Estrogen deprivation for breast cancer prevention

GRACE-trial: a randomised active-controlled trial for vulvovaginal atrophy in patients with breast cancer on endocrine therapy - study protocol

INTRODUCTION

Breast cancer is the most common cancer type in women worldwide. Due to hormone receptor positivity in the majority of the breast cancer tumours is endocrine therapy a crucial part in the treatment landscape of breast cancer. Endocrine therapy consists of the use of selective oestrogen-receptor modulators or aromatase inhibitors. These medicines generate a hypoestrogenic environment by reducing circulating oestrogen or by altering the effect of oestrogen on tissue cells by receptor blockade. As a common side effect, vulvovaginal atrophy occurs in the majority of patients with breast cancer using endocrine therapy. Vulvovaginal atrophy has a significant impact on physical and psychological well-being due to negative influence on quality-of-life, self-esteem and sexuality. As a consequence, adherence to endocrine therapy for the standard duration of 5-10 years is challenging, resulting in higher rates of therapy interruption, leading to poorer prognosis with shorter distant disease-free survival. The standard treatment for vulvovaginal atrophy in postmenopausal women is based on the use of local hormonal treatment. However, when a patient has a history of breast cancer, delay of treatment and undertreatment are ubiquitous.

METHODS AND ANALYSIS

In this first ever prospective randomised trial patients with breast cancer on endocrine therapy with vulvovaginal atrophy will be treated with the available local treatment modalities with a 1:1:1:1 randomisation: oestrogen, dehydroepiandrosterone, moisturisers and a co-treatment of oestrogen and probiotics. Patient-reported outcomes measurements will be implemented to investigate the efficacy of the implemented treatments. Safety of the treatments will be evaluated by assessing systemic sex hormones concentrations.

ETHICS AND DISSEMINATION

This study was approved by the Ethical Committee of Ghent University Hospital and by the Federal Agency for Medicines and Health Products. Results will be published in peer-reviewed journals and released in international conferences.

TRIAL REGISTRATION NUMBER

2021-001921-31.

Microenvironmental Determinants of Breast Cancer Metastasis: Focus on the Crucial Interplay Between Estrogen and Insulin/Insulin-Like Growth Factor Signaling

The development and progression of the great majority of breast cancers (BCs) are mainly dependent on the biological action elicited by estrogens through the classical estrogen receptor (ER), as well as the alternate receptor named G-protein–coupled estrogen receptor (GPER). In addition to estrogens, other hormones and growth factors, including the insulin and insulin-like growth factor system (IIGFs), play a role in BC. IIGFs cooperates with estrogen signaling to generate a multilevel cross-communication that ultimately facilitates the transition toward aggressive and life-threatening BC phenotypes. In this regard, the majority of BC deaths are correlated with the formation of metastatic lesions at distant sites. A thorough scrutiny of the biological and biochemical events orchestrating metastasis formation and dissemination has shown that virtually all cell types within the tumor microenvironment work closely with BC cells to seed cancerous units at distant sites. By establishing an intricate scheme of paracrine interactions that lead to the expression of genes involved in metastasis initiation, progression, and virulence, the cross-talk between BC cells and the surrounding microenvironmental components does dictate tumor fate and patients’ prognosis. Following (i) a description of the main microenvironmental events prompting BC metastases and (ii) a concise overview of estrogen and the IIGFs signaling and their major regulatory functions in BC, here we provide a comprehensive analysis of the most recent findings on the role of these transduction pathways toward metastatic dissemination. In particular, we focused our attention on the main microenvironmental targets of the estrogen-IIGFs interplay, and we recapitulated relevant molecular nodes that orientate shared biological responses fostering the metastatic program. On the basis of available studies, we propose that a functional cross-talk between estrogens and IIGFs, by affecting the BC microenvironment, may contribute to the metastatic process and may be regarded as a novel target for combination therapies aimed at preventing the metastatic evolution.

