Introduction Prehabilitation aims to enhance patient fitness before surgery, reduce postoperative complications and improve recovery. However, recent prehabilitation trials lack consistency in reported outcomes and standardised definitions. This review outlines outcomes in RCTs which studied prehabilitation for cancer surgery patients. Method We searched Embase, AMED, The Cochrane Library, PsycINFO, MEDLINE, and CINAHL until July 2021. We included RCTs assessing preoperative interventions in adult oncology patients undergoing surgery. Outcomes reported in each article were extracted and categorised into standardised outcomes and domains. The quality of outcome reporting was assessed using Harman et al.'s tool, scoring from 0 to 6, where 0 indicated none of the criteria were addressed (1). Results We included 74 RCTs, extracting 601 outcomes which were merged into 119 standardised outcomes. Only 18.3% of outcomes were defined, 44.9% labelled as primary or secondary, and 32.9% measured with a validated tool. The quality score for outcome reporting was poor, with a median score of 2. The outcome reporting quality was low with a median score of 2. Surgical outcomes were the most reported domain (95.9%). Conclusion RCTs show considerable variation in outcome reporting and lack clear definitions for many outcomes. Implementing core outcome sets is essential to improve outcome reporting quality, aiding interpretation, and bolstering the evidence base for prehabilitation. 1. Harman NL, Bruce IA et al. MOMENT-Management of Otitis Media with Effusion in Cleft Palate: protocol for a systematic review of the literature and identification of a core outcome set using a Delphi survey. Trials. 2013;14:70