270P - Influence of neoadjuvant chemotherapy-induced short-term amenorrhea on pathologic response and treatment outcome in ER+HER2- breast cancer

Background

Premenopausal women experience temporary ovarian function suppression (OFS) during the period of chemotherapy. In ER+ breast cancer, chemotherapy-induced temporary OFS may offer anti-estrogenic effect in addition to direct cytotoxic anti-tumor effect. It is unclear whether anti-estrogenic effect by temporary OFS during neo-adjuvant chemotherapy (NAC) enhance anti-tumor effect. Based on pathologic complete response (pCR) and complete cell-cycle arrest (CCCA), we compared pathologic response and outcomes between younger and older patients with ER+HER2- breast cancer treated with NAC.

Methods

Between 2007 January and 2021 June, we retrospectively identified 1,178 patients with ER+HER2- breast cancer who underwent NAC in the Gangnam Severance Hospital and the Asan Medical Center. We compared the pCR rate according to age under 45 and over 55 and investigated durations of NAC, clinical stage, and Ki-67. Pathologic complete response was defined as no invasive residual disease in both breast and axillae. In addition, we collected available Ki67 expression in surgical specimen after NAC. We defined low Ki67 with a cutoff of 2.7%. The recurrence-free survival was evaluated in patients with post-NAC Ki67.

Results

In all 1,178 patients, the pCR rate was 1.9% (22/1,178). The rate was 1.4% (8/552) in younger patients (age ≤45), whereas it was 3.6% (9/250) in older patients (age ≥55) (p= 0.063, Chi-square test). In 524 patients who received NAC consisting of anthracyclines and taxanes with a duration of NAC longer than 6 months, the pCR rate did not differ between the younger patients and the older (2.1%, 5/243 vs. 2.8%, 3/106; p= 0.703). In patients with post-NAC Ki67, the CCCA rates were 66.2% (307/464) in the younger and 39.8% (86/216) in the older, respectively (p<0.001). Survival analyses showed that, compared to patients with CCCA, those without CCCA experienced a significant decrease in RFS in both younger and older women.

Conclusions

While short-term OFS resulting from NAC led to a higher rate of CCCA in premenopausal women, younger women had notably poorer survival outcomes compared to older women. Among premenopausal women, achieving CCCA was associated with a slight improvement in treatment outcomes.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Gangnam Severance Hospital.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.