Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Among the common malignant tumors in men worldwide, the incidence of prostate cancer (PCa) ranks second only to lung cancer, which will bring an economic burden to patients and their families and reduce the quality of life of patients. Researchers have conducted numerous clinical trials on the efficacy and safety of different interventions in the treatment of prostate cancer with traditional Chinese medicine combined with standard treatment regimens. However, published clinical trials currently suffer from inconsistent and irregular reporting of outcome measures. Objective: To facilitate future research in prostate cancer, a core outcome set (COS) is needed, which helps the trials into high-quality evidence. Methods: This mixed-method project has three phases instrument: 1. A scoping review of the literature to identify outcomes that have been reported in clinical trials and systematic reviews of clinical trials of interventions for PCa in the treatment of TCM. And a ualitative component using interviews to obtain the views of PCa patients, families, and their caregivers (with the history of TCM treatment). 2. Delphi survey among stakeholders to prioritize the core outcomes. Participants will include Traditional Chinese and Western medicine clinicians in prostate cancer-related directions, nurses, and methodology experts participated in two rounds of Delphi method expert consultation to score each outcome in the list of outcome indicators. 3. A face-to-face consensus meeting to discuss and agree on the final PCa in the treatment of TCM COS. Results: The protocol has been registered in PROSPERO and we will initiate the review on June 1st, 2023, and results should be expected by September 1st, 2023. And the Delphi survey among stakeholders is also expected to start in June 2023. Conclusions: The development of a core outcome set for assessing clinical safety outcomes of prostate cancer in clinical trials of Traditional Chinese medicine will provide a significant first step to assist the Chinese doctors, researchers and policy makers. Clinical Trial: Core Outcome Measures in Effectiveness Trials (COMET) Initiative database registration: https://www.comet-initiative.org/Studies/Details/2012. This study protocol was registered in the PROSPERO database before the start of the review process (CRD42022356184). The Ethical approval of this study has been granted by the First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Research Ethics Committee (TYLL2022[K]-21).