Five studies were included in the review (n=1,098 patients): one RCT and four retrospective cohort studies. Study sample size ranged from 112 to 517 patients. The authors reported that Cohort studies averaged 8 out of 9 on the Newcastle-Ottawa scale and the RCT scored 19 out of 21 on the Detsky scale.
Using a fixed-effects model, the risk of local recurrence was statistically significantly lower in the pre-operative radiotherapy group compared with the postoperative group (OR 0.61, 95% CI 0.42 to 0.89). However, when a random-effects model was used, the results were no longer statistically significant (OR 0.67, 95% CI 0.39 to 1.15). Average survival rate was 76% (range 62% to 88%) in the pre-operative radiotherapy group and 67% (range 41% to 83%) in the postoperative group.
There was evidence of moderate statistical heterogeneity (I2=25%). There was evidence of publication bias.