Survival Outcomes and Clinicopathological Features in Inflammatory Bowel Disease-associated Colorectal Cancer: A Systematic Review and Meta-analysis.

OBJECTIVE: The aim of our study was to conduct a systematic review and meta-analysis comparing the survival outcomes of IBD-associated and non-IBD-associated CRC. SUMMARY OF BACKGROUND DATA: Investigations comparing the prognosis in CRC patients with and without IBD have yielded conflicting results. METHODS: PubMed/MEDLINE, Embase, Web of Science, Cochrane Library were searched for studies evaluating the prognostic outcomes between CRC patients with IBD and those without IBD. Estimates of survival-related outcomes and clinicopathological features in IBD-CRC and non-IBD CRC were pooled through random-effects or fix-effects models. The study is registered with PROSPERO, CRD42021261513. RESULTS: Of 12,768 records identified, twenty-five studies with 8034 IBD-CRC and 810,526 non-IBD CRC patients were included in the analysis. IBD-CRC patients have a significant worse overall survival (OS) with the hazard ratio (HR) of 1.33 [95% confidence interval (CI): 1.20-1.47] than those without IBD. Pooled estimates of cancer-specific survival demonstrated that IBD-CRC patients had a poorer cancer-specific survival than those without IBD with fixed-effect model (HR, 2.17; 95% CI: 1.68-2.78; P < 0.0001). Moreover, ulcerative colitis-associated CRC patients have favorable OS than Crohn's disease-associated CRC (HR 0.79,95% CI: 0.72-0.87). Compared to non-IBD-CRC, patients with IBD-associated CRC are characterized by an increased rate of poor differentiation (OR 2.02, 95% CI: 1.57-2.61), mucinous or signet ring cell carcinoma (OR 2.43, 95% CI: 1.34-4.42), synchronous tumors (OR 3.18, 95% CI: 2.26-4.47), right-sided CRC (OR 1.62, 95%CI: 1.05-2.05), male patients (OR 1.10, 95% CI: 1.05-1.16), and a reduced rate of R0 resections (OR 0.60, 95% CI: 0.44-0.82). CONCLUSIONS: IBD-CRC patients have a significant worse OS than patients with non-IBD CRC, which may be attributed to more aggressive histological characteristics and a lower rate of R0 resections at the primary tumor site. Optimized therapeutic standards and tailored follow-up strategies might improve the prognosis of IBD-CRC patients.