Successful oxytocin-assisted nipple aspiration in women at increased risk for breast cancer

Extracting Knowledge from Machine Learning Models to Diagnose Breast Cancer

This study explored the application of explainable machine learning models to enhance breast cancer diagnosis using serum biomarkers, contrary to many studies that focus on medical images and demographic data. The primary objective was to develop models that are not only accurate but also provide insights into the factors driving predictions, addressing the need for trustworthy AI in healthcare. Several classification models were evaluated, including OneR, JRIP, the FURIA, J48, the ADTree, and the Random Forest, all of which are known for their explainability. The dataset included a variety of biomarkers, such as electrolytes, metal ions, marker proteins, enzymes, lipid profiles, peptide hormones, steroid hormones, and hormone receptors. The Random Forest model achieved the highest accuracy at 99.401%, followed closely by JRIP, the FURIA, and the ADTree at 98.802%. OneR and J48 achieved 98.204% accuracy. Notably, the models identified oxytocin as a key predictive biomarker, with most models featuring it in their rules. Other significant parameters included GnRH, β-endorphin, vasopressin, IRAP, and APB, as well as factors like iron, cholinesterase, the total protein, progesterone, 5-nucleotidase, and the BMI, which are considered clinically relevant to breast cancer pathogenesis. This study discusses the roles of the identified parameters in cancer development, thus underscoring the potential of explainable machine learning models for enhancing early breast cancer diagnosis by focusing on explainability and the use of serum biomarkers.The combination of both can lead to improved early detection and personalized treatments, emphasizing the potential of these methods in clinical settings. The identified markers also provide additional research and therapeutic targets for breast cancer pathogenesis and a deep understanding of their interactions, advancing personalized approaches to breast cancer management.

Early detection of breast cancer through the diagnosis of Nipple Aspirate Fluid (NAF)

The development of breast cancer has been mainly reported in women who have reached the post-menopausal stage; therefore, it is the primary factor responsible for death amongst postmenopausal women. However, if treated on time it has shown a survival rate of 20 years in about two-thirds of women. Cases of breast cancer have also been reported in younger women and the leading cause in them is their lifestyle pattern or they may be carriers of high penetrance mutated genes. Premenopausal women who have breast cancer have been diagnosed with aggressive build-up of tumors and are therefore at more risk of loss of life. Mammography is an effective way to test for breast cancer in women after menopause but is not so effective for premenopausal women or younger females. Imaging techniques like contrast-enhanced MRI can up to some extent indicate the presence of a tumor but it cannot adequately differentiate between benign and malignant tumors. Although the 'omics' strategies continuing for the last 20 years have been helpful at the molecular level in enabling the characteristics and proper understanding of such tumors over long-term longitudinal monitoring. Classification, diagnosis, and prediction of the outcomes have been made through tissue and serum biomarkers but these also fail to diagnose the disease at an early stage. Considerably there is no adequate detection technique present globally that can help early detection and provide adequate specificity, safety, sensitivity, and convenience for the younger and premenopausal women, thereby it becomes necessary to take early measures and build efficient tools and techniques for the same. Through biopsies of nipple aspirate fluid (NAF) biomarker profiling can be performed. It is a naturally secreted fluid from the cells of epithelium found in the breast. Nowadays, home-based liquid biopsy collection kits are also available through which a routine check on breast health can be performed with the help of NAF. Herein, we will review the biomarker screening liquid biopsy, and the new emerging technologies for the examination of cancer at an early stage, especially in premenopausal women.

The Diagnostic Value of microRNA Expression Analysis in Detecting Intraductal Papillomas in Patients with Pathological Nipple Discharge

