Endocrine Therapy for Leptomeningeal Metastases from ER-Positive Breast Cancer: Case Report and a Review of the Literature.

Leptomeningeal disease is an uncommon complication of estrogen receptor positive breast cancer. While there is little consensus on the standard of care, recommendations from current clinical practice guidelines are to treat with intrathecal chemotherapy, necessitating invasive procedures and potentially resulting in a substantial incidence of serious complications and side effects. Here, we review all published evidence of the effectiveness of systemic hormonal therapy alone in treating this condition, with the advantage of requiring no invasive procedures and having virtually no serious complications or side effects. Evidence indicates that most hormonal therapies can penetrate the central nervous system and can be an effective treatment of endocrine sensitive breast cancer that is widely metastatic to the leptomeninges.

A phase II trial of capecitabine concomitantly with whole-brain radiotherapy followed by capecitabine and sunitinib for brain metastases from breast cancer.

BACKGROUND: Brain metastasis from breast cancer presents a significant threat to women's health and quality of life. Capecitabine and sunitinib have shown some activity in this setting; therefore, we conducted a single-arm phase II trial with these agents. METHODS: Patients with breast cancer and central nervous system (CNS) metastases received whole-brain radiotherapy concurrently with capecitabine (1,000 mg/m(2) per day for 14 consecutive days), followed by concomitant capecitabine (2,000 mg/m(2) per day for 2 weeks followed by a 1-week break) and sunitinib (37.5 mg daily, continuously). The primary endpoint was progression-free survival (PFS). RESULTS: Of 25 planned patients that would be required to detect a 4-month improvement (from 5 to 9 months) in median PFS with 80% power, 12 were enrolled, and the study was then closed for slow accrual. Median PFS was 4.7 months, and median overall survival was 10 months. In the CNS, 25% had progressive disease, and 83% experienced extra-CNS progression. The most common side effects were fatigue and nausea. CONCLUSION: In 12 evaluable patients studied, concurrent capecitabine and whole-brain radiation followed by capecitabine and sunitinib did not extend PFS over historical rates and was associated with significant toxicity. Our study was small and closed due to slow accrual.

A phase II study of combined fulvestrant and everolimus in patients with metastatic estrogen receptor (ER)-positive breast cancer after aromatase inhibitor (AI) failure.

Fulvestrant, which degrades ER, is used after AI failure in metastatic breast cancer but resistance develops quickly. We hypothesized that using everolimus to inhibit mTOR, a key signaling pathway in endocrine resistance, may delay fulvestrant resistance in patients and thus improve its efficacy. We conducted a phase II trial of combined fulvestrant and everolimus in postmenopausal women with disease progression or relapse after an AI. Primary endpoint was time to progression (TTP) and secondary endpoints included objective response rate, clinical benefit rate (CBR), safety, and biomarker correlates. Tumor blocks were collected and biopsy of accessible tumor was done for future biomarker analysis. Of 33 patients enrolled two were ruled ineligible after enrollment and were excluded from study analysis, for a total of 31 evaluable patients. Median age was 54 years (range 45-85). Prior therapy included tamoxifen (81 %), chemotherapy (71 %), with 26 % of patients having received 3 or more endocrine agents. Median TTP was 7.4 months (95 % CI 1.9-12.1) with an objective response rate of 13 % and CBR of 49 %. Of particular note, 32 % of patients exhibited de novo resistance to study treatment with disease progression as their best response. Most common adverse events (AEs) were elevated AST (87 %) and ALT (77 %), anemia (74 %), hyperglycemia (71 %), and hypercholesterolemia (68 %). Prominent clinical toxicities were mucositis (58 %), weight loss (48 %), and rash (42 %). Most AEs were grade 1 or 2 and largely reversible with infrequent need for everolimus dose reduction. To conclude, everolimus plus fulvestrant is effective after AI failure in heavily pretreated metastatic ER-positive breast cancer and has manageable toxicity. Further study of this combination is warranted in randomized studies. Since not all patients experience benefit, and in view of potential toxicities, biomarker examination is critical to help select patients most likely to benefit from this strategy in future studies.

