Developing a Core Outcome Set for Cytoreductive Surgery for Colorectal Cancer with Peritoneal Metastases: A Mixed-Method Study Protocol

As the number of centres offering cytoreductive surgery (CRS) for colorectal cancer with peritoneal metastases (CPMs) is increasing worldwide, research is focused on establishing better patient selection and ensuring that new techniques have positive impacts on survival. However, high-impact comparative research in this field is limited by the heterogeneity of outcome measurement and reporting. Additionally, as there are comparatively few randomised controlled trials reporting comprehensive patient-reported outcomes, it is possible that key stakeholders such as patients and carers are underrepresented in the current literature. A core outcome set (COS) for CRS with or without intraperitoneal chemotherapy for the treatment of CPMs, supported by clinicians and patients, will promote homogenous comparison across trials and optimise the utility of research findings. We have established a comprehensive protocol based on the Core Outcome Measures in Effectiveness Trials (COMETs) method to facilitate this. A systematic review will identify all the outcomes reported in the literature, whereas a semi-structured interview will identify outcomes considered important by patients and carers. The identified outcomes will populate an international Delhi survey, distributed to patients, carers, surgeons, oncologists, nurses, and allied health clinicians. Outcomes reaching international consensus of importance will be further discussed in a face-to-face workshop between patients, carers, and clinicians. This process will inform the development of a final COS for CRS for patients with CPMs.