Fourteen retrospective studies were identified (2,204 participants, range 36 to 610, were reported in Table 1). There were no randomised controlled trials (RCTs). Nine studies scored at least 8 for quality and five studies scored 6 or 7.
Operative outcomes (13 studies): There were no significant differences for operative time (nine studies) and blood loss (five studies). Postoperative stay was significantly shorter for simultaneous versus staged resection (WMD -4.77 days, 95% CI -7.26 to -2.28, Ι²=96.4%; 12 studies). All these meta-analyses had significant heterogeneity.
Morbidity (14 studies): There were significantly lower levels of morbidity for simultaneous versus staged resection (OR 0.71, 95% CI 0.57 to 0.88, Ι²=10.5%; 14 studies). The funnel plot for morbidity showed no evidence of publication bias.
Overall Survival (11 studies): There were no significant differences in overall survival for simultaneous versus staged resection at one year (OR 0.77, 95% CI 0.51 to 1.16; 11 studies), three years (OR 1.12, 95% CI 0.85 to 1.47; 10 studies) and five years (OR 1.14, 95% CI 0.86 to 1.50; 10 studies). There was no significant heterogeneity at any time point.