Postmenopausal hormone therapy and breast cancer: What is the problem?

Progestagen component in combined hormone replacement therapy in postmenopausal women and breast cancer risk: a debated clinical issue

The relevance of the progestagen component in combined hormone replacement therapy (HRT) for breast cancer risk has been long debated. In vitro studies have shown that progestins exert both genomic transcriptional and non-genomic effects that can enhance the proliferation, invasiveness and spread of breast cancer cells. According to a novel hypothesis, progestins can still activate cancer stem cells in patients with pre-existing, clinically undetected breast cancer. However, some experimental and clinical data suggest that different progestins may have a different impact on the pathophysiology of malignant breast cells. In vitro studies on estrogen receptor (ER)+ breast cancer cells have shown that the addition of medroxyprogesterone acetate (MPA) to estradiol (E(2)) produces a significantly higher increase of the mRNA levels and activities of estrogen-activating enzymes aromatase, 17beta hydroxysteroid dehydrogenase type-1 and sulfatase when compared with progesterone plus E(2). In randomised trial performed on ovariectomised adult female monkeys, oral E(2) plus MPA have resulted in a significantly greater proliferation of breast lobular and ductal epithelium when compared with placebo, whereas E(2) plus micronised progesterone have not. In the same experimental model, oral E(2) plus MPA have been found to induce the expression of genes encoding epidermal growth factor receptor (EGFR) ligands and downstream targets, whereas E(2) alone or E(2) plus micronised progesterone had no or modest effects on EGFR-related genes. In last years, some clinical studies on HRT users have shown that androgenic progestin- or MPA-based formulations are associated with an increased breast cancer incidence, whereas micronised progesterone- or dydrogesterone-based formulations are not. Further basic and clinical investigations on this topic are strongly warranted to elucidate whether the choice of the progestagen component in combined HRT could be of clinical relevance as for breast cancer risk.

Effects of estradiol and progestogens on tumor-necrosis factor-alpha-induced changes of biochemical markers for breast cancer growth and metastasis

BACKGROUND

Epidemiological data suggest an enhanced breast cancer risk during estrogen/progestogen therapy as compared to estrogen monotherapy in postmenopausal women. The underlying mechanism, however, still remains unknown. Estrogens are known to be mitogenic agents for benign and cancerous breast epithelial cells whereas the role of progestogens is unclear. Tumor-associated macrophages play a crucial role in tumor growth and metastasis due to the synthesis of various cytokines such as tumor necrosis factor-alpha (TNF-alpha), which can stimulate the synthesis of proliferative and angiogenic factors in tumor cells. In an in vitro model we investigated the influence of estradiol and estradiol/progestogens combinations on the changes of TNF-alpha- induced markers.

METHODS

MCF-7 cells, a human estrogen- and progesterone-receptor-positive human breast cancer cell line, were used for the experiments. Estradiol (E(2)), at a concentration of 0.1 nM, and the progestogens progesterone (P), norethisterone (NET) and medroxyprogesterone acetate (MPA), each at concentrations of 0.01 to 1 microM, were tested alone and in combination. The cells were incubated for 4 days and the markers monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) were measured in the supernatant by enzyme-linked immunosorbent assay.

RESULTS

E(2) in combination with TNF-alpha elicited significant increases in MCP-1 and VEGF concentrations compared with TNF-alpha alone. For the progestogens alone an increase of MCP-1 was observed for NET, whereas MPA induced a decrease. An increase of VEGF was observed for all progestogens, the effect being greatest for MPA. No changes were found for MMP-9. In combinations with E(2), the E(2)-induced increase of MCP-1 was reduced by NET and MPA and the increase of VEGF was diminished by P and NET, but not by MPA. The E(2)-induced decrease of MMP-9 was not antagonized by P and NET, but completely abolished by MPA.

CONCLUSION

Our results indicate that E(2) may have a stimulating effect on pre-existing tumor growth and metastasis. This effect seems to be influenced by progestogens in a different manner. Thus the choice of progestogen addition to estrogen therapy may be important, especially since different effects can occur in the case of pre-existing tumor cells.