BRCA1 deficiency in mature CD8+ T lymphocytes impairs antitumor immunity.

Women with BRCA1 germline mutations have approximately an 80% lifetime chance of developing breast cancer. While the tumor suppressor function of BRCA1 in breast epithelium has been studied extensively, it is not clear whether BRCA1 deficiency in non-breast somatic cells also contribute to tumorigenesis. Here, we report that mouse Brca1 knockout (KO) in mature T lymphocytes compromises host antitumor immune response to transplanted syngeneic mouse mammary tumors. T cell adoptive transfer further corroborates CD8+ T cell-intrinsic impact of Brca1 KO on antitumor adaptive immunity. T cell-specific Brca1 KO mice exhibit fewer total CD8+, more exhausted, reduced cytotoxic, and reduced memory tumor-infiltrating T cell populations. Consistent with the preclinical data, cancer-free BRCA1 mutation-carrying women display lower abundance of circulating CD8+ lymphocytes than the age-matched control group. Thus, our findings support the notion that BRCA1 deficiency in adaptive immunity could contribute to BRCA1-related tumorigenesis. We also suggest that prophylactic boosting of adaptive immunity may reduce cancer incidence among at-risk women.

Pathologic changes in breast cancer after anti-estrogen therapy.

Breast cancer patients do not commonly receive anti-estrogens prior to surgical excision. We reviewed a cohort of patients who received preoperative anti-estrogen therapy after baseline biopsy and then had a repeat biopsy after several weeks on treatment. Patients with estrogen receptor positive tumors received anastrozole and fulvestrant in combination with gefitinib. Core needle biopsies were performed at day 1 and 21, and tumors were completely excised if operable at day 112. All patients were postmenopausal. Following treatment, tumors had degenerative changes including smudged nuclei, decreased nuclear size, intranuclear vacuoles, vacuolated cytoplasm, and increased cellular discohesion. In addition, increased tubule formation and intracytoplasmic lumina were seen in 6/9 cases (66.7%) and decreased mitotic rate was demonstrated in 7/9 cases (77.8%). These findings indicate increased differentiation of the tumor cells in response to anti-estrogen therapy and that may correlate with clinical response.

A phase II neoadjuvant trial of anastrozole, fulvestrant, and gefitinib in patients with newly diagnosed estrogen receptor positive breast cancer.

Endocrine therapy in patients with breast cancer can be limited by the problem of resistance. Preclinical studies suggest that complete blockade of the estrogen receptor (ER) combined with inhibition of the epidermal growth factor receptor can overcome endocrine resistance. We tested this hypothesis in a phase II neoadjuvant trial of anastrozole and fulvestrant combined with gefitinib in postmenopausal women with newly diagnosed ER-positive breast cancer. After a baseline tumor core biopsy, patients were randomized to receive anastrozole and fulvestrant or anastrozole, fulvestrant, and gefitinib (AFG) for 3 weeks. After a second biopsy at 3 weeks, all patients received AFG for 4 months and surgery was done if the tumor was operable. The primary endpoint was best clinical response by RECIST criteria and secondary endpoints were toxicity and change in biomarkers. The study closed after 15 patients were enrolled because of slow accrual. Median patient age was 67 years and median clinical tumor size was 7 cm. Four patients had metastatic disease present. Three patients withdrew before response was assessed. In the remaining 12 patients, there were two complete clinical responses (17%), three partial responses (25%), five had stable disease (41%), and two (17%) had progressive disease. Most common adverse events were rash in four patients, diarrhea in four, joint symptoms in three, and abnormal liver function tests in three. There were no grade 4 toxicities and all toxicities were reversible. At 3 weeks, cell proliferation as measured by Ki-67 was significantly reduced in the AFG group (P value = 0.01), with a parallel reduction in the expression of the Cyclin D1 (P value = 0.02). RNA microarray data showed a corresponding decrease in the expression of cell cycle genes. These results suggest that AFG was an effective neoadjuvant therapy and consistently reduced proliferation in ER-positive tumors.

