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Post-operative avoidance of radiotherapy: biomarker selection of women categorised to be in a very low risk group by IHC4+C.


Disease site: Breast cancer

Treatment modality: Radiotherapy

Status: In follow-up


Trial details

PRIMETIME is a phase III, multicentre trial which tests whether radiotherapy can be safely avoided in patients considered to have such a low risk of local recurrence that the potential absolute gain from radiotherapy does not outweigh the established risks associated with breast radiotherapy.

PRIMETIME will use immunohistochemical biomarkers with clinical information (IHC4+C) to direct selective avoidance of breast radiotherapy. The IHC4+C algorithm will be used to risk stratify patients into a very low risk group (recommended avoidance of radiotherapy) or not (standard radiotherapy). 

Approximately 2,400 patients will be registered over four years to recruit 1,500 patients in the no radiotherapy group. All patients will be followed up for 10 years. 


Further information

Chief InvestigatorDr Charlotte Coles, The University of Cambridge

ICR-CTSU Scientific Lead: Professor Judith Bliss

Trial management contact:

ISRCTN: 41579286

Sponsor: The Institute of Cancer Research (ICR)

Funding: Cancer Research UK

View PRIMETIME on the National Institute for Health Research website: NIHR - Be Part Of Research and a plain English summary from Cancer Research UK.


PRIMETIME Study video

We have produced a video for patients who have been invited to take part in the PRIMETIME study. The video is supplemental to the PRIMETIME main study patient information sheets and decision aid diagrams provided to eligible patients by their study doctor or nurse. Please make sure that you have read the PRIMETIME main study patient information sheets and decision aid diagrams before you watch this video. The video is designed to build on the information you have already received from your doctor. Please contact your breast cancer team with any questions about the PRIMETIME study. 

What the PRIMETIME video at

Further information for potential participants

Patient Information Sheet

Further information for healthcare professionals



Publications and presentations

C.C. KirwanC.E. Coles, J. Bliss, On Behalf of the PRIMETIME Protocol Working Group; It's PRIMETIME. Postoperative Avoidance of Radiotherapy: Biomarker Selection of Women at Very Low Risk of Local Recurrence


Indrani S. Bhattacharya, Joanne S. Haviland, Lesley Turner, Hilary Stobart, Ada Balasopoulou, Liba Stones, Anna M. Kirby, Cliona C. Kirwan, Charlotte E. Coles & Judith M. Bliss on behalf of the PRIMETIME Trialists; Can patient decision aids reduce decisional conflict in a de-escalation of breast radiotherapy clinical trial? The PRIMETIME Study Within a Trial implemented using a cluster stepped-wedge trial design


PRIMETIME Newsletters

PRIMETIME Patient Newsletter June 2022

Clinical trials

Division of Clinical Studies

The division carries out or coordinates high-quality trials and translational research at both an early phase – typically to test new targeted drugs – and a later stage.