- Addition of estrogen deprivation via endocrine therapy (ET) to neoadjuvant chemotherapy (NACT) significantly improved response rates in a trial of patients with stage IIb-IIIc estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer.
- PFS benefit observed in patients with higher baseline Ki-67 index.
Why this matters
- Findings suggest that estrogen deprivation with ET should be routinely added to NACT, particularly if baseline Ki-67 is higher.
- Randomized, controlled CBCSG-036 trial (n=249) of patients given NACT alone or NACT plus letrozole (an aromatase inhibitor) if postmenopausal, or letrozole plus leuprorelin if premenopausal.
- Funding: National Natural Science Foundation of China; others.
- Median follow-up: 26 months.
- Adding ET to NACT yielded a significantly higher objective response rate (ORR, 84.8% vs 72.6%; OR, 2.11; P=.020).
- ORR benefit was even greater in subset with high (>20%) baseline Ki-67 index (91.2% vs 68.7%; P=.001).
- No overall differences between groups in pathologic complete response, pathological response, and 2-year PFS.
- In subanalysis, 2-year PFS benefit observed with ET+NACT vs NACT alone among patients with high Ki-67 index (91.5% vs 76.5%; P=.058).
- No differences between groups in grade 3,4 adverse events.
- Open-label design.
- Short duration of follow-up.