Prognostic impact of myosteatosis on postoperative outcomes and survival in colorectal cancer: a systematic review.

PURPOSE: To characterise (1) the definition and measurement methods of myosteatosis, (2) the impact of myosteatosis on post-operative complications (overall, severe complications defined as Clavien-Dindo 3 and above, anastomotic leak, length of stay) in both non-metastatic and metastatic colorectal cancer (CRC) patients and (3) the impact of myosteatosis on long-term survival outcomes in non-metastatic CRC (overall survival, cancer-specific survival, disease-free survival). METHODS: A systematic search of Medline, Embase and Cochrane Central databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in 2024. RESULTS: A total of 4410 publications were initially retrieved; 54 studies fulfilled the inclusion criteria. A variety of measurement methods of myosteatosis were found. There was good quality evidence to support a negative correlation between myosteatosis and overall survival (OS). Colon cancer was more consistently associated with OS and DFS compared to rectal cancer. Myosteatosis was found to significantly impact severe (Clavien-Dindo 3 and above) postoperative complications in colon cancer. Other postoperative outcomes were limited by inconsistency and an overall paucity in volume and quality. CONCLUSION: Myosteatosis has a negative association with OS, with consistent effects observed in colon cancer. There is a negative association with severe postoperative outcomes, particularly in colon cancer. These results are limited by the risk of bias and heterogeneity in measurement methods and statistical analysis. Future work is required to clarify the scan acquisition protocol and diagnostic criteria.