title: High-dose toremifene for fulvestrant-resistant metastatic breast cancer: a report of two cases.
abstract: BACKGROUND
  Hormone receptor (HR)-positive metastatic breast cancer (MBC) is usually treated with hormone therapy. In postmenopausal females, aromatase inhibitors (AIs) are usually used as first-line therapy, and fulvestrant is used subsequently. The optimal treatment beyond fulvestrant has not been established. We experienced two cases in which high-dose toremifene (hdTOR) was effective after the failure of AIs and fulvestrant.
  
  
  METHODS
  A 73-year-old female with HR-positive left breast cancer (T2N1M0) underwent preoperative chemotherapy and mastectomy with axillary dissection. Computed tomography (CT) revealed liver tumors in S7 (23 mm) and S8 (25 mm) during adjuvant letrozole therapy, so fulvestrant was started. The tumors initially decreased in size (23 and 22 mm), but then progressed (36 and 25 mm). Treatment was changed to hdTOR, and the tumors shrunk to 26 mm (S7) and 24 mm (S8), and she was stable for 6 months while receiving hdTOR.
  
  
  METHODS
  An 81-year-old female with HR-positive left breast cancer (T2N1M0) underwent left mastectomy and axillary dissection. CT revealed liver tumors in S7 (20 mm) and S8 (11 mm) during adjuvant letrozole therapy, so fulvestrant treatment was started. The tumor in S7 shrunk (13 mm), but the tumor in S8 slightly progressed (13 mm), and both tumors progressed (14 and 18 mm) after 6 months. Treatment was changed to hdTOR, and the tumors slightly shrunk (12 and 14 mm) after 6 months. hdTOR has been continued for 9 months.
  
  
  CONCLUSIONS
  hdTOR was effective for MBC after multiple hormone therapies, likely because it acts via a different mechanism of action.
authors.affiliation: Department of Breast Surgery, Gifu Prefectural General Medical Center, Gifu, Japan.
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Mori
authors.affiliation: Department of Breast Surgery, Gifu Prefectural General Medical Center, Gifu, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Nagao
keywords: High-dose toremifene; Hormone therapy; Secondary breast neoplasm