Breast cancer chemoprevention: current challenges and a look toward the future

Nipple Aspirate Fluid at a Glance

Simple Summary

Nipple aspirate fluid (NAF) is a promising source of markers for detection of breast cancer. NAF can be acquired via the nipple by aspiration using a suction device, which is well tolerated by women. Future possible applications of biomarkers for breast cancer derived from NAF could be (1) as a detection tool to identify the initiation of the cancer development process, (2) as an additional tool next to imaging (mammography and breast magnetic resonance imaging) or (3) as a replacement tool for when imaging is not advisable for women, such as during pregnancy and breastfeeding. With this paper, we present a narrative review and perspectives of NAF research at a glance.

Abstract

Nipple aspirate fluid (NAF) is an intraductal mammary fluid that, because of its close proximity to and origin from the tissue from which breast cancer originates, is a promising source of biomarkers for early breast cancer detection. NAF can be non-invasively acquired via the nipple by aspiration using a suction device; using oxytocin nasal spray helps increase yield and tolerability. The aspiration procedure is generally experienced as more tolerable than the currently used breast imaging techniques mammography and breast magnetic resonance imaging. Future applications of NAF-derived biomarkers include their use as a tool in the detection of breast carcinogenesis at its earliest stage (before a tumor mass can be seen by imaging), or as a supporting diagnostic tool for imaging, such as when imaging is less reliable (to rule out false positives from imaging) or when imaging is not advisable (such as during pregnancy and breastfeeding). Ongoing clinical studies using NAF samples will likely shed light on NAF’s content and clinical potential. Here, we present a narrative review and perspectives of NAF research at a glance.

The membrane-linked adaptor FRS2β fashions a cytokine-rich inflammatory microenvironment that promotes breast cancer carcinogenesis

Human breast cancer develops after a long period of latency under premalignant conditions. Strategies to target the premalignant conditions have yet to materialize since the molecular mechanisms remain obscure. Here, we discovered that FRS2β, expressed in a subset of mammary epithelial cells, directly activates nuclear factor–κB (NF-κB) and drives the initiation and promotion of the stroma-rich premalignant conditions. The FRS2β-triggered activation of NF-κB takes place in the early endosomes, the organelles, which have not been believed to be a major place for NF-κB signaling. The endosome signaling should be a novel focus for targeting therapy for prevention of breast cancer. This work paves a new way to develop preventive strategies of breast tumor development.

Although it is held that proinflammatory changes precede the onset of breast cancer, the underlying mechanisms remain obscure. Here, we demonstrate that FRS2β, an adaptor protein expressed in a small subset of epithelial cells, triggers the proinflammatory changes that induce stroma in premalignant mammary tissues and is responsible for the disease onset. FRS2β deficiency in mouse mammary tumor virus (MMTV)–ErbB2 mice markedly attenuated tumorigenesis. Importantly, tumor cells derived from MMTV-ErbB2 mice failed to generate tumors when grafted in the FRS2β-deficient premalignant tissues. We found that colocalization of FRS2β and the NEMO subunit of the IκB kinase complex in early endosomes led to activation of nuclear factor–κB (NF-κB), a master regulator of inflammation. Moreover, inhibition of the activities of the NF-κB–induced cytokines, CXC chemokine ligand 12 and insulin-like growth factor 1, abrogated tumorigenesis. Human breast cancer tissues that express higher levels of FRS2β contain more stroma. The elucidation of the FRS2β–NF-κB axis uncovers a molecular link between the proinflammatory changes and the disease onset.

Assessing intraepithelial neoplasia and drug safety in cancer-preventive drug development

Despite significant interest from the research community and the population in general, drug approvals for cancer prevention and/or cancer risk reduction are few. This is due, in part, to the requirement that new cancer-preventive drugs must first be shown to be efficacious in reducing cancer incidence or mortality. Moreover, such drugs need to have proven safety for long-term administration. This process can be improved by focusing on precancer (intraepithelial neoplasia) to identify subjects at risk and prove efficacy in shorter, smaller trials as well as on detecting early markers of potential toxicities of chronic exposure to cancer-preventive drug regimens.