Self-blame, self-forgiveness, and spirituality in breast cancer survivors in a public sector setting.

Cognitive appraisal affects adjustment to breast cancer. A self-forgiving attitude and spirituality may benefit breast cancer survivors who blame themselves for their cancer. One hundred and eight women with early breast cancers completed questionnaires assessing self-blame, self-forgiveness, spirituality, mood and quality of life (QoL) in an outpatient breast clinic. Women who blamed themselves reported more mood disturbance (p < 0.01) and poorer QoL (p < 0.01). Women who were more self-forgiving and more spiritual reported less mood disturbance and better QoL (p's < 0.01). Interventions that reduce self-blame and facilitate self-forgiveness and spirituality could promote better adjustment to breast cancer.

ERα-related chromothripsis enhances concordant gene transcription on chromosome 17q11.1-q24.1 in luminal breast cancer.

BACKGROUND: Chromothripsis is an event of genomic instability leading to complex chromosomal alterations in cancer. Frequent long-range chromatin interactions between transcription factors (TFs) and targets may promote extensive translocations and copy-number alterations in proximal contact regions through inappropriate DNA stitching. Although studies have proposed models to explain the initiation of chromothripsis, few discussed how TFs influence this process for tumor progression. METHODS: This study focused on genomic alterations in amplification associated regions within chromosome 17. Inter-/intra-chromosomal rearrangements were analyzed using whole genome sequencing data of breast tumors in the Cancer Genome Atlas (TCGA) cohort. Common ERα binding sites were defined based on MCF-7, T47D, and MDA-MB-134 breast cancer cell lines using univariate K-means clustering methods. Nanopore sequencing technology was applied to validate frequent rearrangements detected between ATC loci on 17q23 and an ERα hub on 20q13. The efficacy of pharmacological inhibition of a potentially druggable target gene on 17q23 was evaluated using breast cancer cell lines and patient-derived circulating breast tumor cells. RESULTS: There are five adjoining regions from 17q11.1 to 17q24.1 being hotspots of chromothripsis. Inter-/intra-chromosomal rearrangements of these regions occurred more frequently in ERα-positive tumors than in ERα-negative tumors. In addition, the locations of the rearrangements were often mapped within or close to dense ERα binding sites localized on these five 17q regions or other chromosomes. This chromothriptic event was linked to concordant upregulation of 96 loci that predominantly regulate cell-cycle machineries in advanced luminal tumors. Genome-editing analysis confirmed that an ERα hub localized on 20q13 coordinately regulates a subset of these loci localized on 17q23 through long-range chromosome interactions. One of these loci, Tousled Like Kinase 2 (TLK2) known to participate in DNA damage checkpoint control, is an actionable target using phenothiazine antipsychotics (PTZs). The antiproliferative effect of PTZs was prominent in high TLK2-expressing cells, compared to low expressing cells. CONCLUSION: This study demonstrates a new approach for identifying tumorigenic drivers from genomic regions highly susceptible to ERα-related chromothripsis. We found a group of luminal breast tumors displaying 17q-related chromothripsis for which antipsychotics can be repurposed as treatment adjuncts.

Association of surgery with improved survival in stage IV breast cancer patients.

