ESMO Expert Consensus Statements on the management of breast cancer during pregnancy (PrBC)

The management of breast cancer during pregnancy (PrBC) is a relatively rare indication and an area where no or little evidence is available since randomized controlled trials cannot be conducted. In general, advances related to breast cancer (BC) treatment outside pregnancy cannot always be translated to PrBC, because both the interests of the mother and of the unborn should be considered. Evidence remains limited and/or conflicting in some specific areas where the optimal approach remains controversial. In 2022, the European Society for Medical Oncology (ESMO) held a virtual consensus-building process on this topic to gain insights from a multidisciplinary group of experts and develop statements on controversial topics that cannot be adequately addressed in the current evidence-based ESMO Clinical Practice Guideline. The aim of this consensus-building process was to discuss controversial issues relating to the management of patients with PrBC. The virtual meeting included a multidisciplinary panel of 24 leading experts from 13 countries and was chaired by S. Loibl and F. Amant. All experts were allocated to one of four different working groups. Each working group covered a specific subject area with two chairs appointed: 1. PrBC: incidence, epidemiology, biology and pathology, diagnostic work-up, staging and risk assessment, prognosis (Chairs: Vincent Vandecaveye, Fedro Peccatori). 2. Clinical pharmacology of systemic agents during pregnancy: management of localized disease and (neo) adjuvant therapies, management of systemic disease (Chairs: Giuseppe Curigliano, Peter Schmid). 3. Obstetric care and fetal/newborn follow-up and outcomes: metastases to fetus, management of pregnancy during anti-cancer therapy, lactation, psychological support (Chairs: Elyce Cardonick, Mathilde van Gerwen). Planning, preparation and execution of the consensus process was conducted according to the ESMO standard operating procedures.