Assessing breast tissue density by transillumination breast spectroscopy (TIBS): an intermediate indicator of cancer risk

Risk assessment by parenchymal density pattern, a strong physical indicator of future breast cancer risk, is available with the onset of mammographic screening programmes. However, due to the use of ionizing radiation, mammography is not recommended for use in younger women, thereby rendering risk assessment unattainable at an earlier age. Visible and near infrared light was used on 292 women with radiologically normal mammograms to determine whether transillumination breast spectroscopy (TIBS) can identify women with a high parenchymal density pattern as an intermediate indicator of breast cancer risk. Principal component analysis (PCA) was used to reduce the spectral data and generate density scores for each woman. To assess the accuracy of TIBS, logistic regression was used to calculate crude and adjusted odds ratios (OR) and 95% confidence intervals (CI) for each score. Receiver operator characteristic (ROC) curves and area under the curve (AUC) were also calculated for the crude and adjusted logistic models. Optical information relating to tissue chromophores, such as water, lipid and haemoglobin content, was sufficient to identify women with high parenchymal density. The resulting AUC for the final and most parsimonious multivariate logistic model was 0.922 (95% CI 0.878-0.967). TIBS provides information correlating to high parenchymal density and is a promising tool for risk assessment, particularly for younger women.

Progress in chemoprevention drug development: the promise of molecular biomarkers for prevention of intraepithelial neoplasia and cancer--a plan to move forward

This article reviews progress in chemopreventive drug development, especially data and concepts that are new since the 2002 AACR report on treatment and prevention of intraepithelial neoplasia. Molecular biomarker expressions involved in mechanisms of carcinogenesis and genetic progression models of intraepithelial neoplasia are discussed and analyzed for how they can inform mechanism-based, molecularly targeted drug development as well as risk stratification, cohort selection, and end-point selection for clinical trials. We outline the concept of augmenting the risk, mechanistic, and disease data from histopathologic intraepithelial neoplasia assessments with molecular biomarker data. Updates of work in 10 clinical target organ sites include new data on molecular progression, significant completed trials, new agents of interest, and promising directions for future clinical studies. This overview concludes with strategies for accelerating chemopreventive drug development, such as integrating the best science into chemopreventive strategies and regulatory policy, providing incentives for industry to accelerate preventive drugs, fostering multisector cooperation in sharing clinical samples and data, and creating public-private partnerships to foster new regulatory policies and public education.

Lifestyle and medical approaches to cancer prevention

Cancer risk can be reduced by adopting a healthy lifestyle and by medical means. Tobacco control is central to public policies for cancer prevention. Overweight and obesity in the United States may contribute to 20% of cancer deaths in women and 14% in men. Cancer prevention strategies have progressed from a predominant lifestyle approach to a model that combines clinical investigations in a medical setting with public health interventions. This change stems from advances in identifying, developing, and testing agents with the potential either to prevent cancer initiation, or to inhibit or reverse the progression of premalignant lesions to invasive cancer. Encouraging laboratory and epidemiologic studies, along with secondary endpoints in treatment trials, have provided a strong scientific rationale for the hypothesis that a pharmacologic approach--chemoprevention--can reduce cancer risk. Numerous chemopreventive agents, including naturally occurring vitamins, minerals, phytochemicals, and synthetic compounds, have proved to be safe and effective in preclinical and clinical studies. Promising results have been reported for cancers of the prostate, breast, colon, lung, bladder, cervix, oral cavity, esophagus, skin, and liver. The use of emerging technologies, identification of biomarkers of risk, and advances in genetic research are being applied to chemoprevention research. An interdisciplinary research approach to investigate molecular and genetic markers--as well as chemoprevention and lifestyle strategies--that affect cancer risk is being applied to the most common types of cancer in the United States in women (breast) and men (prostate).

Ductal lavage of fluid-yielding and non-fluid-yielding ducts in BRCA1 and BRCA2 mutation carriers and other women at high inherited breast cancer risk

OBJECTIVE

Nipple fluid production and atypical breast duct cells in women at high risk of breast cancer have been associated with further increased risk. Most publications on ductal lavage for cell collection report cannulating fluid-yielding ducts only. We report lavage of fluid-yielding and non-fluid-yielding ducts in women at high inherited breast cancer risk.

METHODS

A pilot breast cancer screening study including ductal lavage was conducted in 75 women at high inherited risk, 56 (74.7%) of whom had BRCA1/2 mutations. Ductal lavage was attempted in any duct identifiable with a catheter.

