ESTRO 2024 - Abstract Book

S1123

Clinical - Gynaecology

ESTRO 2024

model. Competing risk methods were used for progression-free survival and recurrence. PORTEC-3 is registered at ClinicalTrials.gov (NCT00411138).

Results:

At a median follow-up of 9.7 years, 10-year overall survival was 74.9% (95% CI 70.0 – 80.2) with chemoradiotherapy versus 66.6% (95% CI 61.3 – 72.6) with radiotherapy alone (adjusted HR 0.73 [95% CI 0.54 – 0.98], p = 0.039). For women with stage III disease, 10-year overall survival was 70.2% (95% CI 62.7 – 78.2) versus 56.0% (95% CI 47.4 – 66.2; adjusted HR 0.64 [95% CI 0.43 – 0.97], p = 0.035), respectively. Ten-year overall survival rates according to molecular subgroup were for p53abn 41.9% (95% CI 32.3 – 54.4), POLE mut 98.0% (95% CI 94.3 – 100), MMRd 72.3% (95% CI 63.9 – 81.7), and NSMP 78.1% (95% CI 70.1 – 87.1, p < .001). The 10-year overall survival with chemoradiotherapy versus radiotherapy per molecular subgroup was for p53abn 47.9% (95% CI 34.9 – 65.6) versus 35.2% (95% CI 22.8 – 54.3, p = 0.2); for POLE mut 100% versus 96.4% (95% CI 90 – 100, p = 0.4); for MMRd 68.2% (95% CI 56.1 – 83.0) versus 75.9% (95% CI 65.1 – 88.5, p = 0.3; and for NSMP 83.6% (95% CI 73.9 – 94.6) versus 71.6% (95% CI 59.2 – 86.6, p = 0.1). For the few patients with NSMP oestrogen receptor negative tumours ( N = 6 and N = 7, respectively), 10-year overall survival was 83% (95% CI 58.3-100%) with chemoradiotherapy versus 0% with radiotherapy alone. Ten-year progression-free survival was 67.1% (95% CI 61.7 - 72.4) with chemoradiotherapy versus 61.2% (95% CI 55.6 – 66.1) with radiotherapy alone (adjusted HR 0.76 [95% CI 0.58 – 1.01], p = 0.055). The cumulative incidence of distant recurrence was 22.8% (95% CI 18.7 – 27.8) at 5 years and 26.9% (95% CI 22.3-32.2) at 10 years after chemoradiotherapy versus 29.2% (95% CI 24.6-34.5) at 5 years and 31.1% (26.4 – 36.5) at 10 years after radiotherapy alone.

Conclusion:

The 10-year analysis of the PORTEC-3 trial confirmed improved overall survival with chemoradiotherapy versus radiotherapy alone for women with high-risk endometrial cancer. With extended follow-up, absolute overall