OBJECTIVE: This study aims to examine the role of surgery in patients with stage IV breast cancer. BACKGROUND: Historically, women who present with metastatic breast cancer are not offered surgical treatment. However, recent reports indicate that surgery may improve outcome. Using a large database of women whom presented with stage IV breast cancer, we compared outcome of patients who had resection of their primary cancer to those who did not. METHODS: Of 16,401 patients, 807 had stage IV disease at presentation, and 395 survived >90 days and were included in this analysis. Clinical and tumor characteristics, surgical treatment, and survival were compared for the surgically versus nonsurgically treated patients. RESULTS: Two hundred and forty-two patients (61.3%) had definitive surgery for their primary tumor and 153 (38.7%) did not. Patients who underwent surgery were significantly older, were more likely to be white, more often had hormone receptor positive disease, had small primary tumors, and had fewer metastatic sites and less visceral involvement. The median survival of surgically treated patients was 27.1 months versus 16.8 months for patients without surgical resection (P < 0.0001). In multivariate analysis, which included surgical treatment, age, race, estrogen and progesterone receptor status, number of metastatic sites, and presence of visceral metastases, surgery remained an independent factor associated with improved survival (P = 0.006). CONCLUSION: Patients with stage IV breast cancer who had definitive surgical treatment of their primary tumors had more favorable disease characteristics. However, after adjustment for these characteristics, surgical treatment remained an independent factor associated with improved survival.

Imaging of lymph flow in breast cancer patients after microdose administration of a near-infrared fluorophore: feasibility study.

PURPOSE: To prospectively demonstrate the feasibility of using indocyanine green, a near-infrared (NIR) fluorophore at the minimum dose needed for noninvasive optical imaging of lymph nodes (LNs) in breast cancer patients undergoing sentinel lymph node mapping (SLNM). MATERIALS AND METHODS: Informed consent was obtained from 24 women (age range, 30-85 years) who received intradermal subcutaneous injections of 0.31-100 microg indocyanine green in the breast in this IRB-approved, HIPAA-compliant, dose escalation study to find the minimum microdose for imaging. The breast, axilla, and sternum were illuminated with NIR light and the fluorescence generated in the tissue was collected with an NIR-sensitive intensified charged-coupled device. Lymphoscintigraphy was also performed. Resected LNs were evaluated for the presence of radioactivity, blue dye accumulation, and fluorescence. The associations between the resected LNs that were fluorescent and (a) the time elapsed between NIR fluorophore administration and resection and (b) the dosage of NIR fluorophores were tested with the Spearman rank and Pearson product moment correlation tests, respectively. RESULTS: Lymph imaging consistently failed with indocyanine green microdosages between 0.31 and 0.77 microg. When indocyanine green dosages were 10 microg or higher, lymph drainage pathways from the injection site to LNs were imaged in eight of nine women; lymph propulsion was observed in seven of those eight. When propulsion in the breast and axilla regions was present, the mean apparent velocities ranged from 0.08 to 0.32 cm/sec, the time elapsed between "packets" of propelled fluid varied from 14 to 92 seconds. In patients who received 10 microg of indocyanine green or more, a weak negative correlation between the fluorescence status of resected LNs and the time between NIR fluorophore administration and LN resection was found. No statistical association was found between the fluorescence status of resected LNs and the dose of NIR fluorophore. CONCLUSION: NIR fluorescence imaging of lymph function and LNs is feasible in humans at microdoses that would be needed for future molecular imaging of cancer-positive LNs.

Intrinsic apoptotic pathway activation increases response to anti-estrogens in luminal breast cancers.

Estrogen receptor-α positive (ERα+) breast cancer accounts for approximately 70-80% of the nearly 25,0000 new cases of breast cancer diagnosed in the US each year. Endocrine-targeted therapies (those that block ERα activity) serve as the first line of treatment in most cases. Despite the proven benefit of endocrine therapies, however, ERα+ breast tumors can develop resistance to endocrine therapy, causing disease progression or relapse, particularly in the metastatic setting. Anti-apoptotic Bcl-2 family proteins enhance breast tumor cell survival, often promoting resistance to targeted therapies, including endocrine therapies. Herein, we investigated whether blockade of anti-apoptotic Bcl-2 family proteins could sensitize luminal breast cancers to anti-estrogen treatment. We used long-term estrogen deprivation (LTED) of human ERα+ breast cancer cell lines, an established model of sustained treatment with and acquired resistance to aromatase inhibitors (AIs), in combination with Bcl-2/Bcl-xL inhibition (ABT-263), finding that ABT-263 induced only limited tumor cell killing in LTED-selected cells in culture and in vivo. Interestingly, expression and activity of the Bcl-2-related factor Mcl-1 was increased in LTED cells. Genetic Mcl-1 ablation induced apoptosis in LTED-selected cells, and potently increased their sensitivity to ABT-263. Increased expression and activity of Mcl-1 was similarly seen in clinical breast tumor specimens treated with AI + the selective estrogen receptor downregulator fulvestrant. Delivery of Mcl-1 siRNA loaded into polymeric nanoparticles (MCL1 si-NPs) decreased Mcl-1 expression in LTED-selected and fulvestrant-treated cells, increasing tumor cell death and blocking tumor cell growth. These findings suggest that Mcl-1 upregulation in response to anti-estrogen treatment enhances tumor cell survival, decreasing response to therapeutic treatments. Therefore, strategies blocking Mcl-1 expression or activity used in combination with endocrine therapies would enhance tumor cell death.

