A Cochrane review included 13 studies with a total of 2 362 subjects. Ten trials (2 122 patients) were included in a meta-analysis for the primary outcome. There was some evidence that preoperative chemotherapy improves survival (HR 0.88; 95% CI 0.80 to 0.96) and is associated with a significantly higher rate of complete (R0) resection (RR 1.11, 95% CI 1.03 to 1.19). There was no evidence that the overall rate of resections (RR 0.96, 95% CI 0.92 to 1.01), tumour recurrence (RR 0.81, 95% CI 0.54 to 1.22) or non-fatal complication rates (RR 0.90; 95% CI 0.76 to 1.06) differ for preoperative chemotherapy compared to surgery alone. Trials reported risks of toxicity with chemotherapy that ranged from 11% to 90%.
Comment: The quality of evidence is downgraded by inconsistency (variability in results across studies) and by indirectness (differences in studied patients).