Background
Phase III RCT (PORTEC-1). 715 patients with stage I endometrial carcinoma (grade 1 with >50% myometrial invasion; grade 2 with any invasion; grade 3 with ≤50% invasion) after total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH-BSO) without lymph node dissection. Randomized to pelvic external beam RT (EBRT) 46 Gy in 23 fractions vs no additional treatment. Trial designed to determine whether adjuvant pelvic RT reduces recurrence without improving OS. Long-term results published at 15 years (Nout JCO 2011).
Interventions and follow up
Arm A: Pelvic EBRT 46 Gy in 23 fractions (adjuvant)
Arm B: No adjuvant treatment (observation)
Primary endpoint: Locoregional recurrence
mFollow up: 13 years (long-term)
Arm B: No adjuvant treatment (observation)
Primary endpoint: Locoregional recurrence
mFollow up: 13 years (long-term)
Results
5-year locoregional recurrence: 4% (EBRT) vs 14% (observation), P<.001
5-year OS: 81% (EBRT) vs 85% (observation) — not significant
15-year locoregional recurrence: 6% (EBRT) vs 15% (observation), P<.001
15-year OS: 52% (EBRT) vs 60% (observation) — not significant (NS)
Vaginal recurrence: Dramatically reduced with EBRT (1% vs 7%)
5-year OS: 81% (EBRT) vs 85% (observation) — not significant
15-year locoregional recurrence: 6% (EBRT) vs 15% (observation), P<.001
15-year OS: 52% (EBRT) vs 60% (observation) — not significant (NS)
Vaginal recurrence: Dramatically reduced with EBRT (1% vs 7%)
Adverse events
Main adverse events: Grade 3–4 late bowel toxicity: 3% (EBRT) vs 0% (observation) at 5 years; increasing to 4% vs 1% at 15 years. Urinary toxicity increased over time in EBRT arm. EBRT significantly impaired quality of life (bowel dysfunction, urinary complaints) during and after treatment.
Conclusions
Pelvic EBRT significantly reduced locoregional recurrence in intermediate-risk stage I endometrial cancer but provided no OS benefit, and was associated with late bowel and urinary toxicity. These findings supported transitioning from pelvic EBRT to vaginal brachytherapy (VBT) for most intermediate-risk patients (PORTEC-2).
Key Limitations
Key Limitations: No lymph node dissection performed — some patients had occult nodal disease. No stratification by LVSI. Grade 3 with deep invasion patients (now considered high-risk) were included in a mixed risk population. Vaginal brachytherapy was not used in either arm — the relevant comparison (EBRT vs VBT) was addressed in PORTEC-2. Predates molecular classification of endometrial cancer.
Clinical Context
PORTEC-1 established that adjuvant pelvic EBRT reduces locoregional recurrence without improving OS in intermediate-risk endometrial cancer, and that the main site of recurrence (vagina) can be addressed more selectively with VBT. PORTEC-2 demonstrated VBT equivalence to EBRT with superior QoL. Current practice reserves pelvic EBRT for high-risk patients (stage III, high-grade) while using VBT for intermediate-risk.