A Cochrane review (abstract , review ) included 8 studies with a total of 1770 subjects. Seven trials compared pelvic external beam radiotherapy EBRT with no EBRT (or vaginal intracavity brachytherapy [VBT]), and 1 trial compared VBTwith no additional treatment. The addition of pelvic external beam radiotherapy (EBRT with or without VBT) to surgery reduced locoregional recurrence (time-to-event data: HR 0.36, 95% CI 0.25 to 0.52; 5 trials, n=2965; and dichotomous data: RR 0.33, 95% CI 0.23 to 0.47; 7 trials, n=3628). There was no reduction in overall survival (time-to-event data: HR 0.99, 95% CI 0.82 to1.20; 5 trials, n=2965, and dichotomous data: RR 0.98, 95% CI 0.83 to 1.15; 7 trials, n=3628) or endometrial cancer related survival (time-to-event data: HR 0.96, 95% CI 0.72 to 1.28; 5 trials, n=2965; and dichotomous data: RR 1.02, 95% CI 0.81 to 1.29; 7 trials, n=3628) or improved distant recurrence rates (dichotomous data: RR 1.04, 95% CI 0.80 to1.357 trials, n=3628). A subgroup analysis of women with multiple high risk factors (including stage 1c and grade 3) showed a trend toward the reduction in the risk of death from all causes and endometrial cancer death.
Comment: The quality of evidence is downgraded by sparse data. The authors conclude that external beam radiotherapy carries an inherent risk of damage and toxicity and should be avoided in stage I endometrial cancer patients with no high risk factors.