Patients with pathological nipple discharge (PND) often undergo local surgical procedures because standard radiologic imaging fails to identify the underlying cause. MicroRNA (MiRNA) expression analysis of nipple fluid holds potential for distinguishing between breast diseases. This study aimed to compare miRNA expression levels between nipple fluids from patients with PND to identify possible relevant miRNAs that could differentiate between intraductal papillomas and no abnormalities in the breast tissue. Nipple fluid samples from patients with PND without radiological and pathological suspicion for malignancy who underwent a ductoscopy procedure were analyzed. We used univariate and multivariate regression analyses to identify nipple fluid miRNAs differing between pathologically confirmed papillomas and breast tissue without abnormalities. A total of 27 nipple fluid samples from patients with PND were included for miRNA expression analysis. Out of the 22 miRNAs examined, only miR-145-5p was significantly differentially expressed (upregulated) in nipple fluid from patients with an intraductal papilloma compared to patients showing no breast abnormalities (OR 4.76, p = 0.046), with a diagnostic accuracy of 92%. miR-145-5p expression in nipple fluid differs for intraductal papillomas and breast tissue without abnormalities and, therefore, has potential as a diagnostic marker to signal presence of papillomas in PND patients. However, further refinement and validation in clinical trials are necessary to establish its clinical applicability.

The role of the oxytocin system in the resilience of patients with breast cancer

Breast cancer is a grave traumatic experience that can profoundly compromise patients' psychological resilience, impacting their overall quality of life. The oxytocin system represents one of the essential neurobiological bases of psychological resilience and plays a critical role in regulating resilience in response to social or traumatic events during adulthood. Oxytocin, through its direct interaction with peripheral or central oxytocin receptors, has been found to have a significant impact on regulating social behavior. However, the precise mechanism by which the activation of peripheral oxytocin receptors leads to improved social is still not completely comprehended and requires additional research. Its activation can modulate psychological resilience by influencing estrogen and its receptors, the hypothalamic-pituitary-adrenal axis, thyroid function, 5-hydroxytryptamine metabolism levels, and arginine pressure release in breast cancer patients. Various interventions, including psychotherapy and behavioral measures, have been employed to improve the psychological resilience of breast cancer patients. The potential effectiveness of such interventions may be underpinned by their ability to modulate oxytocin release levels. This review provides an overview of the oxytocin system and resilience in breast cancer patients and identifies possible future research directions and interventions.

Localized Drug Delivery Systems: An Update on Treatment Options for Head and Neck Squamous Cell Carcinomas

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers in the world, with surgery, radiotherapy, chemotherapy, and immunotherapy being the primary treatment modalities. The treatment for HNSCC has evolved over time, due to which the prognosis has improved drastically. Despite the varied treatment options, major challenges persist. HNSCC chemotherapeutic and immunotherapeutic drugs are usually administered systemically, which could affect the patient's quality of life due to the associated side effects. Moreover, the systemic administration of salivary stimulating agents for the treatment of radiation-induced xerostomia is associated with toxicities. Localized drug delivery systems (LDDS) are gaining importance, as they have the potential to provide non-invasive, patient-friendly alternatives to cancer therapy with reduced dose-limiting toxicities. LDDSs involve directly delivering a drug to the tissue or organ affected by the disease. Some of the common localized routes of administration include the transdermal and transmucosal drug delivery system (DDSs). This review will attempt to explore the different treatment options using LDDSs for the treatment of HNSCC and radiotherapy-induced damage and their potential to provide a better experience for patients, as well as the obstacles that need to be addressed to render them successful.

Biomarker Reproducibility Challenge: A Review of Non-Nucleotide Biomarker Discovery Protocols from Body Fluids in Breast Cancer Diagnosis

Breast cancer has now become the most commonly diagnosed cancer, accounting for one in eight cancer diagnoses worldwide. Non-invasive diagnostic biomarkers and associated tests are superlative candidates to complement or improve current approaches for screening, early diagnosis, or prognosis of breast cancer. Biomarkers detected from body fluids such as blood (serum/plasma), urine, saliva, nipple aspiration fluid, and tears can detect breast cancer at its early stages in a minimally invasive way. The advancements in high-throughput molecular profiling (omics) technologies have opened an unprecedented opportunity for unbiased biomarker detection. However, the irreproducibility of biomarkers and discrepancies of reported markers have remained a major roadblock to clinical implementation, demanding the investigation of contributing factors and the development of standardised biomarker discovery pipelines. A typical biomarker discovery workflow includes pre-analytical, analytical, and post-analytical phases, from sample collection to model development. Variations introduced during these steps impact the data quality and the reproducibility of the findings. Here, we present a comprehensive review of methodological variations in biomarker discovery studies in breast cancer, with a focus on non-nucleotide biomarkers (i.e., proteins, lipids, and metabolites), highlighting the pre-analytical to post-analytical variables, which may affect the accurate identification of biomarkers from body fluids.

