A systematic review and meta-analysis of the relationship between chromosome 18q genotype, DCC status and colorectal cancer prognosis.

Results from studies investigating the relationship between colorectal cancer survival and chromosome 18q allelic imbalance (AI)/loss of DCC expression (LOE) have been inconsistent. We have reviewed and pooled published studies to estimate the prognostic significance of chromosome 18q status more precisely. Data from 27 studies were eligible. Survival data were pooled using standard meta-analysis techniques. Considerable variation between assessment method, marker choice, and threshold for assigning AI/LOE was observed. Pooling data from a 2189 cases from 17 studies showed significantly worse overall survival in patients with AI/LOE (HR = 2.00, 95%CI: 1.49-2.69), maintained both in the adjuvant setting (HR = 1.69, 95%CI:1.13-2.54), and also by method (HR = 1.67, 95%CI: 1.19-2.36, genotyping microsatellites; HR = 3.00, 95%CI: 1.98-4.56, immunohistochemistry). There was however evidence of heterogeneity and publication bias. Cancers with chromosome 18q loss appear to have a poorer prognosis. Prospective studies using consistent methodology are needed to precisely quantify its effect and role in patients with stage II-III disease.