RESULTS

Ducts were successfully catheterized in 60 of 75 patients (80%). Successfully catheterized patients were younger (median age 41 versus 53 years, P = 0.0003) and more often premenopausal (51.7% versus 20%, P = 0.041). Thirty-one successfully catheterized patients [51.6%, 95% confidence interval (39.4-63.9%)] had non-fluid-yielding ducts only. Seventeen patients [28.3% (18.5-40.9%)] had atypical cells. Twelve of seventeen [70.6% (46.8-87.2%)] samples with atypia were from non-fluid-yielding ducts. Patients with non-fluid-yielding ducts (versus fluid-yielding ducts) were more likely to have had prior cancer (48.4% versus 17.2%, P = 0.014) or chemotherapy (45.2% versus 17.2%, P = 0.027); this was also true in patients with atypia from non-fluid-yielding ducts.

CONCLUSION

Successfully lavaged women were younger and more often premenopausal. Atypical cells can be found in non-fluid-yielding ducts in patients at high inherited breast cancer risk. Non-fluid-yielding ducts, and atypia from non-fluid-yielding ducts, are more common in patients with prior cancer and chemotherapy. Larger studies are needed to identify risk factors and prognostic significance associated with atypia and non-fluid-yielding ducts in high-risk populations, and define their role as biomarkers.

Secretome analysis of microarray data reveals extracellular events associated with proliferative potential in a cell line model of breast disease

It is widely believed that breast cancer develops in a multistep process with premalignant lesions preceding invasive carcinoma. The characterization of molecular events associated with premalignant progression would improve our understanding of carcinogenesis and greatly benefit the development of early detection methods and chemoprevention strategies. However, the molecular biology of precancerous breast disease is poorly understood. To better characterize extracellular events associated with disease progression, such as cell-cell and cell-extracellular matrix (ECM) signaling, we analyzed gene expression profiles for the set of genes coding for secreted proteins (the secretome) in a cell line model of human proliferative breast disease (PBD). PBD describes a series of preneoplastic changes in the inner lining of milk glands associated with a dramatic increase in the risk of breast cancer. We used a series of cell lines with increasing proliferative propensity, and cell cultures were grown on matrigel to emulate in vivo growth and ECM interactions. Microarray analysis identified two clusters of secretome genes with expression profiles correlating to PBD progression. Some of the identified genes have previously been associated with breast malignancies, and our results suggest that changes in expression for these genes begin in the premalignant stage, offering potential use for early detection and as chemotherapeutic targets. RT-PCR validation demonstrates the reliability of the microarray results.

Failure of high risk women to produce nipple aspirate fluid does not exclude detection of cytologic atypia in random periareolar fine needle aspiration specimens

INTRODUCTION

Evidence of hyperplasia with atypia found both on random periareolar fine needle aspiration (RPFNA) and in nipple aspirate fluid (NAF) fluid are associated with an increased risk for breast cancer.

AIM

In this study, we report the correlation of NAF production with cytological assessment of ductal cells obtained by RPFNA.

METHODS

113 women at high risk for development of breast cancer attending the Breast Cancer Prevention Clinic at the University of Kansas Medical Center underwent a single NAF collection attempt and RPFNA.

RESULTS

NAF was successfully collected in 51% of women. There was no significant difference in age, 5-year Gail risk assessment, menopausal status, hormone use, family history of breast cancer, history of prior atypical hyperplasia/LCIS or history of contralateral DCIS/invasive breast cancer between women who produced NAF and those that did not. The only significant difference between the two groups was in history of prior lactation (p = 0.018). Twenty-seven of the 113 subjects were found to have hyperplasia with atypia by RPFNA was 31% in women who produced NAF versus 16% in those who did not (p = 0.07).

CONCLUSION

Although prevalence of RPFNA atypia was numerically higher in NAF producers than non-producers the difference did not reach statistical significance. Failure to produce NAF does not exclude the presence of hyperplasia with atypia by random periareolar fine needle aspiration.