Elevated miR-29c-5p Expression in Nipple Aspirate Fluid Is Associated with Extremely High Mammographic Breast Density

Simple Summary

High mammographic density is a known risk factor for breast cancer. However, the underlying mechanisms of high mammographic density development and breast cancer are unknown. MicroRNAs are potential biomarkers indicative of carcinogenesis and can be assessed in nipple aspirate fluid. We used nipple aspirate fluid from women with very low and extremely high mammographic density to examine differences in expression of multiple miRNAs between both extremes in the spectrum of mammographic density. We found that hsa-miR-29c-5p was upregulated in an extremely high mammographic density context and potential targets were identified that might provide clues of the relationship between high mammographic density and breast cancer risk. Understanding the relationship between high mammographic density and breast cancer is of great value for early breast cancer diagnosis and treatment. With our research we provide new insight into this relationship and further research could determine the effects of dysregulated hsa-miR-29c-5p on the identified candidate targets.

Abstract

High mammographic density (MD) is associated with an increased risk of breast cancer, however the underlying mechanisms are largely unknown. This research aimed to identify microRNAs (miRNAs) that play a role in the development of extremely dense breast tissue. In the discovery phase, 754 human mature miRNAs were profiled in 21 extremely high MD- and 20 very low MD-derived nipple aspirate fluid (NAF) samples from healthy women. In the validation phase, candidate miRNAs were assessed in a cohort of 89 extremely high MD and 81 very low MD NAF samples from healthy women. Independent predictors of either extremely high MD or miRNA expression were identified by logistic regression and linear regression analysis, respectively. mRNA targets and pathways were identified through miRTarBase, TargetScan, and PANTHER pathway analysis. Statistical analysis identified four differentially expressed miRNAs during the discovery phase. During the validation, linear regression (p = 0.029; fold change = 2.10) and logistic regression (p = 0.048; odds ratio = 1.38) showed that hsa-miR-29c-5p was upregulated in extremely high MD-derived NAF. Identified candidate mRNA targets of hsa-miR-29c-5p are CFLAR, DNMT3A, and PTEN. Further validation and exploration of targets and downstream pathways of has-miR-29c-5p will provide better insight into the processes involved in the development of high MD and in the associated increased risk of breast cancer.

Patient-centered research: how do women tolerate nipple fluid aspiration as a potential screening tool for breast cancer?

Background

Nipple fluid aspiration (NFA) is a technique to acquire nipple aspirate fluid (NAF), which is considered a rich source of breast-specific biomarkers. Originating directly from the mammary ducts, this liquid biopsy can offer insight into the process of carcinogenesis at its earliest stage and therefore could be of added value to the current imaging-based breast cancer screening tools. With that in mind, it is necessary to know how well NFA is tolerated.

Aim

To evaluate the participants’ tolerability of NFA compared to breast imaging screening methods and blood draws.

Materials and methods

Three cohorts of women underwent NFA: healthy women (n = 190), women diagnosed with breast cancer (n = 137) and women at high risk of developing breast cancer (n = 48). A 0–10 discomfort score of NFA, mammography, breast MRI and blood draws, was filled in at the study visits, which took place once or annually.

Results

The median discomfort rate of NFA was 1, which was significantly lower than the median discomfort of mammography and breast MRI (5 and 3, respectively, p < 0.001), but significantly higher than median discomfort for blood draws (0, p < 0.001). The great majority of women would undergo the procedure again (98%) and recommend it to others (97%).

Conclusion

This study shows that NFA was well tolerated by healthy women, women diagnosed with breast cancer and high-risk women. This makes NFA a feasible method to pursue as a potential future breast cancer early detection tool, based on resident biomarkers.

Trial registration

NL41845.041.12, NL57343.041.16 and NL11690.041.06 in trialregister.nl.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09795-8.

