PRECEDENT: imProving REporting of loCoregional therapies in nEoaDjuvant brEast caNcer Trials

Neoadjuvant 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.


Co-leads: Shelley Potter, University of Bristol and Stuart McIntosh, Queens University Belfast
Kerry Avery, University of Bristol
Katherine Cowan, Independent Facilitator
Jana de Boniface, Karolinska Instituet, Sweden
Peter Dubsky, University of Lucerne, Switzerland
David Dodwell, University of Oxford, UK
Mairead McKenzie, Independent Cancer Patients’ Voice, UK
Andrea Richardson, Johns Hopkins Medicine, USA
Karla Sepulveda, Baylor College of Medicine, USA
Gustavo Weretsky, Latin American Cooperative Oncology Group, Porto Alegre, Brazil
Jean Wright, Johns Hopkins Medicine, USA
On behalf of the Breast International Group (BIG) and the National Institute for Health (NIH) National Clinical Trials Network (NCTN)

Further Study Information

Current Stage: Ongoing
Date: August 2023 - December 2024
Funding source(s): TBC

Health Area

Disease Category: Cancer

Disease Name: Breast cancer

Target Population

Age Range: 16 - 120

Sex: Female

Nature of Intervention: Other

Stakeholders Involved

- Clinical experts
- Methodologists
- Other
- Patient/ support group representatives
- Researchers
- Service users

Study Type

- 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.

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