Subgroup analysis comparing overall survival in intermediate- and high-risk patients demonstrated no improvement with external-beam radiotherapy. Nor was overall survival altered by lymphadenectomy. The authors performed a meta-analysis using data from GOG99, PORTEC1, and this combined trial, and found no significant difference in overall survival or disease-specific survival, regardless of histologic risk group.
Trial has notable strengths and weaknesses
This large prospective trial has significant strengths: its size and its multi-institutional nature. The authors also evaluated their data in combination with other randomized, controlled trials to further investigate the effect of external-beam radiotherapy on survival. However, allowing brachytherapy somewhat confounds the true effect of external-beam radiotherapy on local recurrence. (There were few local recurrences, and the authors did not evaluate whether women who had an isolated vaginal recurrence received vaginal brachytherapy.) Moreover, 15% of women who were randomized to external-beam radiotherapy did not complete it.
In addition, secondary randomization of patients in the intermediate-risk and high-risk categories to external-beam radiotherapy versus no treatment may have significantly confounded the results of the entire ASTEC trial. Because women were, or were not, randomized to treatment regardless of node status, some patients who had positive nodes failed to receive adjuvant treatment. This may have had a significant effect on overall survival, as positive lymph nodes are a negative prognostic factor.