Pregnancy and Breast Cancer

The purpose of this guideline is to describe the diagnosis, management and treatment of breast cancer during and immediately after pregnancy. It also provides advice on future fertility considerations after a breast cancer diagnosis.

This guideline is for healthcare professionals who care for women, non-binary and trans people who experience pregnancy associated breast cancer (PABC). Within this document we use the terms woman and women's health. However, it is important to acknowledge that it is not only women for whom it is necessary to access women's health and reproductive services in order to maintain their gynaecological health and reproductive wellbeing. Gynaecological and obstetric services and delivery of care must therefore be appropriate, inclusive and sensitive to the needs of those individuals whose gender identity does not align with the sex they were assigned at birth.

Breast cancer is the most common cancer in the UK, accounting for 15% of all new cancer cases (2017–19) [1]. There are around 56 800 new breast cancer cases in the UK every year (2017–19) [1]. Of these, 9% occur in women at or under 44 years of age [1]. Survival rates have improved significantly in recent decades. In women diagnosed under the age of 39 years, 85% are alive more than 5 years after their diagnosis [1] leading many women to now consider pregnancy as an option after cancer.

A new breast cancer diagnosis complicates about 1 in 3000 pregnancies [2]. With advancing maternal age at pregnancy [3] it is likely that the incidence of breast cancer during pregnancy will increase.

Clinical care of people who are pregnant with breast cancer should follow the principles of care for all pregnant women with medical disorders: the clinician's duty of care is first towards the woman and then to the fetus. This principle was outlined in the 2021 MBRRACE report which states that clinicians should ‘Treat women who may become pregnant, are pregnant, or who have recently been pregnant the same as a non-pregnant person unless there is a very clear reason not to’ [4]. For pregnant women with breast cancer a care plan should first be established by surgeons and oncologists, as if the woman was not pregnant. This plan can then be adapted with a multidisciplinary team (MDT) that should also include obstetricians, fetal and neonatal specialists. This team should balance potential treatment for the woman and her fetus with potential compromise for pregnancy outcome. These treatment options must be discussed with the woman.

As breast cancer during pregnancy is relatively rare and heterogeneous in its presentation, recommendations for care are guided by international registries rather than clinical trials. Treatment decisions are therefore limited to the best available evidence, which is often not definitive. In the absence of evidence of harm or safety in pregnancy, MDTs may need to consider treatment which is in the best interest for the woman. Pregnancy is not, however, an exception to the principle that an informed patient has the right to refuse treatment, even treatment needed to maintain life and a pregnant woman's informed decision to refuse recommended medical or surgical interventions for breast cancer should be respected [5].

The Cochrane Library (including the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects [DARE] and the Cochrane Central Register of Controlled Trials [CENTRAL]), EMBASE, Trip, MEDLINE and International HTA database were searched for relevant papers. Databases were searched using the relevant Medical Subject Headings (MeSH) terms, including all subheadings and synonyms, and this was combined with a keyword search. Search terms included: ‘pregnancy’, ‘breast cancer’, ‘inflammatory breast neoplasm’, ‘pregnancy complications’ and ‘breastfeeding’. The search was limited to studies on humans and papers in the English language and included all relevant studies 2010 until December 2023. Relevant guidelines were also searched for using the same criteria in the ECRI Guidelines Trust (replaces National Guideline Clearinghouse), Guidelines International Network and the National Institute for Health and Care Excellence (NICE) Evidence Search.

This guideline was developed using the methodology described in the Royal College of Obstetricians and Gynaecologists (RCOG) handbook Developing a Green-top Guideline: Guidance for developers. Where possible, recommendations are based on available evidence. Areas lacking evidence are highlighted and annotated as ‘good practice points’. Further information about the assessment of evidence and the grading of recommendations may be found in Appendix A.

Audit of current practice, benchmarked against the above guidance, can provide a valuable lever for change and improvement. Possible topics that could be considered for audit are shown in Table 1.

RCOG patient information Pregnancy and breast cancer

Mummy's Star

Breast Cancer Now

Cancer Research UK

Macmillan Cancer Support

The guideline will be considered for update 3 years after publication, with an intermediate assessment of the need to update 2 years after publication.