256P - Evolution and risk stratification of adjuvant treatment strategies for early breast cancer: A Chinese perspective based on a national cancer database

Background

HR+, HER2- early breast cancer (EBC) patients (pts) with high-risk clinicopathologic features (CPF) are at increased risk of early recurrence. This is the first study aimed at investigating the evolving adjuvant therapy landscape.

Methods

The study cohort, based on the medical records from 50 major hospitals across China linked with China Vital Registration (death information), included pts with HR+, HER2- stage I-III EBC who received surgery and adjuvant endocrine therapy (AET) from Jan 1, 2013, to Mar 31, 2021. CPF were used to identify a ‘high-risk group’ (HiR) (including ≥ 4 positive axillary lymph nodes (LN), or LN1-3 with ≥ 1 of the following high-risk CPF: Grade 3, tumor size ≥ 5 cm or Ki-67 ≥ 20%) and ‘low-risk group’ (LoR) (do not meet above criteria). Survival analysis was performed on invasive disease-free survival (iDFS), distant relapse-free survival (DRFS), and overall survival (OS) with cutoff date of Sep 30, 2021.

Results

Of the 4088 eligible pts (median age: 50 years), 1310 were identified in HiR (46.6% had LN≥ 4 and 53.4% had LN1-3 with high-risk CPF), and 2778 in LoR (90.8% N0 pts). Pts in HiR were more likely to receive adjuvant chemotherapy (74.9% vs 63.7%) and radiotherapy (72.1% vs 45.6%) than LoR. From 2013 to 2021, the use of aromatase inhibitors and ovarian function suppression in AET gradually increased while the use of selective estrogen receptor modulators (tamoxifen/toremifene) decreased. The 5-year iDFS was 75.3% in HiR and 89.9% in LoR, respectively. Pts in HiR had a higher risk of recurrence or death than pts in LoR (Hazard Ratio: 2.38, 95% CI: 1.82-3.12). Similar results were observed for DRFS and OS (Table). Table: 256P

Risk of recurrence and death in HR+, HER2- early breast cancer¹

*P < 0.05; **P<0.01 CI: Confidence interval; HR: hazards ratio; LN: positive axillary lymph nodes. ¹ HR and 95%CI were estimated from Cox proportional hazards regression models with adjustments for age, menopausal status, neoadjuvant therapy, adjuvant chemotherapy and radiotherapy.

Conclusions

Nearly 25% EBC pts with high-risk CPF experienced recurrence or death within 5 years of initiating AET. Novel treatments are needed to prevent recurrence and death in these pts.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Eli Lilly and Company.

Funding

Eli Lilly and Company.

Disclosure

Y. Yang, T. Li, X. Ma: Financial Interests, Personal, Full or part-time Employment: Eli Lilly and Company; Financial Interests, Personal, Stocks/Shares: Eli Lilly and Company. B. Xu: Financial Interests, Personal, Advisory Board: Novartis, AstraZeneca; Financial Interests, Personal, Invited Speaker: Pfizer, Roche; Financial Interests, Institutional, Research Grant: Henrui. All other authors have declared no conflicts of interest.