Co-enrolment of participants into multiple cancer trials: The Add-Aspirin trial experience


Session type:


Fay Cafferty1,Sam Rowley1,Christopher Coyle1,Lindy Berkman2,Mairead MacKensie3,Ruth Langley1
1MRC Clinical Trials Unit at UCL,2NCRI Consumer Forum,3Independent Cancer Patient Voices



Opportunities to enter patients into more than one clinical trial are not routinely considered in cancer research and experiences with co-enrolment are rarely reported. Benefits of allowing appropriate co-enrolment have been identified in other settings but there is a lack of evidence-base to inform this in oncology.


Add-Aspirin is a large, multicentre trial investigating use of aspirin for preventing recurrence and improving survival following primary treatment for an early stage cancer (breast, colorectal, prostate or gastro-oesophageal). Opportunities to co-enrol patients have been pro-actively explored. Here, we discuss benefits and challenges to this approach and propose measures for managing co-enrolment.


The potential for co-enrolment has been agreed with 41 other trials across the four tumour types. To date, 118 of 2040 (6%) participants entering Add-Aspirin were enrolled in another trial.

Potential benefits of co-enrolment include: improving recruitment feasibility; increased opportunities for patients to participate in trials; and collection of robust data on treatment combinations. The latter will ensure the ongoing relevance of individual trials and provide more cohesive evidence to guide management of future patients.

Perceived barriers to co-enrolment include scientific, safety and ethical issues. These warrant consideration on a trial-by-trial basis. In many cases any potential impact on the trial results is negligible – limited by a number of factors, including the overlap in trial cohorts.

Patient representatives stress the importance of autonomy to decide about trial participation, providing a compelling argument for offering co-enrolment where appropriate. Ensuring acceptability to (potential) participants is paramount.


Opportunities to enter patients into more than one trial should be considered more routinely. Where planned and managed appropriately, co-enrolment can offer a number of benefits in terms of both scientific value and efficiency of study conduct, and will increase the opportunities for patients to participate in, and benefit from, clinical research.