Introduction
The traditional double blind RCT is the ‘gold standard’ trial design. For a variety of reasons, these designs often fail to accrue enough participants to conclude. This is particularly challenging in localized prostate cancer. The cohort multiple randomised controlled trial (cmRCT) trial design may represent an alternative approach to delivering robust comparative data in prostate cancer.

Patients and methods
IP3-PROSPECT is a cmRCT designed to test multiple prostate cancer interventions from eligible men in one cohort. Key to the design is two points of consent. First, at point of consent one, men referred for prostate cancer investigations are invited to join the cohort. They may then be randomly invited at a later date to consider an intervention at point of consent two. In the pilot phase we will test the acceptability and feasibility of developing the cohort.

Results
Acceptability and feasibility of the study will be measured by a combination of quantitative and qualitative methods. The primary outcome measure is the rate of consent to inclusion to the IP3-PROSPECT cohort. Secondary outcome measures include the completeness of data collection at sites and return rates of patient questionnaires. We will also interview patients and healthcare professionals to explore their thoughts on the implementation, practicality and efficiency of IP3-PROSPECT.

Conclusion
The IP3-PROSPECT study will evaluate the cmRCT design in prostate cancer. Initially we will pilot the design, assessing for acceptability and feasibility. The cmRCT is an innovative design that offers potential for building a modern comparative evidence base for prostate cancer.