-Original-

Neoadjuvant Endocrine Therapy for Operable Breast Cancer: A Retrospective Analysis of Real-World Use

Miki Iwamoto^1,2, Hiroyuki Takei¹, Jun Ninomiya^1,3, Hideki Asakawa^1,4, Tomoko Kurita¹, Keiko Yanagihara^1,5, Shinya Iida^1,6, Takashi Sakatani⁷ and Ryuji Ohashi⁷

¹Department of Breast Surgery and Oncology, Nippon Medical School, Tokyo, Japan
²Department of Breast Surgery, Gyotoku General Hospital, Chiba, Japan
³Ninomiya Hospital, Saitama, Japan
⁴Department of Breast Surgery and Oncology, Tokyo Kyosai Hospital, Tokyo, Japan
⁵Department of Breast Surgery and Oncology, Nippon Medical School Tama Nagayama Hospital, Tokyo, Japan
⁶Department of Breast Surgery and Oncology, Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan
⁷Department of Diagnostic Pathology, Nippon Medical School Hospital, Tokyo, Japan

Background: A retrospective study of the real-world use of neoadjuvant endocrine therapy (NET) is important for standardizing the role of NET in breast cancer care.
Methods: In a consecutive series of women with operable breast cancer who received NET for ≥28 days, associations of NET objectives, NET outcomes, adjuvant chemotherapy use after NET, and survival with clinicopathological factors were examined.
Results: NET objectives were reduction in surgical extent in 49 patients, avoidance of surgery in 31, and treatment until scheduled surgery in 8. The mean duration of NET was 349.5 (range, 34-1,923), 869.8 (range, 36-4,859), and 55.8 (range, 39-113) days, respectively, in these cohorts (success rate: 79.6%, 64.5%, and 100%, respectively), and the differences were significant. Among patients in the former two cohorts, progression-free survival was significantly better in patients with stage 0 or I disease, ductal carcinoma in situ or invasive ductal carcinoma, ≥71% estrogen receptor (ER) positivity, and the surgical extent reduction cohort than the other counterparts. Postoperative chemotherapy use was significantly associated with lymph node metastasis, a high Ki67 labeling index, lymphovascular invasion, and a high preoperative endocrine prognostic index at the time of surgery after NET. Better recurrence-free survival after surgery was significantly associated with high ER expression after NET or high progesterone receptor expression before or after NET.
Conclusions: NET can help reduce surgical extent or avoid surgery in women with early breast cancer, ductal carcinoma, or high ER expression. NET may also aid in decisions related to postoperative systemic therapy to improve survival.

J Nippon Med Sch 2021; 88: 448-460

Keywords
neoadjuvant endocrine therapy, breast cancer, progression, progression-free survival, recurrence-free survival

Correspondence to
Hiroyuki Takei, Department of Breast Surgery and Oncology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan
takei-hiroyuki@nms.ac.jp

Received, December 1, 2020
Accepted, December 11, 2020