Author Correction: Attenuation of RNA polymerase II pausing mitigates BRCA1-associated R-loop accumulation and tumorigenesis.

This corrects the article DOI: 10.1038/ncomms15908.

Molecular heterogeneity of inflammatory breast cancer: a hyperproliferative phenotype.

PURPOSE: Inflammatory breast cancer (IBC) is associated with very poor prognosis. The aims of this study are (a) to prospectively identify differential gene expression patterns associated with IBC and (b) to confirm these pathways using tissue arrays. EXPERIMENTAL DESIGN: For gene expression analysis, IBC (n=14) was clinically defined as rapid-onset cancer associated with erythema and skin changes, whereas non-IBC patients (n=20) had stage III breast cancers, and cDNA analysis was carried out using the Affymetrix (Santa Clara, CA) HG-U133A microarrays. Tissue arrays were constructed from paraffin-embedded material, and the molecular phenotype of 75 IBC was compared with results from>2,000 non-IBC. RESULTS: Gene expression analyses indicated that IBC has higher expression of genes associated with increased metabolic rate, lipid signaling, and cell turnover relative to non-IBC tumors. Consistent with the expression analysis, IBC had statistically higher Ki-67 (93% versus 11%; P<0.001). BAX expression, reflecting increased apoptosis and cell turnover, was significantly uniformly higher in almost all IBC (98% versus 66%; P<0.05), whereas the expression of Bcl-2 was not significantly different. IBC tumors were more likely to be steroid hormone receptor negative (estrogen receptor, 49% versus 30%; P=0.002; progesterone receptor, 68% versus 42%; P=0.001). The expression of tyrosine kinases was not significantly different. E-cadherin was found to be expressed in 87% of IBC, whereas the expression p53 was not significantly different. CONCLUSION: This study is one of the largest molecular analyses of IBC. Both IBC and non-IBC are genetically heterogeneous with consistent differences in the molecular phenotype of IBC.

Attenuation of RNA polymerase II pausing mitigates BRCA1-associated R-loop accumulation and tumorigenesis.

Most BRCA1-associated breast tumours are basal-like yet originate from luminal progenitors. BRCA1 is best known for its functions in double-strand break repair and resolution of DNA replication stress. However, it is unclear whether loss of these ubiquitously important functions fully explains the cell lineage-specific tumorigenesis. In vitro studies implicate BRCA1 in elimination of R-loops, DNA-RNA hybrid structures involved in transcription and genetic instability. Here we show that R-loops accumulate preferentially in breast luminal epithelial cells, not in basal epithelial or stromal cells, of BRCA1 mutation carriers. Furthermore, R-loops are enriched at the 5' end of those genes with promoter-proximal RNA polymerase II (Pol II) pausing. Genetic ablation of Cobra1, which encodes a Pol II-pausing and BRCA1-binding protein, ameliorates R-loop accumulation and reduces tumorigenesis in Brca1-knockout mouse mammary epithelium. Our studies show that Pol II pausing is an important contributor to BRCA1-associated R-loop accumulation and breast cancer development.