Nipple aspirate fluid and its use for the early detection of breast cancer

Nipple aspirate fluid is the physiological biofluid lining ductal epithelial cells. Historically, cytology of nipple fluid has been the gold standard diagnostic method for assessment of ductal fluid in patients with symptomatic nipple discharge. The role of biomarker discovery in nipple aspirate fluid for assessment of asymptomatic and high-risk patients is highly attractive but evaluation to date is limited by poor diagnostic accuracy. However, the emergence of new technologies capable of identifying metabolites that have been previously thought unidentifiable within such small volumes of fluid, has enabled testing of nipple biofluid to be re-examined. This review evaluates the use of new technologies to evaluate the components of nipple fluid and their potential to serve as biomarkers in screening.

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 changing microRNA landscape by color and cloudiness: a cautionary tale for nipple aspirate fluid biomarker analysis

PURPOSE

Investigation of nipple aspirate fluid (NAF)-based microRNAs (miRNAs) as a potential screening tool for women at increased risk of developing breast cancer is the scope of our research. While aiming to identify discriminating NAF-miRNAs between women with different mammographic densities, we were confronted with an unexpected confounder: NAF sample appearance. Here we report and alert for the impact of NAF color and cloudiness on miRNA assessment.

METHODS

Seven classes of NAF colors coupled with cloudiness appearance were established. Using 173 NAF samples from 154 healthy women (19 samples were bilaterally collected), the expression of 14 target and 2 candidate endogenous control (EC) miRNAs was investigated using Taqman Advanced miRNA assays to identify significant differential expression patterns between color-cloudiness classes. Inter- and intra-individual variation of miRNA expression was analyzed using the coefficient of variation (CV).

RESULTS

We found that between the seven NAF classes, fold change miRNA expression differences ranged between 2.4 and 19.6 depending on the interrogated miRNA. Clear NAF samples exhibited higher miRNA expression levels compared to cloudy NAF samples with fold change differences ranging between 1.1 and 6.2. Inter-individual and intra-individual miRNA expression was fairly stable (CV < 15 %), but nevertheless impacted by NAF sample appearance. Within NAF classes, inter-individual variation was largest for green samples (CV 6-15 %) and smallest for bloody samples (CV 2-6 %).

CONCLUSIONS

Our data indicate that NAF color and cloudiness influence miRNA expression and should, therefore, be systematically registered using an objective color classification system. Given that sample appearance is an inherent feature of NAF, these variables should be statistically controlled for in multivariate data analyses. This cautionary note and recommendations could be of value beyond the field of NAF-miRNAs, given that variability in sample color and cloudiness is likewise observed in liquid biopsies such as urine, cerebrospinal fluid and sputum, and could thereby influence the levels of miRNAs and other biomarkers.

High-Throughput Proteomic Profiling of Nipple Aspirate Fluid from Breast Cancer Patients Compared with Non-Cancer Controls: A Step Closer to Clinical Feasibility

BACKGROUND

Early detection of breast cancer (BC) is critical for increasing survival rates. However, current imaging approaches can provide ambiguous results, requiring invasive tissue biopsy for a definitive diagnosis. Multi-dimensional mass spectrometric analysis has highlighted the invaluable potential of nipple aspirate fluid (NAF) as a non-invasive source of early detection biomarkers, by identifying a multitude of proteins representative of the changing breast microenvironment. However, technical challenges with biomarker validation in large cohorts remain due to low sample throughput, impeding progress towards clinical utility. Rather, by employing a high-throughput method, that is more practicable for clinical utility, perturbations of the most abundant NAF proteins in BC patients compared with non-cancer (NC) controls could be monitored and validated in larger groups.

METHOD

We characterized matched NAF pairs from BC (n = 9) and NC (n = 4) volunteers, using a rapid one dimensional liquid chromatography-mass spectrometry (1D LC-MS/MS) approach.

RESULTS

Overall, 198 proteins were relatively quantified, of which 40 were significantly differentiated in BC samples, compared with NC (p ≤ 0.05), with 26 upregulated and 14 downregulated. An imbalance in immune response and proteins regulating cell growth, maintenance and communication were identified.

CONCLUSIONS

Our findings show 1D LC-MS/MS can quantify changes reflected in the NAF proteome associated with breast cancer development.

