To try to resolve the controversy over the value of radiotherapy for stage I endometrial cancer (ie, limited to the corpus), the Post Operative Radiation Therapy in Endometrial Carcinoma (PORTEC) study group from the Netherlands have conducted the largest randomised controlled trial yet addressing this issue. Included in this trial, the results of which are published in today’s Lancet, were 715 patients with well-differentiated (grade 1) carcinoma and deep invasion (> 50% of the myometrium), or moderately differentiated lesions (grade 2) that had invaded to any depth, or poorly differentiated cancer (grade 3) and superficial invasion (< 50% of the myometrium). External radiotherapy to the pelvis lowered the rate of local recurrence (4%, compared with 14% in the no-radiotherapy group) but did not influence overall survival. The complication rate was 6% in the control group, compared with 25% among the irradiated patients. Analysis of findings by risk factors led the investigators to recommend that postoperative radiotherapy is not indicated for patients aged under 60 years and those with superficial grade 2 disease.

The strengths of this trial include an a priori power calculation, excellent follow-up, intention-to-treat analysis, and detailed description of protocol violations. However, the findings should be examined in the context of other reports and to see what further questions are raised. PORTEC, like two other trials, 1, 2 could not prove that postoperative radiotherapy for endometrial cancer improves survival for their entire trial populations. Posthoc subset analyses were undertaken for each of these trials to try to identify which patients might benefit. These three trials differed in their features such as