidance/green-top-guidelines/pregnancy-and-breast-cancer-green-top-guideline-no-12/

3. Sundermann AC, Cate JM, Campbell AK, Dotters-Katz SK, Myers ER, Federspiel JJ. Maternal morbidity and mortality among patients with cancer at time of delivery. Am J Obstet Gynecol. 2023 Sep;229(3):324.e1-324.e7. doi: 10.1016/j.ajog.2023.06.008. Epub 2023 Jun 7. PMID: 37295633; PMCID: PMC10593119.