Long-term effects of tibolone on mammographic density

Tibolone and Breast Tissue: a Review

The safety profile of hormone replacement therapy (HRT) on breast is still controversial. Tibolone is an option of treatment for climacteric syndrome of postmenopausal women. Its risk profile on breast is debated. This is an updated narrative review focusing on the impact of tibolone on breast. Particularly, we will report data from major preclinical and clinical studies regarding the effects of the use of this compound on breast tissue and breast density. Moreover, we will analyze and discuss the most relevant findings of the principal studies evaluating the relationship between tibolone and breast cancer risk. Our purpose is making all clinicians who are particularly involved in women's health more aware of the effects of this compound on breast and, thus, more experienced in the management of menopausal symptoms with this drug. According to the available literature, tibolone seems to be characterized by an interesting safety profile on breast tissue.

The management of menopausal symptoms in women following treatment for cancer at a specialist menopause service

OBJECTIVE

The aim of this study was to identify prescribing patterns at a specialist menopause service in a central London teaching hospital for women following treatment for a malignancy.

STUDY DESIGN

This was a prospective cohort study with data collected over a seven-month period from December 2019 to June 2020. All women reviewed at the specialist menopause services following treatment of a malignancy, BRCA carriers and Lynch syndrome were included in the study, with management options divided into three categories: hormonal, non-hormonal and no treatment.

MAIN OUTCOME MEASURES

The primary outcome of this study was to identify prescribing patterns for all women reviewed following a diagnosis of a malignancy, as well as those with genetic mutations necessitating risk-reducing prophylactic bilateral salpingo-oopherectomy (BSO).

RESULTS

Altogether 71 women were included in this study, with the majority of women post management of a non-gynaecological malignancy (51/71, 72%), of which breast cancer was the most common (37/71, 52%). While non-hormonal treatment was the most popular among those treated for breast cancer, for all other malignancies, hormonal treatment was more widespread. Fourteen women also had genetic mutations, with all of these women commencing hormonal treatment post risk reducing surgery.

CONCLUSION

With the exception of those with a history of hormone-sensitive breast cancer, the use of hormonal treatment for menopausal symptoms remained widespread. While this was a relatively small study, the need for long-term follow-up across specialist menopause services, to assess the risk of recurrence is vital.

Menopause hormone therapy: latest developments and clinical practice

Menopause hormone therapy (MHT) is the most efficient treatment for symptoms of acute climacteric syndrome and for efficient prevention of long-term estrogen deficiency. Vaginal administration of low doses of estrogen is a therapy of choice for treatment and prevention of urogenital atrophy and its consequences. Systemic treatment may include estrogen, but an equally efficient alternative is tibolone. Nonhormonal therapy relies on phytoestrogens, black cohosh extract, and serotonin reuptake inhibitors.

Updated clinical recommendations for the use of tibolone in Asian women

Tibolone, which is indicated for the relief of climacteric symptoms and the prevention of osteoporosis in postmenopausal women, has a tissue-specific mode of action different to that of conventional hormone replacement therapy (HRT). A large proportion of Asian postmenopausal women experience symptoms that most frequently include musculoskeletal pain, insomnia, forgetfulness, hot flushes and sexual dysfunction, and there is a need to address their specific requirements. Recent studies show that, in comparison to HRT, tibolone is as effective in alleviating menopausal symptoms and preventing bone loss, has a greater positive effect on sexual dysfunction and is associated with less vaginal bleeding, but it is rarely mentioned in guidelines for menopausal treatment. Levels of awareness amongst women about treatments for menopausal symptoms vary between Asian countries but, even in countries where awareness is high, HRT usage is much lower than in the West. To provide a practical approach to the use of tibolone in Asian postmenopausal women, a panel of experts in the management of menopause from 11 Asia Pacific countries has developed recommendations for its use, based on the evidence from clinical studies published since 2005. However, as much of the clinical data reviewed are from international studies, the recommendations and the treatment algorithm presented here are widely applicable.

Tibolone and breast cancer

Tibolone is a relatively new drug for postmenopausal women, which is structurally related to 19-nortestosterone derivatives and exhibits weak oestrogenic, progestogenic and androgenic activities. The effect of tibolone on breast tissue is still obscure. In vitro studies have shown conflicting results regarding the effects of tibolone on breast cells. On the other hand, although epidemiological studies show an increase in the risk of breast cancer among women treated with tibolone, accumulation of data obtained from radiological studies presents promising results. However, the safety of tibolone with regard to breast tissue needs to be investigated further, especially through well-designed, large-scale, randomised-controlled trials.

Hormone replacement therapy and false positive recall in the Million Women Study: patterns of use, hormonal constituents and consistency of effect

INTRODUCTION

Current and recent users of hormone replacement therapy (HRT) have an increased risk of being recalled to assessment at mammography without breast cancer being diagnosed ('false positive recall'), but there is limited information on the effects of different patterns of HRT use on this. The aim of this study is to investigate in detail the relationship between patterns of use of HRT and false positive recall.

METHODS

A total of 87,967 postmenopausal women aged 50 to 64 years attending routine breast cancer screening at 10 UK National Health Service Breast Screening Units from 1996 to 1998 joined the Million Women Study by completing a questionnaire before screening and were followed for their screening outcome.

RESULTS

Overall, 399 (0.5%) participants were diagnosed with breast cancer and 2,629 (3.0%) had false positive recall. Compared to never users of HRT, the adjusted relative risk (95% CI) of false positive recall was: 1.62 (1.43-1.83), 1.80 (1.62-2.01) and 0.76 (0.52-1.10) in current users of oestrogen-only HRT, oestrogen-progestagen HRT and tibolone, respectively (p (heterogeneity) < 0.0001); 1.65 (1.43-1.91), 1.49 (1.22-1.81) and 2.11 (1.45-3.07) for current HRT used orally, transdermally or via an implant, respectively (p (heterogeneity) = 0.2); and 1.84 (1.67-2.04) and 1.75 (1.49-2.06) for sequential and continuous oestrogen-progestagen HRT, respectively (p (heterogeneity) = 0.6). The relative risk of false positive recall among current users appeared to increase with increasing time since menopause, but did not vary significantly according to any other factors examined, including duration of use, hormonal constituents, dose, whether single- or two-view screening was used, or the woman's personal characteristics.

CONCLUSION

Current use of oestrogen-only and oestrogen-progestagen HRT, but not tibolone, increases the risk of false positive recall at screening.