Switching to aromatase inhibitor (AI) after tamoxifen in premenopausal patients with chemotherapy-induced amenorrhea (CIA) after early breast cancer treatment.

Abstract

e11099 Background: AI are contraindicated in women with functioning ovaries as the reduced feedback of estrogen leads to an increased secretion of gonadotropins. Previous data obtained in our center confirms that the incidence of CIA among premenopausal patients is 75.5% - 82.7% depending on the chemotherapy administered. The aim of our study was to analyze outcome in terms of ovarian function recovery in premenopausal patients treated with tamoxifen that switched to AI after long-term CIA (>1 year) and/or estradiol levels < 20 pmol. Methods: 102 patients diagnosed with hormone-sensitive early breast cancer at the Hospital Clinico of Valencia, and clinically premenopausal at diagnosis were included from May 2004 to December 2009. All patients were treated with chemotherapy in the adjuvant or neoadjuvant setting, and adjuvant tamoxifen. Patients had to accomplish criteria of postmenopausal status at the time of switching defined as a period of CIA of more than 1 year and/or levels of estradiol < 20 pmol/L. Results: Median age at switching was 49.8 years, 81 patients were 45 years or older, 19 patients were 40-44 years and 2 treated with high-dose chemotherapy were younger than 40 years. 40% received both anthracyclines and taxanes and 14% high-dose adjuvant chemotherapy. 87 patients were switched after at least 2 years of tamoxifen, and to 15 patients switching was offered earlier due to tamoxifen intolerance. Monitoring of estradiol levels was obtained in 55 patients (53.9%) at the time of switch, of whom 46 presented levels of estradiol < 20 pmol/L. In 9 patients (7.8%) ovarian function returned with renewal of menses and serum estradiol levels > 20 pmol/L. None of the patients younger than 40 returned to normal ovarian function. Conclusions: AI should be used with caution in premenopausal patients after CIA. However, with an appropriate monitoring and follow-up, incidence of recovery of ovarian function occured in only 7.8% of the patients. Switch to an AI in patients younger than 40 with CIA after high dose CT may be a safe procedure.