GOG 99.

Methods	A balanced block randomisation scheme was used. 448 women randomised; 56 women were excluded from the ITT analysis on the basis that they were ineligible either because of inadequate staging or because of histology or FIGO stage.
Participants	Women with Stage IB and IC, also IIA (occult) and IIB (occult) and had TAH and BSO and selective bilateral pelvic, and para‐aortic lymphadenectomy with removal of any enlarged or suspicious nodes.
Interventions	Women were randomised to either whole pelvic RT (190 women) or no additional therapy (202 women). Median follow‐up was 56 months with 9% followed for less than 2 years.
Outcomes	Pelvic RT reduced pelvic and vaginal recurrences but not the overall survival as pelvic recurrences are often effectively treated with second‐line therapy.
Notes	A high intermediate risk group (HIR) was defined as those with (1) moderate to poorly differentiated tumour, presence of lymphovascular invasion, and outer third myometrial invasion; (2) age 50 or greater with any two risk factors listed above; or (3) age of at least 70 with any risk factor listed above. RT had greatest impact on preventing recurrence in this subgroup. Statistically significant differences were seen in frequency and severity of haematological, GI, GU and cutaneous toxicities in favour of the control group (P < 0.001).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A balanced block randomisation scheme was used.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition. EBRT group size smaller than control group but post‐randomisation exclusions were made without knowledge of outcome data.
Selective reporting (reporting bias)	Low risk	All expected outcomes reported. Analysis by ITT.
Other bias	Low risk	High quality trial.