Adjuvant and extended adjuvant use of aromatase inhibitors: Reducing the risk of recurrence and distant metastasis

Oncologic risks of autologous fat grafting to the breast

As the frequency of fat grafting to the breast has increased, some investigators have raised the possibility that this procedure may potentially increase the risks associated with breast cancer. Their concerns included not only interference with cancer detection, but also promotion of tumor formation or recurrence mediated by mechanisms such as aromatase expression, angiogenesis, and tumor stromal cells. However, published clinical studies describing outcomes of fat grafting to the breast in more than 2000 patients have not reported any increase in new or recurrent cancers. The reason for this apparent disconnect may lie in the small sample sizes and relatively short follow-up, but it may also reside in the considerable gap between laboratory studies or theoretical considerations suggesting potential risks and the actual clinical practice. This review discusses potential risks of current and novel approaches to autologous fat grafting to the breast within the context of both the underlying science and clinical practice.

Understanding and optimizing bone health in breast cancer

Bone is the preferred site of metastasis for breast cancer, and presence of skeletal lesions is associated with significant morbidity and poor prognosis. Skeletal-related effects such as pain, pathologic fractures, spinal compression, and hypercalcemia are frequent consequences of skeletal lesions of breast cancer that have debilitating effects on the patients' quality of life. In addition to direct cancer effects on the skeleton, therapies commonly used to treat patients with breast cancer such as chemotherapy and aromatase inhibitors (AI) result in cancer therapy-induced bone loss (CTIBL) which is associated with increased risk of skeletal complications such as fractures. Bisphosphonates are a class of antiresorptive drugs that are now firmly established as the cornerstone of the management of skeletal-related events due to breast cancer. Other novel bone-targeting agents such as the anti-receptor activator of NF-κB ligand (RANKL) monoclonal antibody denosumab are also showing promising activity in the treatment of bone metastasis secondary to breast cancer. Moreover, recent provocative evidence suggests that bisphosphonates might also exhibit antitumor activity via direct and indirect mechanisms. The goal of this review is to summarize the pathophysiology of osteolytic bone lesions secondary to breast cancer, provide clinical evidence of currently available bone-targeted drugs in the treatment of bone metastasis and CTIBL, and explore the antitumor activity of current bone-targeted agents in patients with breast cancer.

Growth factor receptors and apoptosis regulators: signaling pathways, prognosis, chemosensitivity and treatment outcomes of breast cancer

Biomarkers of breast cancer are necessary for prognosis and prediction to chemotherapy. Prognostic biomarkers provide information regarding outcome irrespective of therapy, while predictive biomarkers provide information regarding response to therapy. Candidate prognostic biomarkers for breast cancers are growth factor receptors, steroid receptors, Ki-67, cyclins, urokinase plasminogen activator, p53, p21, pro- and anti-apoptotic factors, BRCA1 and BRCA2. But currently, the predictive markers are Estrogen and Progesterone receptors responding to endocrine therapy, and HER-2 responding to herceptin. But there are numerous breast cancer cases, where tamoxifen is ineffective even after estrogen receptor positivity. This lead to search of new prognostic and predictive markers and the number of potential markers is constantly increasing due to proteomics and genomics studies. However, most biomarkers individually have poor sensitivity or specificity, or other clinical value. It can be resolved by studying various biomarkers simultaneously, which will help in better prognosis and increasing sensitivity for chemotherapeutic agents. This review is focusing on growth factor receptors, apoptosis markers, signaling cascades, and their correlation with other associated biomarkers in breast cancers. As our knowledge regarding molecular biomarkers for breast cancer increases, prognostic indices will be developed that combine the predictive power of individual molecular biomarkers with specific clinical and pathologic factors. Rigorous comparison of these existing as well as emerging markers with current treatment selection is likely to see an escalation in an era of personalized medicines to ensure the breast cancer patients receive optimal treatment. This will also solve the treatment modalities and complications related to chemotherapeutic regimens.

Aromatase inhibitors in breast cancer

Estrogens play important roles in breast cancer development and progression. In postmenopausal women, traditional endocrine therapies such as tamoxifen have sought to inhibit estrogen action by targeting the estrogen receptor itself. However, newer treatments are evolving that target estrogen production in postmenopausal tissues through inhibition of the aromatase enzyme. Clinical data demonstrate that these aromatase inhibitors are superior to tamoxifen as adjuvant therapy for breast cancer and have now replaced tamoxifen as first line therapy in a number of treatment regimens for postmenopausal breast cancer patients.

Stimulating the GPR30 estrogen receptor with a novel tamoxifen analogue activates SF-1 and promotes endometrial cell proliferation

Estrogens and selective estrogen receptor (ER) modulators such as tamoxifen are known to increase uterine cell proliferation. Mounting evidence suggests that estrogen signaling is mediated not only by ERalpha and ERbeta nuclear receptors, but also by GPR30 (GPER), a seven transmembrane (7TM) receptor. Here, we report that primary human endometriotic H-38 cells express high levels of GPR30 with no detectable ERalpha or ERbeta. Using a novel tamoxifen analogue, STX, which activates GPR30 but not ERs, significant stimulation of the phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways was observed in H-38 cells and in Ishikawa endometrial cancer cells expressing GPR30; a similar effect was observed in JEG3 choriocarcinoma cells. STX treatment also increased cellular pools of phosphatidylinositol (3,4,5) triphosphate, a proposed ligand for the nuclear hormone receptor SF-1 (NR5A1). Consistent with these findings, STX, tamoxifen, and the phytoestrogen genistein were able to increase SF-1 transcription, promote Ishikawa cell proliferation, and induce the SF-1 target gene aromatase in a GPR30-dependent manner. Our findings suggest a novel signaling paradigm that is initiated by estrogen activation of the 7TM receptor GPR30, with signal transduction cascades (PI3K and MAPK) converging on nuclear hormone receptors (SF-1/LRH-1) to modulate their transcriptional output. We propose that this novel GPR30/SF-1 pathway increases local concentrations of estrogen, and together with classic ER signaling, mediate the proliferative effects of synthetic estrogens such as tamoxifen, in promoting endometriosis and endometrial cancers.

Estrogen and its receptors in cancer

The involvement of estrogen and its receptors in the development of cancer has been known for years. However, the exact mechanism responsible is far from clear. The estrogen-mediated carcinogenic process is complicated by recent findings, which reveal that estrogens have multiple functions in cells, which can be either adverse or beneficial, and that the effects of estrogen may be cell-type or organ dependent. The estrogenic effect may be also greatly influenced by the state of two estrogen receptors, ERalpha and ERbeta. This review will discuss the role and function of estrogens and its receptors in cancers of three categories: (1) Breast cancer and gynecologic cancers, (2) Cancers of endocrine organs, (3) Lung cancer and cancers of digestive system. We will also review some novel treatments aiming to interfere with relevant pathways mediated by estrogens and its receptors.