(Endometrial Cancer) Chemoradiotherapy vs. Radiotherapy Alone: PORTEC-3 Phase 3 Trial Results

• September 23, 2019
• 2 min read

On July 10, 2019, Stephanie M. de Boer published results in The Lancet Oncology from the PORTEC-3 Phase 3 clinical trial comparing the efficacy and safety of radiotherapy alone versus combined chemoradiotherapy in high-risk endometrial cancer patients.

Trial Design:

The PORTEC-3 trial enrolled high-risk endometrial cancer patients (N=660) in a 1:1 randomized Phase 3 design. Primary endpoints were 5-year overall survival (OS) and 5-year progression-free survival (PFS).

• Radiotherapy group (N=330): 48.6 Gy radiation
• Chemoradiotherapy group (N=330): Cisplatin 50 mg/m² + radiotherapy (48.6 Gy), followed by carboplatin + paclitaxel 175 mg/m²

Results at median follow-up of 72.6 months:

Primary endpoints:

• 5-year OS: Radiotherapy 76.1% vs. chemoradiotherapy 81.4%
  • 30% reduction in disease progression or death risk (HR: 0.70)
• 5-year PFS: Radiotherapy 69.1% vs. chemoradiotherapy 76.5%
  • 30% reduction in disease progression or death risk (HR: 0.70)

Secondary endpoint:

• 5-year distant metastasis rate: Radiotherapy 29.1% vs. chemoradiotherapy 21.4%
  • 26% reduction in distant metastasis risk (HR: 0.74)

Safety:

Grade 3+ adverse events: Radiotherapy 5% vs. chemoradiotherapy 8% — no significant difference between groups. Grade 3+ hypertension: 2% in both groups. At 5 years from treatment initiation, Grade 2+ adverse events: Radiotherapy 23% vs. chemoradiotherapy 38%.

Conclusion: Based on the PORTEC-3 trial results, Stephanie M. de Boer concluded that combined chemoradiotherapy significantly improved 5-year OS and 5-year PFS compared to radiotherapy alone in high-risk endometrial cancer patients.

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Source: Adjuvant chemoradiotherapy versus radiotherapy alone in women with high-risk endometrial cancer (PORTEC-3): patterns of recurrence and post-hoc survival analysis of a randomised phase 3 trial. Lancet Oncol. 2019 Jul 22. doi:10.1016/S1470-2045(19)30395-X

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