Neoadjuvant trastuzumab induces apoptosis in primary breast cancers.

PURPOSE: Greater understanding of the cellular response in trastuzumab-treated patients will provide insight into the clinical management of patients. PATIENTS AND METHODS: We performed a neoadjuvant trial in 35 patients with locally advanced HER-2/neu overexpressing breast cancers who received weekly trastuzumab given as a single agent for the first 3 weeks, followed by a combination of trastuzumab and docetaxel for 12 weeks before surgery. Sequential core biopsies were taken at baseline and within weeks 1 and 3 after the first dose of trastuzumab. Clinical response to trastuzumab was assessed by tumor measurements on day 22 before chemotherapy. Core biopsies were assessed by immunohistochemistry for cell cycle and proliferation (Ki67, p27, phosphorylated [p] -MAPK), apoptosis and survival (apoptotic index, p-Akt), epidermal growth factor receptor, and total and p-HER-2. RESULTS: There was early tumor regression with a median decrease of -20.0% (range. 0% to 60.4%) after only 3 weeks of trastuzumab, and eight patients (23%) had a partial response. Consistent with the clinical regressions, apoptosis was significantly induced (median increase from 3.5% to 4.7%; P = .006) within week 1, a 35% increase above baseline. No significant change in epidermal growth factor receptor score was observed in week 1, without changes in total or p-HER-2 expression. Tumors with high baseline Ki67 were less likely to respond (P = .02). CONCLUSION: In primary breast cancers, trastuzumab substantially induces apoptosis, providing a molecular explanation for both its therapeutic efficacy and its successful combination with cytotoxic chemotherapy.

Patterns of resistance and incomplete response to docetaxel by gene expression profiling in breast cancer patients.

PURPOSE: Chemotherapy for operable breast cancer decreases the risk of death. Docetaxel is one of the most active agents in breast cancer, but resistance or incomplete response is frequent. PATIENTS AND METHODS: Core biopsies from 24 patients were obtained before treatment with neoadjuvant docetaxel (four cycles, 100 mg/m(2) every 3 weeks), and response was assessed after chemotherapy. After 3 months of neoadjuvant chemotherapy, surgical specimens (n = 13) were obtained, and laser capture microdissection (LCM; n = 8) was performed to enrich for tumor cells. From each core, surgical, and LCM specimen, sufficient total RNA (3 to 6 microg) was extracted for cDNA array analysis using the Affymetrix HgU95-Av2 GeneChip (Affymetrix, Santa Clara, CA). RESULTS: From the initial core biopsies, differential patterns of expression of 92 genes correlated with docetaxel response (P = .001). However, the molecular patterns of the residual cancers after 3 months of docetaxel treatment were strikingly similar, independent of initial sensitivity or resistance. This relative genetic homogeneity after treatment was observed in both LCM and non-LCM surgical specimens. The residual tumor after treatment in tumors that were initially sensitive indicates selection of a residual and resistant subpopulation of cells. The gene expression pattern was populated by genes involved in cell cycle arrest at G(2)M (eg, mitotic cyclins and cdc2) and survival pathways involving the mammalian target of rapamycin. CONCLUSION: A specific and consistent gene expression pattern was found in residual tumors after docetaxel treatment. These profiles provide therapeutic targets that could lead to improved treatment.

Long-term clinical response in leptomeningeal metastases from breast cancer treated with capecitabine monotherapy: a case report.

Brain and leptomeningeal metastases from breast cancer carry a poor prognosis and are often less responsive to systemic therapy. It is often thought that systemic therapy has a minimal role in the management of central nervous system (CNS) metastases because of the impermeability of the blood-brain barrier. However, treatments directed to the CNS such as radiation or intrathecal chemotherapy are not effective in managing concurrent non-CNS metastases. We report the long-term control of a woman receiving capecitabine with brain and leptomeningeal metastases. After 3.7 years of capecitabine therapy after whole-brain radiation, the patient remains without neurologic symptoms or deficits, has no evidence of disease on neuroimaging studies, but has a persistent positive cytology. This case report demonstrates that, in principle, systemic therapy can provide long-term complete responses for some patients with CNS metastases. The significance of persistent circulating tumor cells in the CNS in patients without evidence of disease is unclear but should be investigated further.