Protein biomarkers for breast cancer prevention

Protein biomarkers suitable for the prevention of breast cancer must be extremely sensitive, easily detectable and highly correlated with the disease. They should be expressed in the reversible phase of carcinogenesis. Among the large number of candidate tumour-associated proteins, those related to the oestrogen/chorionic gonadotropin/insulin pathway seem to be of most interest because these can be causally implicated. They presumably are the first to express differently and are open to hormonal treatments. The biomarkers that give information on membrane receptor-modulated signal transduction should be considered as well. Up to now, only tamoxifen has shown some preventive activity, suggesting that the oestrogen pathway is useful indeed. Fenretinide and recombinant human chorionic gonatotropin (hCG) are also promising. But the financial requirements and the very long assessment periods largely prevent current research. This is precisely why we badly need to give priority to molecular biology research, in particular in the protein compartment There is widespread belief that advanced proteomics together with increased informatics can provide specific combinations of disease-related expression profiles that could identify high-risk groups with much more reliability and allow us to monitor preventive strategies.

A Pilot Surrogate End Point Biomarker Trial of Perillyl Alcohol in Breast Neoplasia

PURPOSE

Efficient strategies to screen promising agents in early phase development are essential for rapid progress in breast cancer chemoprevention. We report our experience with the natural compound perillyl alcohol (POH) administered in a short-term surrogate end point biomarker (SEB) protocol, using the "window" between diagnostic and definitive surgery.

EXPERIMENTAL DESIGN

Eligible patients included those with a diagnosis of atypical ductal hyperplasia, ductal carcinoma in situ, lobular carcinoma in situ, or invasive carcinoma (<3 cm in size) that required further surgery. Thirty-seven of 267 women screened were enrolled in the study (14%). Five women received single-dose POH (1.5 g/m2) 2 days before surgery, 16 received escalating doses of POH (1.2 g/m2 to 4.8 g/m2/day) for 2 days before surgery, and 16 served as untreated controls. Exploratory SEB analysis [estrogen receptor, progesterone receptor, proliferation, apoptosis, M6P/insulin-like growth factor (IGF)-2R, IGF1, IGF2 and transforming growth factor beta] was conducted before and after POH.

RESULTS

Only a small portion of the population screened entered the study. Reasons for nonparticipation included protocol ineligibility, conflict of timing of surgery, miscellaneous logistical reasons, or patient's choice. POH administration was well tolerated and did not interfere with surgical management. The power to observe changes in candidate SEB was diminished by a 44% incidence of cases in which the index lesion was not present in the definitive surgical specimen.

CONCLUSIONS

Preoperative POH exposure was safe and suitable for a more definitive phase II SEB study. Further investigations must overcome logistical obstacles to accrual, and they must focus on approaches to maximize tissue collection and to incorporate genomic analysis of target lesions.

Hormones and mammographic breast density

Mammographic density reveals information about the hormonal environment along with the heritability in which breast cancer develops. This is made possible by the widespread use of population screening by mammography. Increasingly this is an important observation not just for population studies, which reveal disease determinants, but also for the individual. Density reveals the effect of the intrinsic hormonal environment and its background genetics, and also the effect of pharmaceuticals--agents used for disease control and prevention and hormone replacement therapy (HRT) used for well-being around the menopause. Increasingly this focus on the individual will need methods of measurement of density that can be monitored with greater accuracy than the widely used BI-RADS 4 categories. For this purpose studies are under way to measure volume of dense tissue as a continuous variable. In due course, measurement of density will be used as a biomarker of risk, employed in risk models and to monitor interventions. Before this can happen more knowledge will be needed of the change occurring naturally through the menopause and the differences between individuals. This will need specific study backed up with detailed information about the patient on large numbers of women and their mammograms. Currently the widespread use of HRT has increased the prevalence of the dense patterns and potentially may adversely affect the effectiveness of mammographic screening programmes. There is a large literature recording this from which we see that combined continuous preparations of oestrogen progestin are more likely to cause increased density than oestrogen alone or tibolone. Breast density, measured more accurately, has the potential to be an important adjunct to risk estimation and to monitor interventions for breast cancer prevention with pharmaceuticals (such as SERMS) and by change in lifestyle behaviours.

Applying the neoadjuvant paradigm to ductal carcinoma in situ

Local treatment options for ductal carcinoma in situ (DCIS) are virtually identical to those for early invasive breast cancer, despite the fact that the survival from this condition is much higher. Our ability to more appropriately tailor therapy for DCIS is hampered by a lack of understanding of the natural history of DCIS, our limited ability to predict the rate of progression to invasive cancer and the response to therapy, and the absence of tools to follow patients who have not had invasive treatments. Neoadjuvant therapy, which has been proven to be both safe and effective in tailoring treatments for invasive cancer, could be ideally suited to DCIS. However, neoadjuvant therapy requires that doctors and patients delay surgical treatment that has known benefits. In order to successfully introduce this approach into clinical practice, risk assessment and decision support tools will be needed to help physicians and patients feel comfortable that they are not being exposed to unnecessary or excessive risk. In addition, we need better imaging to track extent and progression of disease. Among the possible benefits of the neoadjuvant approach, we may discover that many lesions are responsive and some even reversible, leaving us with treatments that might be tailored to biology and with important clues for breast cancer prevention in high-risk women.

