Postoperative radiotherapy for Stage 1 endometrial carcinoma: long-term outcome of the randomized PORTEC trial with central pathology review.

Purpose: In 2000, the results of the multicenter Post Operative Radiation Therapy in Endometrial Carcinoma (PORTEC) trial were published. This trial included 714 Stage I endometrial carcinoma patients randomly assigned to postoperative pelvic radiotherapy (RT) or no further treatment, excluding those with Stage IC, Grade 3, or Stage IB, Grade 1 lesions. Radiotherapy significantly decreased the risk of locoregional recurrence (4% vs. 14%), without affecting overall survival. In this report the long-term outcome and results with central pathology review are presented.

Methods And Materials: The slides of 569 patients (80%) could be obtained for pathology review. Median follow-up for patients alive was 97 months. Analysis was done according to the intention-to-treat principle. The primary study endpoints were locoregional recurrence and death.

Results: Ten-year locoregional relapse rates were 5% (RT) and 14% (controls; p < 0.0001), and 10-year overall survival was 66% and 73%, respectively (p = 0.09). Endometrial cancer related death rates were 11% (RT) and 9% (controls; p = 0.47). Pathology review showed a substantial shift from Grade 2 to Grade 1, but no significant difference for Grade 3. When cases diagnosed at review as Grade 1 with superficial myometrial invasion were excluded from the analysis, the results remained essentially the same, with 10-year locoregional recurrence rates of 5% (RT) and 17% (controls; p < 0.0001).

Conclusions: In view of the significant locoregional control benefit, radiotherapy remains indicated in Stage I endometrial carcinoma patients with high-risk features for locoregional relapse.