Abstract 7P
Background
In this study, we investigated the efficacy of short term neoadjuvant endocrine therapy utilizing the waiting period for surgery and the prognostic factor including preoperative endocrine prognostic index (PEPI) score.
Methods
A total of 286 premenopausal women with hormone receptor-positive, HER2-negative breast cancer was treated with endocrine therapy during the waiting period for surgery between October 2012 and May 2024. All premenopausal patients received tamoxifen, and 6 patients received luteinizing hormone-releasing hormone agonists in addition to tamoxifen. The primary endpoint was change in tumor size by ultrasound and Ki67 before and after short-term endocrine therapy. The secondary endpoint was prognosis of patients divided by PEPI score which was calculated using tumor size, lymph node metastasis, Ki67, and ER Allred score. This study was approved by the institutional review board of Teikyo University.
Results
Median age was 47 years old (range, 29-56). ER and PgR was positive in 285 (99%) and 275 (96%) of the entire 286 patients, respectively. Median tumor size was 1.48 cm (range, 0.26-4.32). 4 (1.4%) patients were clinically node-positive. The median duration of endocrine therapy was 44 days (range, 1-116). Average pretreatment Ki67 expression was 14.6% (range, 0-95). Tumor diameter was decreased to 1.45cm (range,0.38-5.95) after short-term endocrine therapy (p=0.3). The Ki67 expression was significantly decreased to 11.5% (range, 0-75) after endocrine therapy (p<0.0001) and 79 patients (27.6%) showed marked increase in Ki67 expression. PEPI score 0, 1-3 and ≥ 4 were found in 27 (9.4%),198 (69.2%) and 61 patients (21.3%), respectively. After a median observation period of 1298 days, there were no significant differences in disease-free survival (DFS) (p=0.11) or overall survival (OS) (p=0.74) between patients with PEPI scores of 0, 1-3, and ≥ 4.
Conclusions
These results suggested that neoadjuvant endocrine therapy during the waiting period for surgery might be effective in reducing the size and Ki67 expression level and PEPI score might be useful in predicting the prognosis of premenopausal hormone receptor positive breast cancer patients.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.