The adherence to practice guidelines in the assessment of bone health in women with chemotherapy-induced menopause.

Premenopausal women are diagnosed with 25% of all invasive breast cancers;adjuvant chemotherapy given to many of this population may induce menopause and increase the risk of osteoporosis development. Guidelines issued by the American Society of Clinical Oncology recommend regular assessment of bone health in such women. To assess appropriate attention to bone health, we performed a retrospective, cross-sectional survey of young women at high risk of osteoporosis secondary to chemotherapy-induced premature menopause. In all, 102 women with chemotherapy-induced menopause, 75% of whom were 40 years of age or younger, were asked whether they underwent screening and preventive measures for osteoporosis. Only 56% had discussed bone health with their healthcare providers; age at diagnosis, race, and use of tamoxifen were not linked to the likelihood of such discussions. Regular exercise was recommended to 73% of the women, calcium supplementation to 56%, and bone mineral density (BMD) testing to 40%. Approximately one half of the women regularly exercised and took a calcium supplement; however, over 37% of those using a supplement took less calcium than that recommended to prevent osteoporosis. Further, 32% reported having had BMD testing;women 40 years of age or younger were less likely to have had such tests (27%) than were older women (48%;P = 0.05). More emphasis must be given to educating breast cancer survivors with chemotherapy-induced menopause about bone health and its maintenance. Approved therapies to prevent osteoporosis probably are underused in this population.

Premalignant and in situ breast disease: biology and clinical implications.

Most types of invasive breast cancer are thought to evolve over long periods from specific preexisting benign lesions. Of the many types of benign entities found in the human breast, only a few have clinically significant premalignant potential. Currently, the best-characterized premalignant lesions are atypical ductal hyperplasia, atypical lobular hyperplasia, and lobular carcinoma in situ. Ductal carcinoma in situ is considered to be a preinvasive malignant lesion. Two additional lesions, unfolded lobules and usual ductal hyperplasia, are sometimes considered to be very early premalignant epithelial abnormalities. Premalignant lesions are currently defined by their histologic features, and not all necessarily progress to invasive cancer. This suggests that although lesions within specific categories look alike, they must possess underlying genetic differences that cause some to remain stable and others to advance. The development of modern molecular genetic techniques has allowed breast cancer researchers to clarify the multistep model of breast carcinogenesis. Recent studies indicate that cancer evolves by highly diverse genetic mechanisms, and research into these altered pathways may identify specific early defects that might be targeted to prevent progression of premalignant lesions to invasive cancer. Current clinical management is heterogeneous and depends on histologic examination and individual patient factors. Options for breast cancer risk reduction and prevention are available.

Tyrosine phosphorylation regulates ERß ubiquitination, protein turnover, and inhibition of breast cancer.

Unlike estrogen receptor α (ERα) that predominantly promotes hormone-dependent breast tumor growth, ERß exhibits antitumor effects in a variety of cancer types. We recently identified a phosphotyrosine residue in ERß, but not ERα, that dictates ERß transcriptional activity and antitumor function. We show here that this ER isotype-specific phosphotyrosine switch is important for regulating ERß activity in cell proliferation, migration, and invasion. At the mechanistic level, phosphorylated ERß, which recruits transcriptional coactivator p300, is in turn targeted by p300 for ubiquitination and proteasome-dependent protein turnover. Furthermore, ERß-specific agonists such as S-equol enhance ERß phosphorylation, suggesting a crosstalk between ligand- and posttranslational modification-dependent ERß activation. Inhibition of xenograft tumor growth by S-equol is associated with reduced tumor Ki-67 expression and elevated ERß tyrosine phosphorylation. Taken together, our data support the notion that phosphotyrosine-dependent ERß signaling is an attractive target for anticancer treatment.