Abstract 22P
Background
Young early breast cancer (YEBC) patients (pts) defined as ≤40 years old (yo) have poor survival outcomes compared to older patients, especially in HR+ disease. Several clinical factors have been attributed to these differences, yet an increased incidence of aggressive subtypes suggests a unique biology. Thus, identifying clinical and genomic biomarkers can help tailor treatment strategies.
Methods
A registry-based study was conducted including pts ≤ 50yo with HR+/HER2- EBC treated in Hospital Clinic Barcelona (2016 to 2023) with PAM50/PROSIGNA data. Pts had baseline clinicopathological records (age, stage, Ki67, intrinsic subtype [IS], recurrence risk score [ROR] and treatment. Univariate and multivariate analysis to evaluate the association between clinic-pathological variables and survival was done using cox proportional hazards. The Kaplan-Meier method using the log-rank test was used for survival analysis.
Results
Among 274 pts, 68 (24.8%) were YEBC. Compared to 40-50yo pts (OEBC), YEBC had significantly higher nodal burden, N1-2 46.7% vs 30.3%, p=0.023, and baseline Ki67, median 19.5% vs 13 .0%, p<0.01. Regarding IS, YEBC were diagnosed with more non-luminal tumors than OEBC (20.9% vs 5.2%, p<0.01). Additionally, 32.4% and 53.3% of YEBC pts were defined as ROR-high in node negative and positive disease, compared to 19.1% and 35.0% in OEBC (p<0.01). As for treatment, 85% of YEBC received CT and 56.8% ovarian function suppression vs 28.5% and 20.4% in OEBC, respectively (p<0.001). With a median follow-up of 45 months, the unadjusted 5-year disease free survival (DFS) rates for YEBC pts versus OEBC pts were 76.9% and 93.4%, respectively (Hazard Ratio=2.92, p=0.037). Yet, in the multivariate cox model age was not significant, while only IS non-luminal tumors (HR=4.05; p=0.017) and tumor size (HR=3.54; p=0.018) were significantly associated to recurrence.
Conclusions
Young women with early breast cancer (YEBC) face more aggressive tumors and, despite receiving intensified treatments, still experience poorer outcomes compared to older premenopausal women. The primary determinant of prognosis appears to be tumor biology and stage rather than patient age.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.