Physician recommendations regarding tamoxifen and patient utilization of tamoxifen after surgery for ductal carcinoma in situ

BACKGROUND

To date, the impact of the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-24 trial reported in 1999 on the use of tamoxifen after surgery for ductal carcinoma in situ (DCIS) is unknown. The current study was designed to evaluate the impact of NSABP B-24 on current practices at a comprehensive cancer center.

METHODS

The records of 350 consecutive patients with DCIS who were treated at the authors' institution between July 1999 and June 2002 were obtained from a prospective database and analyzed. Whether patients were offered tamoxifen, whether patients accepted tamoxifen, and the associated reasons were recorded along with tamoxifen-related side effects and patient compliance with therapy. Clinical and pathologic factors were evaluated for their impact on recommendations regarding tamoxifen. Differences were assessed by chi-square analysis.

RESULTS

Of the 350 patients, 73 were excluded because of evidence of invasive carcinoma on final pathology review. Of the remaining 277 patients, 166 patients (60%) were offered tamoxifen, and 90 patients (54%) chose to take tamoxifen. Of 111 patients who were not offered tamoxifen, 39 patients (35%) had documented explanations, which included bilateral mastectomy (n = 25 patients), medical reasons (n = 10 patients), and already received tamoxifen for other reasons at the time of diagnosis (n = 4 patients). Of 94 patients who received tamoxifen, 20 patients (21%) discontinued use because of side effects or complications. Tamoxifen was more likely to be recommended for women who underwent segmental resection compared with women who underwent total mastectomy (P = 0.002) and for women with smaller pathologic DCIS tumors (P = 0.001). In addition, these two factors were interrelated.

CONCLUSIONS

Physicians and patients remain cautious regarding the use of tamoxifen after local treatment for DCIS. The current findings have implications for current trials evaluating aromatase inhibitors and other chemopreventive agents for this disease.

Use of exfoliated cells from target tissues to predict responses to bioactive food components

A host of bioactive food components have been proposed to promote health and reduce the risk of disease states. It is clear that not all individuals respond identically to these essential and nonessential food components. Genetic polymorphisms may influence absorption, metabolism and accumulation of bioactive food components, thereby influencing their actions in target tissues. Unfortunately, serum concentrations of bioactive food components may not correlate with tissue concentrations and may therefore under- or overestimate the response in target tissues. Exfoliated cells may be useful to assess the actions of nutrients in specific tissues. Although not extensively examined, evidence already suggests the usefulness of these cells in predicting changes in gene expression, DNA methylation, DNA damage, protein expression and accumulation of dietary components. Although there are limitations on the collection of exfoliated cells, the inaccessibility of tissues they can represent raises intriguing possibilities for their ability to predict the outcome of nutritional intervention studies.

Anti-oestrogenic chemoprevention of breast cancer-the need to progress

Clinical trials of the selective oestrogen receptor modulator (SERM), tamoxifen, have shown an early reduction in risk of breast cancer in healthy women of approximately 40%, but with associated risks and benefits to normal tissues. An overall clinical benefit and the identification of the women at risk of breast cancer who may gain benefit from tamoxifen has not been clearly established. The identification of those women at risk who are most likely to gain benefit, and the development of other SERMs and aromatase inhibitors which might be more active and have a more beneficial spectrum of activity on normal tissues in healthy women is essential, if the aim of preventing breast cancer in healthy women is to be achieved.

Anti-oestrogenic prevention of breast cancer--the make or break point

Clinical trials have shown that giving anti-oestrogens to healthy women can reduce the early incidence of breast cancer by approximately 40%. However, the large numbers of women treated, compared with the few who get breast cancer, together with the not insignificant toxicity and the unknown long-term clinical benefits and risks, makes this strategy of prevention versus treatment precarious. So how can we improve the odds for the successful use of endocrine chemoprevention?