The Prognostic Impact of Imaging Detected Tumor Deposits in Rectal Cancer: A Systematic Review and Meta-analysis

BACKGROUND: Tumor deposits (TDs) identified at pathology post rectal cancer resection are increasingly recognized as an adverse prognostic factor. Advances in magnetic resonance imaging (MRI) allow for the preoperative detection of TDs (mrTDs), raising the possibility that patients with mrTDs may benefit from neoadjuvant treatment strategies or enhanced surveillance. OBJECTIVE: This meta-analysis primarily aims to evaluate the prognostic significance of mrTDs in rectal cancer patients. We also evaluate the impact of other prognostic features. METHODS: A comprehensive search was conducted in MEDLINE, Embase, and Scopus databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Prognostic endpoints included disease-free survival (DFS) and overall survival (OS). Pooled hazard ratios (HR) were calculated using R software. RESULTS: Overall, 5813 and 5630 patients were included in the systematic review (13 studies) and meta-analysis (11 studies), respectively. The pooled HR for OS and DFS for mrTDs was 2.1 (95% confidence interval [CI] 1.63-2.70; p < 0.0001) and 2.13 (95% CI 1.68-2.71; p < 0.0001), respectively. The pooled HR for OS and DFS for extramural venous invasion (mrEMVI) and circumferential resection margin (mrCRM) involvement was also significantly increased (p < 0.01). The pooled HR for MRI-predicted nodal disease (mrLNMs) and T stage (mrT) for OS and DFS was insignificant (p > 0.05). CONCLUSION: This meta-analysis confirms the prognostic significance of mrTDs on OS and DFS in rectal cancer. This was also observed for mrEMVI and mrCRM, but not for mrLNMs or mrT. Current staging using TNM has poor prognostic power. A novel evidence-based staging system is needed to identify high risk patients and guide preoperative treatment strategies. Trial registration The protocol for this study was registered in the PROSPERO database (CRD420251011285).