Could transdermal estradiol + progesterone be a safer postmenopausal HRT? A review

Hormone replacement therapy (HRT) in young postmenopausal women is a safe and effective tool to counteract climacteric symptoms and to prevent long-term degenerative diseases, such as osteoporotic fractures, cardiovascular disease, diabetes mellitus and possibly cognitive impairment. The different types of HRT offer to many extent comparable efficacies on symptoms control; however, the expert selection of specific compounds, doses or routes of administration can provide significant clinical advantages. This paper reviews the role of the non-oral route of administration of sex steroids in the clinical management of postmenopausal women. Non-orally administered estrogens, minimizing the hepatic induction of clotting factors and others proteins associated with the first-pass effect, are associated with potential advantages on the cardiovascular system. In particular, the risk of developing deep vein thrombosis or pulmonary thromboembolism is negligible in comparison to that associated with oral estrogens. In addition, recent indications suggest potential advantages for blood pressure control with non-oral estrogens. To the same extent, a growing literature suggests that the progestins used in association with estrogens may not be equivalent. Recent evidence indeed shows that natural progesterone displays a favorable action on the vessels and on the brain, while this might not be true for some synthetic progestins. Compelling indications also exist that differences might also be present for the risk of developing breast cancer, with recent trials indicating that the association of natural progesterone with estrogens confers less or even no risk of breast cancer as opposed to the use of other synthetic progestins. In conclusion, while all types of hormone replacement therapies are safe and effective and confer significant benefits in the long-term when initiated in young postmenopausal women, in specific clinical settings the choice of the transdermal route of administration of estrogens and the use of natural progesterone might offer significant benefits and added safety.

Safety of tibolone in the treatment of vasomotor symptoms in breast cancer patients--design and baseline data 'LIBERATE' trial

Many patients with a history of breast cancer (BC) will suffer from vasomotor symptoms, which can be induced or exacerbated by treatment with tamoxifen or aromatase inhibitors. The LIBERATE trial was designed as a randomized, double-blind, multicenter trial to demonstrate that tibolone 2.5mg/day (Livial) is non-inferior to placebo regarding BC recurrence in women with vasomotor symptoms surgically treated for primary BC within the last 5 years. Secondary objectives are effects on vasomotor symptoms as well as overall survival, bone mineral density and health-related quality of life. Mean age at randomization was 52.6 years, and the mean time since surgery was 2.1 years. The mean daily number of hot flushes and sweating episodes was 7.3 and 6.1, respectively. For the primary tumor, Stage IIA or higher was reported for >70% of the patients. In subjects whose receptor status was known, 78.2% of the tumors were estrogen receptors positive. At randomization, tamoxifen was given to 66.2% of all patients and aromatase inhibitors to 7%. Chemotherapy was reported by 5% at randomization. The adjuvant tamoxifen use in LIBERATE allows a comparison with the Stockholm trial (showing no risk of BC recurrence associated with hormone therapy), which was stopped prematurely subsequent to HABITS. The LIBERATE trial is the largest, ongoing, well-controlled study for treatment of vasomotor symptoms in BC patients.

Breast cancer and climacteric complaints: Weighing up risks of hormone therapy against quality of life

Women with severe menopausal symptoms can, at their request, be treated effectively with hormone therapy. Good information about the advantages and disadvantages of hormone therapy should precede this decision. For women with breast cancer or an inherited increased risk of breast cancer and severe, often therapy-related climacteric symptoms, a high degree of reticence is appropriate in relation to hormone therapy. If the quality of life is seriously affected in these often-young women with these iatrogenic climacteric complaints, then careful consideration must be given to the various treatment modalities.

Current breast cancer risks of hormone replacement therapy in postmenopausal women

The controversies surrounding hormone replacement therapy have left many women confused and afraid. Providers have been faced with long-standing assumptions challenged by an abundance of new data in the past few years, with little guidance on how to interpret these findings. The objective of this paper is to provide a framework for understanding breast cancer risk associated with postmenopausal hormone replacement therapy, with a particular focus on how observational studies and randomised trials provide complementary information. This framework considers the data on risks of various hormonal preparations, the profiles of women at risk, and ends with an expert opinion in this context.