Abstract ES8-1: Adjuvant endocrine therapy in 2020: It's complicated

Abstract

Adjuvant endocrine therapy in 2020: It’s complicated Data regarding the use of adjuvant endocrine therapy in patients with hormone receptor-positive early breast cancer has grown over the past decades, and yet still uncertainty remains in management recommendations. In pre-menopausal women, treatment decisions are often driven by estimation of risk of recurrence, measured in terms of clinical and pathological parameters, algorithm-based prognostic modelling derived from breast cancer registries, molecular profiling and gene signature assays. Despite these significant advances, risk of distant disease recurrence is still over-estimated in a significant proportion of women. The addition of ovarian suppression to tamoxifen in pre-menopausal women has been shown to increase rates of both disease-free survival and overall survival than tamoxifen alone, with the use of the steroidal aromatase inhibitor exemestane producing further higher rates of freedom from recurrence. However, the addition of ovarian suppression in this generally low-risk population comes at the cost of increased adverse events and potential to interpose child-bearing years. Further to this, the SOFT/TEXT studies mandated five years of active treatment; little is known as to whether extended treatment beyond those five years would be comparatively equal, better or worse in terms of outcome endpoints.

In the post-menopausal population, the updated ASCO Clinical Practice Guideline suggests that all women with node-positive disease should be offered extended therapy including an aromatase inhibitor for a total of ten years, as well as women with node-negative disease possessing high-risk prognostic factors. The question of how best to identify those women who may fare equally well with de-escalated, shorter therapy remains open. The issue of adverse events and drug-related side effects, particularly in the setting of extended therapy, is relevant and may impact negatively on overall treatment compliance and quality of life. As such, the choice of endocrine therapy remains an important consideration, as is evidence that intermittent administration of aromatase inhibitors may be feasible in selected patients.

CDK4/6 inhibitors, administered in tandem with endocrine therapy, have radically changed the approach to managing metastatic endocrine receptor-positive disease. There is now much interest in moving these agents forward into the neoadjuvant and adjuvant setting, with a number of phase II and III trials ongoing. If positive data is consistently reported in adjuvant studies, this will undoubtedly create another layer of complexity to the clinical management of endocrine-sensitive disease.

Citation Format: A McCartney, A Di Leo. Adjuvant endocrine therapy in 2020: It's complicated [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr ES8-1.