The impact of endoxifen-guided tamoxifen dose reductions on endocrine side-effects in patients with primary breast cancer

ESMO Open

article

S.M. Buijs¹  E. Oomen-de Hoop¹  C.L. Braal¹  M.M. van Rosmalen¹  J.C. Drooger²  Q.C. van Rossum-Schornagel³  M.B. Vastbinder⁴  S.L.W. Koolen¹  A. Jager¹  R.H.J. Mathijssen¹ 

[1] Department of Medical Oncology, Erasmus MC Cancer Institute;Department of Medical Oncology, Breast Cancer Center South Holland South, Ikazia Hospital;Department of Internal Medicine;Department of Internal Medicine, IJsselland Hospital;Department of Hospital Pharmacy, Erasmus University Medical Center

关键词: early breast cancer;    endoxifen;    side-effects;    therapeutic drug monitoring;    dose reduction;   

DOI  :  10.1016/j.esmoop.2023.100786

学科分类：社会科学、人文和艺术（综合）

来源: BMJ Publishing Group

【 摘 要 】

Background Tamoxifen is important in the adjuvant treatment of hormone-sensitive breast cancer and substantially reduces recurrence; however, almost 50% of patients are non-compliant mainly due to side-effects. The aim of this study was to investigate whether endoxifen-guided tamoxifen dose reduction could lead to fewer side-effects.Materials and methods Effects of tamoxifen dose reduction were investigated in patients with bothersome side-effects and endoxifen levels ≥32 nM and compared to patients with side-effects who remained on tamoxifen 20 mg. Endocrine symptoms and health-related quality of life (HR-QOL) were assessed after 3 months with the Functional Assessment of Cancer Therapy—Endocrine Symptoms (FACT-ES) questionnaire.Results Tamoxifen dose was reduced in 20 patients, 17 of whom were assessable for side-effect analyses. A clinically relevant improvement of 6 points was observed in endocrine symptoms and HR-QOL in 41% and 65% of the patients, respectively. In total, there was a significant and clinically relevant improvement in endocrine symptoms [5.7, 95% confidence interval (CI) −0.5-11.5] and HR-QOL (8.2, 95% CI 0.9-15.4) after dose reduction. This was not seen in patients whose doses were not reduced (n = 60). In 21% of patients, endoxifen dropped slightly below the 16-nM threshold (12.8, 15.5, 15.8, 15.9 nM).Conclusions Endoxifen-guided dose reduction of tamoxifen significantly improved tamoxifen-related side-effects and HR-QOL. Nearly 80% of patients remained above the most conservative endoxifen threshold.

【 授权许可】

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