Affiliations: [a] Department of Surgery, Sakai City Medical Center, Osaka, Japan | [b] Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osaka, Japan
Correspondence:
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Corresponding author: Jun Yamamura, Department of Surgery, Sakai City Medical Center, 1-1-1, Ebaraji-cho, Nishi-ku, Sakai City, Osaka 593-8304, Japan. Tel.: +81 722721199; Fax: +81 722729911; E-mail: june10th68@gmail.com
Abstract: BACKGROUND:Current guidelines define primary and secondary endocrine resistance according to the periods of adjuvant endocrine therapy (adj-ET); however, the relationship between adj-ET period and endocrine resistance remains unclear. OBJECTIVE:We examined progression-free survival (PFS) after primary ET for recurrent hormone receptor-positive/HER2-negative breast cancer, and evaluated the relationship between endocrine resistance and the periods of adj-ET. METHODS:We assessed PFS among 183 patients who received ET as primary treatment for the first recurrence, according to the period of adj-ET (adj-ET < 1 year, 1–2 years, ≥2 years, and completion). RESULTS:Patients who relapsed during the first year of adj-ET had the significantly shortest PFS. PFS did not significantly differ between patients who relapsed at 1–2 years of adj-ET and patients who relapsed while on adj-ET but after the first 2 years. CONCLUSIONS:Relapse at 1–2 years after adj-ET initiation might be better classified as secondary endocrine resistance rather than primary endocrine resistance.
