[Tolerance of Tamoxifen as an adjuvant therapy and long-term follow up of 55 premenopausal breast cancer women, cared for at the Institut de cancérologie de Lorraine, treated with Tamoxifen].

Introduction: Objectives: the purpose of this study is to assess TAM safety in terms of side effects and hormonal status, the persistence of the treatment over a five years time-frame and to report the remote follow-up data.

Methods: Fifty five patients were included patients between January 2001 and November 2002 at the Institut de cancérologie de Lorraine. The subjects were aged 50 years or less, premenopausal at diagnosis and treated with adjuvant TAM therapy at a daily dose of 20 mg, for an expected duration of 5 years, at a daily. After 2 years, prospective evaluation was completed and monitoring of ovarian function was performed as usual in the institution (1x/year). All data were retrospectively evaluated in 2019.

Results: In these 55 patients, the cumulative incidences of cysts and hot flushes 5 years after treatment were 68.5 % and 77.6 %, respectively. Of the 33 patients with chemoreactive amenorrhea, half had cycles which resumed within a median of 9 months. In the 10 patients without chemotherapy-induced amenorrhea, 4 had a cycle stop. Of these, 3 patients had cycles that, resumed within 1, 4 and 8 months. 34 patients (61.3 %) had taken Tamoxifen for at least 5 years. After 15 years of treatment, overall and progression-free survival was 90.7 % and 67.4 %, respectively.

Conclusion: The observation of the tolerance to the treatment for 5 years and beyond, contributes to the quality of information delivered to future patients starting the treatment, allowing a better understanding and in the long term a better observance.