Objective: To clarify the effect of postoperative (adjuvant) external-beam pelvic radiotherapy (EBRT) for different grades of early endometrial cancer.
Search strategy: Meta-analysis of data from randomised trials stratified by histological risk factors supported by cohort studies.
Selection criteria: Cochrane methodology.
Data: Seven randomised trials were identified. Five were eligible for meta-analysis. Homogeneity was confirmed (I2 < 25%).
Main outcome measures: Survival, site of recurrence and added complications.
Main results: EBRT after hysterectomy for low-risk disease increases the odds of death (OR for overall survival 0.71; 95% CI 0.52-0.96). EBRT does not appear to alter survival for intermediate-risk cancers (stage ICG1/2 and IBG3) (OR 0.97; 95% CI 0.69-1.35). In contrast, EBRT offers a significant disease-free survival advantage for high-risk cancer (OR 1.76; 95% CI 1.07-2.89). The survival advantage benefits one in ten women. The definition of high risk is variable across studies but focuses on ICG3 (deeply invasive, poorly differentiated) tumours. Pelvic EBRT reduces the risk of pelvic recurrent disease in all types of invasive endometrial cancer (OR 0.27; 95% CI 0.16-0.44), but local recurrence may respond to salvage treatment. The risk of distant metastasis appears to be increased significantly by prophylactic EBRT (OR 1.58; 95% CI 1.07-2.35), but this might be because pelvic relapse in untreated women alters reporting of metastatic disease.
Authors' conclusions: Adjuvant EBRT should not be used for low- (IA, IBG1) or intermediate-risk (IBG2) cancer, but it is associated with a 10% survival advantage for high-risk (stage ICG3) endometrial cancer. This challenges the role of a staging lymphadenectomy.