Accurate information about locoregional breast cancer treatments following neoadjuvant systemic therapy (NST) is essential for meaningful interpretation of oncological outcomes but reporting is currently poor. We developed a core outcome set (COS) to improve the quality and consistency of locoregional outcome reporting in breast cancer NST trials. The COS was developed in three phases according to COS-STAD guidance, with the generation of a list of relevant outcome domains, prioritisation of outcomes through two rounds of an international online multi-stakeholder Delphi survey and a consensus meeting. 159 unique locoregional outcomes were classified into 101 outcome domains for inclusion in the Delphi survey, which was completed by 470 international professionals. The final 15-item COS, which included the pre-NST surgical plan, details of surgery performed following completion of treatment and details of radiation therapy, was agreed at an in-person consensus meeting. Widespread COS implementation will improve the quality and value of future NST trials.
AimNeoadjuvant systemic therapy (neoSACT) is increasingly used in the treatment of early breast cancer, particularly triple negative and HER2-positive disease, as recommended in recently published UK multidisciplinary guidelines (1). Neoadjuvant treatment has several advantages. Pathological complete response (pCR) to neoSACT provides valuable prognostic information, which can be used to tailor adjuvant systemic therapies, resulting in improved survival outcomes for patients.
In addition, downstaging of disease using neoSACT can potentially allow de-escalation of locoregional treatments to the breast and axilla (e.g. facilitating targeted axillary dissection rather than axillary node clearance) (2, 3). These approaches can potentially improve outcomes for patients through reducing complications and morbidity.
However, surgical decision-making following neoSACT remains inconsistent, with many patients not offered response-adjusted surgery despite achieving a pCR (2-4).
One reason for this is that the evidence base underpinning surgical decision-making after neoSACT is poor. This is because important details of loco-regional treatment (such as information about surgical downstaging and specific details of procedures performed), are poorly reported in most neoSACT randomised controlled trials (RCT). Those outcomes which are reported are inconsistent and heterogenous, precluding meaningful comparisons between studies and hampering development of high-quality evidence to support informed decision-making. Similar inconsistency is seen in reporting of radiotherapy treatment regimens following neoSACT, again limiting cross-study comparisons but also, importantly, hampering the interpretation of loco-regional recurrence outcomes.
There is therefore an urgent need to improve reporting of locoregional therapies in neoSACT trials. Development of a core outcome set (COS), ‘an agreed standardised set of outcomes that should be measured and reported, as a minimum, in all clinical trials’ for locoregional treatment following neoSACT may be an effective way to achieve this.
The PRECEDENT study aims to develop a COS and reporting guidelines for locoregional treatments (surgery and radiotherapy) following neoSACT within clinical trials.
Shelley Potter, Kerry Avery, Rosina Ahmed, Jana de Boniface, Sanjoy Chatterjee, David Dodwell, Peter Dubsky, Jingjing Federmann, Sandra Finestone, Michael Gnant, Dominik Hlauschek, Hiroji Iwata, Michael Y. Jiang, Orit Kaidar-Person, Han-Byoel Lee, Mairead MacKenzie, Anne Meyn, Philip Poortmans, Fiorita Poulakaki, Andrea L. Richardson, Karla A. Sepulveda, Andrew J. Spillane, Alastair M. Thompson, Gustavo Werutsky, Philipp Wittmann, Jean L. Wright, Nicholas Zdenkowski, Katherine Cowan & Stuart A. McIntosh On behalf of the PRECEDENT Study Group
Disease Category: Cancer
Disease Name: Breast cancer
Age Range: 16 - 120
Sex: Female
Nature of Intervention: Other
- Clinical experts
- Methodologists
- Other
- Patient/ support group representatives
- Researchers
- Service users
- COS for clinical trials or clinical research
- COS for practice
- Consensus meeting
- Delphi process
- Interview
- Literature review
- Systematic review
Systematic review of published studies and semistructured interviews with key stakeholders to inform the long list; international Delphi Consensus exercise; Consensus meeting to agree the final COS and reporting guidelines (Planned Sept 2024). The project will be overseen by an international steering group nominated by the BIG-NCTN.