Walther A et al. (2008) Association between chromosomal instability and prognosis in colorectal cancer: a meta-analysis. Gut 57: 941–950

Despite advances in treatment, colorectal cancer remains a major cause of mortality in the developed world; therefore, it is important to identify patients who will benefit most from treatment. Studies have shown that microsatellite instability is of prognostic importance for patients with colorectal cancer. Recent data, however, have suggested that microsatellite instability could be secondary to the effects of chromosomal instability. Walther et al. conducted a systematic review of all published studies on chromosomal instability in patients with colorectal cancer to investigate the prognostic significance of this abnormality.

The authors used PubMed and EmBase to identify 63 studies that stratified survival by chromosomal instability status in patients with colorectal cancer. The main outcome measure was hazard ratio (HR) for death. Of the 10,126 patients included in this analysis, 60% had chromosomal instability. Chromosomal instability was significantly associated with an increased risk of death in patients with colorectal cancer of all stages (HR 1.45, 95% CI 1.35–1.55; P <0.001) and in patients with stage II–III colorectal cancer who were candidates for adjuvant chemotherapy (HR 1.45, 95% CI 1.27–1.65; P <0.001). Progression-free survival was similarly affected by chromosomal instability status (HR 1.71, 95% CI 1.51–1.94; P <0.001).

Walther and colleagues conclude that chromosomal instability is associated with a worse prognosis in patients with colorectal cancer and could be of value as a prognostic marker, along with microsatellite instability. Clinical trials are needed to investigate the contribution of each type of genomic instability to prognosis.