Energy restriction for breast cancer prevention

Weight gain in adult life is an important risk factor for breast cancer. Observational studies indicate that pre- or postmeno-pausal weight loss is associated with a reduction in risk of postmenopausal breast cancer. Here we summarise lifestyle changes including continuous or intermittent energy restriction and/or exercise which may be beneficial for preventing breast cancer and also potential pharmacological approaches to prevention using energy restriction mimetic agents (ERMAs).

The endocrine prevention of breast cancer

Breast cancer incidence is increasing in all parts of the world. Although in Western countries death rates are declining, there is a need to make attempts to prevent the disease in order to reduce the trauma of diagnosis and treatment. Endocrine approaches to breast cancer prevention have been the most successful approach to cancer prevention to date. Studies with tamoxifen were initiated when it was noted that, during adjuvant treatment after surgery to prevent relapse, the incidence of new contralateral cancers was reduced by half. Four trials of >or=5 years of tamoxifen compared with placebo in women at increased risk of breast cancer were initiated in the 1980s and showed a similar reduction in breast cancer, but only in oestrogen-receptor-positive disease. Recent follow-up indicated that there is a carry-over effect of tamoxifen after the completion of treatment at 5 years so that the preventive effect at 10 years is significantly great than at 5. The selective oestrogen receptor modulator (SERM) raloxifene has also been assessed as a preventive agent in two major international randomized trials compared with placebo and shows a protective effect similar to that of tamoxifen. An American study subsequently compared tamoxifen and raloxifene in a trial of nearly 20,000 women at increased risk (the STAR trial) and demonstrated that the two agents were equally effective but that the toxicity of raloxifene was less. Adjuvant trials comparing tamoxifen and the modern potent aromatase inhibitors (anastrozole, letrozole and exemestane) indicate that they are superior to tamoxifen and reduce contralateral breast cancer by approximately 70%. This observation has led to the initiation of two trials in postmenopausal women comparing anastrozole (the IBISII trial) or exemestane (the MAP-3 trial) with placebo. Currently it is recommended that tamoxifen is used to prevent breast cancer in premenopausal women and raloxifene for postmenopausal women (it is not effective in the premenopausal group),and we await the results of the aromatase inhibitor trials.

Exemestane's 17-hydroxylated metabolite exerts biological effects as an androgen

Aromatase inhibitors (AI) are being evaluated as long-term adjuvant therapies and chemopreventives in breast cancer. However, there are concerns about bone mineral density loss in an estrogen-free environment. Unlike nonsteroidal AIs, the steroidal AI exemestane may exert beneficial effects on bone through its primary metabolite 17-hydroexemestane. We investigated 17-hydroexemestane and observed it bound estrogen receptor alpha (ERalpha) very weakly and androgen receptor (AR) strongly. Next, we evaluated 17-hydroexemestane in MCF-7 and T47D breast cancer cells and attributed dependency of its effects on ER or AR using the antiestrogen fulvestrant or the antiandrogen bicalutamide. 17-Hydroexemestane induced proliferation, stimulated cell cycle progression and regulated transcription at high sub-micromolar and micromolar concentrations through ER in both cell lines, but through AR at low nanomolar concentrations selectively in T47D cells. Responses of each cell type to high and low concentrations of the non-aromatizable synthetic androgen R1881 paralleled those of 17-hydroexemestane. 17-Hydroexemestane down-regulated ERalpha protein levels at high concentrations in a cell type-specific manner similarly as 17beta-estradiol, and increased AR protein accumulation at low concentrations in both cell types similarly as R1881. Computer docking indicated that the 17beta-OH group of 17-hydroexemestane relative to the 17-keto group of exemestane contributed significantly more intermolecular interaction energy toward binding AR than ERalpha. Molecular modeling also indicated that 17-hydroexemestane interacted with ERalpha and AR through selective recognition motifs employed by 17beta-estradiol and R1881, respectively. We conclude that 17-hydroexemestane exerts biological effects as an androgen. These results may have important implications for long-term maintenance of patients with AIs.