A systematic review including 6 studies with a total of 738 patients was abstracted in DARE. NCRT plus surgery was associated with a slight improvement in overall survival compared with surgery alone. However, this was not statistically significant (RR of death 0.86, 95% CI: 0.74, 1.01, P=0.07). There was no evidence of statistical heterogeneity between the studies (P=0.41). A subgroup analysis of the four studies that only included patients with squamous cell carcinoma found no statistically significantly difference in overall survival (RR of death 0.94, 95% CI: 0.77, 1.13, P=0.5).
Comment: The quality of evidence is downgraded by imprecise results (few patients) and severe limitations in review methodology.