Background
Retrospective cohort study, N=1474 (224 extended therapy, 1250 stopped after 5 years), ER+/HER2- breast cancer disease-free after 5 years of adjuvant endocrine therapy. High-risk defined as lymph-node positivity, tumor size >2 cm, or high grade. Evaluates the benefit of continuing endocrine therapy beyond 5 years.
Interventions and follow up
Arm A: Extended endocrine therapy (duration not specified, continued beyond 5 years)
Arm B: Stopped endocrine therapy after standard 5 years
Primary endpoint: Disease-free survival (DFS)
mFollow up: 10 years
Arm B: Stopped endocrine therapy after standard 5 years
Primary endpoint: Disease-free survival (DFS)
mFollow up: 10 years
Results
DFS (high-risk, N=348 post-matching): significantly higher in extended-therapy group; 69% reduction in recurrence risk, HR 0.31 (implied)
Distant DFS: also improved with extended therapy
Distant DFS: also improved with extended therapy
Adverse events
Gynecologic (tamoxifen-related): vaginal bleeding and endometrial cancer are recognized risks; rates NR in this retrospective analysis
Skeletal (aromatase-inhibitor-related): osteoporosis/bone loss a known risk of extended AI therapy; not detailed in the dataset
Skeletal (aromatase-inhibitor-related): osteoporosis/bone loss a known risk of extended AI therapy; not detailed in the dataset
Conclusions
Extended endocrine therapy substantially improves DFS in high-risk ER+/HER2- early breast cancer, especially in patients with large tumors, node involvement, and high grade. Supports personalized long-term therapy strategies for high-risk patients.
Key Limitations
Retrospective design with selection bias; propensity-score matching may not eliminate unmeasured confounders; extended-therapy duration/type not specified; heterogeneous endocrine agents; patient choice/tolerance influenced treatment assignment; no quality-of-life data.
Clinical Context
Aligns with ASCO and ESMO guidance supporting consideration of extended endocrine therapy (beyond 5 years, typically to 7–10 years) in node-positive and high-grade ER+/HER2- early breast cancer. The benefit must be weighed against cumulative toxicity, and these retrospective data inform individualized risk-benefit discussions rather than mandate practice. ESMO-MCBS: not applicable (retrospective cohort).