Treatment with Aromatase Inhibitors in Postmenopausal Women with Breast Cancer and the Possibility of Influencing Side Effects

Abstract

The third generation aromatase inhibitors (anastrozole, letrozole, exemestane) have become standard endocrine treatment for postmenopausal estrogen receptor - positive breast cancers in all settings (neoadjuvant, adjuvant, metastatic breast cancer), based on superiority to tamoxifen. Aromatase inhibitors interfere with the conversion of androgens into estrogens by blocking the enzyme aromatase resulting in low estradiol levels. Aromatase inhibitors are contraindicated in women with functional ovaries. Many premenopausal women develop amenorrhea after adjuvant chemoterapy. Aromatase inhibitors may promote recovery of ovarian function which could lead to therapeutic failure or even to unexpected pregnancy. Currently available measures to determine the menopausal status are conflicting. This paper focuses primarily on adverse effects of aromatase inhibitors which can lead to non-compliance or to discontinuation of treatment. Many side effects of aromatase inhibitors are related to estrogen deprivation. On the other hand as aromatase inhibitors lack estrogenic activity, they are not associated with serious adverse events typical for tamoxifen, such as endometrial cancer and thromboembolic disease. Aromatase inhibitors therapy is often associated with vasomotor symptoms (hot flashes), vaginal dryness, dyspareunia, bone loss, arthralgias and myalgias (musculoskeletal symptoms). Management of these side effects can lead to improved adherence and persistence with therapy.Key words: breast cancer - menopause - aromatase inhibitors - ovarian function recovery - adverse effectsThis work was supported by Czech Ministry of Health - RVO (MOÚ, 00209805).The author declares she has no potential conflicts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 10. 7. 2016Accepted: 3. 8. 2016.