Fifteen-Year Radiotherapy Outcomes of the Randomized PORTEC-1 Trial for Endometrial Carcinoma

Purpose To evaluate the very long-term results of the randomized Post Operative Radiation Therapy in Endometrial Carcinoma (PORTEC)-1 trial for patients with Stage I endometrial carcinoma (EC), focusing on the role of prognostic factors for treatment selection and the long-term risk of second cancers. Patients and Methods The PORTEC trial (1990–1997) included 714 patients with Stage IC Grade 1–2 or Stage IB Grade 2–3 EC. After surgery, patients were randomly allocated to external-beam pelvic radiotherapy (EBRT) or no additional treatment (NAT). Analysis was by intention to treat. Results 426 patients were alive at the date of analysis. The median follow-up time was 13.3 years. The 15-year actuarial locoregional recurrence (LRR) rates were 6% for EBRT vs. 15.5% for NAT ( p < 0.0001). The 15-year overall survival was 52% vs. 60% ( p = 0.14), and the failure-free survival was 50% vs. 54% ( p = 0.94). For patients with high-intermediate risk criteria, the 15-year overall survival was 41% vs. 48% ( p = 0.51), and the 15-year EC-related death was 14% vs. 13%. Most LRR in the NAT group were vaginal recurrences (11.0% of 15.5%). The 15-year rates of distant metastases were 9% vs. 7% ( p = 0.25). Second primary cancers had been diagnosed over 15 years in 19% of all patients, 22% vs. 16% for EBRT vs. NAT ( p = 0.10), with observed vs. expected ratios of 1.6 (EBRT) and 1.2 (NAT) compared with a matched population ( p = NS). Multivariate analysis confirmed the prognostic significance of Grade 3 for LRR (hazard ratio [HR] 3.4, p = 0.0003) and for EC death (HR 7.3, p < 0.0001), of age >60 (HR 3.9, p = 0.002 for LRR and 2.7, p = 0.01 for EC death) and myometrial invasion >50% (HR 1.9, p = 0.03 and HR 1.9, p = 0.02). Conclusions The 15-year outcomes of PORTEC-1 confirm the relevance of HIR criteria for treatment selection, and a trend for long-term risk of second cancers. EBRT should be avoided in patients with low- and intermediate-risk EC.