Interim results from the EUROPA trial suggest that radiotherapy (RT) better preserves health-related quality of life (HRQoL) compared to endocrine therapy (ET) as single-modality treatments in older women with low-risk early-stage breast cancer following breast-conserving surgery. However, further data on disease control outcomes are needed before definitive conclusions can be made.
A high prevalence of oestrogen receptor (ER)-positive stage I breast cancer is observed in women aged ≥70 years. It is crucial to reduce treatment burden and to balance treatment efficacy with HRQoL. However, optimal therapy following breast-conserving surgery in older adults with low-risk, early-stage breast cancer remains uncertain. The EUROPA trial aimed to compare the effects of RT and ET as single-modality treatments on HRQoL and ipsilateral breast tumour recurrence outcomes in this population. The preplanned interim analysis of the EUROPA trial was presented at SABCS 2024 and simultaneously fully published.1,2
Study design
The multi-centre, non-inferiority, phase III EUROPA trial enrolled elderly women (≥70 years) who underwent breast-conserving surgery and had histologically confirmed stage I luminal A-like breast cancer (pT1 pN0 (or cN0), ER/PgR ≥10%, Ki67 ≤20%, and HER2-negative). Patients were randomised (1:1) to single-modality ET (daily oral aromatase inhibitors or tamoxifen, for a total planned duration of 5-10 years) or RT (whole breast or partial breast irradiation, delivered in 5-15 fractions). The coprimary endpoints were 5-year rates of ipsilateral breast tumour recurrence and 2-year HRQoL outcomes (assessed by the global health status [GHS] scale of the EORTC QLQ-C30 questionnaire). This preplanned interim analysis was performed once at least 152 patients completed the 24-month GHS HRQoL assessment. The study is still ongoing and actively recruiting.
Results
Of the 207 patients included in this preplanned interim analysis, 74% were aged 70-79 years and 60% had a geriatric score (G8) above fourteen. Median follow-up was 23.9 months. The mean baseline GHS score was 71.9 in the RT group and 75.5 in the ET group. At 24 months, the age/G8-adjusted mean change from baseline in GHS was -3.40 (p= 0.13) in the RT group and -9.79 (p< 0.0001) in the ET group, with an adjusted mean difference of 6.39 (p= 0.045) favouring RT. In addition, the RT arm showed better outcomes compared to the ET arm for most functional domains (including physical, emotional, cognitive and social functioning) and symptom domains (including fatigue, nausea/vomiting, pain, dyspnoea, insomnia, and appetite loss) of the QLQ-C30 questionnaire. In both arms, ipsilateral breast tumour recurrences or locoregional relapses were absent. Treatment-related adverse events were less frequent in the RT group (67.0%) compared to the ET group (85.4%). At 24 months, 22.5% of patients in the ET arm switched to an alternative ET and 12.4% permanently discontinued ET.
Conclusion
Results of this preplanned interim analysis showed better preserved HRQoL with single-modality RT compared to single-modality ET at 24 months, with a lower incidence of treatment-related adverse events in the RT arm. These results should be interpreted with caution and longer follow-up is needed to draw definitive conclusions.
References
1. Meattini I, et al. Exclusive endocrine therapy or radiation therapy in women aged 70+ years with luminal-like early breast cancer (EUROPA): preplanned interim analysis of a randomized phase 3 trial. Presented at SABCS 2024; Abstract GS2-01.
2. Meattini I, et al. Single-modality endocrine therapy versus radiotherapy after breast-conserving surgery in women aged 70 years and older with luminal A-like early breast cancer (EUROPA): a preplanned interim analysis of a phase 3, non-inferiority, randomised trial. Lancet Oncol 2024;doi:10.1016/S1470-2045(24)00661-2.
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