Breast health screening: a UK-wide questionnaire

Background

Currently, there is an unmet clinical need in identifying and screening women at high risk of breast cancer, where tumours are often aggressive and treatment intervention is too late to prevent metastasis, recurrence and mortality. This has been brought into sharp focus by the SARS-CoV-2 global pandemic, constantly changing hospital policies and surgical guidelines in reducing access to established screening and treatment regimens. Nipple aspirate fluid (NAF), is thought to provide a unique window into the biological processes occurring within the breast, particularly in the context of a developing neoplasm. Evaluation of NAF in asymptomatic women, for novel chemical biomarkers of either early disease and/or cancer risk offers tremendous promise as a tool to facilitate early detection and to supplement screening. However, it is acceptability as a method of collection and screening by women is critical and yet unknown. A breast health questionnaire was disseminated to women through breast cancer charities, patient support groups and social media platforms, with the aim of collecting opinions on the acceptability of use of NAF as a potential screening tool.

Method

Following ethical approval a questionnaire was prepared using online surveys consisting of four parts: (a) introduction on breast health screening in the UK, (b) core demographic data, (c) questions regarding screening and the acceptability of using NAF and (d) opinions about the process of collecting and using nipple fluid for screening. The voluntary and anonymous questionnaire was disseminated through social media, professional networks, charity websites and by individuals between October 2019 and December 2020. Survey responses were collected electronically, and the data analysed using online surveys statistical tools.

Results

A total of 3178 women completed the questionnaire (65.9% Caucasian, 27.7% Asian/British Asian, 0.6% black and 5.0% other). Of these, 2650 women (83.4%) had no prior knowledge of NAF and 89.4% were unaware that NAF can be expressed in up to 90% of all women. Concerning their risk of breast cancer, 89.8% of women were keen to know their future risk of breast cancer, 8.5% were unsure whether they wanted to know their risk and a further, 1.6% did not want to know. Regarding screening, 944 women (29.8%) were unaware of the lack of routine National Health Service Breast Screening for those under the age of 47 years. Furthermore, 53.0% of women were unaware that mammographic screening is affected by breast density. In terms of the acceptability of home testing for breast health, 92.0% were keen to undergo a home test. Both 79.7% and 70.9% stated they would consider hand massage and a breast pump to acquire nipple fluid samples, respectively. A further 48.6% of women would consider the use of a hormonal nasal spray for the same purpose. However, with regards to acquiring results from NAF testing, 42.6% of women would prefer to receive results at home and 34.2% in a medical facility. Finally, 91.6% of women believed that breast health should be incorporated as part of school education curriculum.

Conclusion

Public awareness regarding breast screening protocols and limitations of mammography could be improved. Many women were unaware that NAF might be a useful biofluid for future risk prediction, and yet the concept of self-testing of nipple fluid, with either hand massage or a breast pump was well received. Efforts should be made to increase awareness of the benefits of alternative and supplementary tests, especially in the context of high-risk individuals and younger patients.

Lessons Learned from Setting Up a Prospective, Longitudinal, Multicenter Study with Women at High Risk for Breast Cancer

Women identified with an increased risk of breast cancer due to mutations in cancer susceptibility genes or a familial history of breast cancer undergo tailored screening with the goal of detecting tumors earlier, when potential curative interventions are still possible. Ideally, screening would identify signs of carcinogenesis even before a tumor is detectable by imaging. This could be achieved by timely signaling of altered biomarker levels for precancerous processes in liquid biopsies. Currently, the Nipple Aspirate Fluid (NAF) and the Trial Early Serum Test BREAST cancer (TESTBREAST), both ongoing, prospective, multicenter studies, are investigating biomarkers in liquid biopsies to improve breast cancer screening in high-risk women. The NAF study focuses on changes over time in miRNA expression levels both in blood and NAF samples, whereas the TESTBREAST study analyzes changes in protein levels in blood samples at sequential interval timepoints. These within-subject changes are studied in relation to later occurrence of breast cancer using a nested case-control design. These longitudinal studies face their own challenges in execution, such as hindrances in logistics and in sample processing that were difficult to anticipate. This article offers insight into those challenges and concurrently aims to provide useful strategies for the set-up of similar studies.See related commentary by Sauter, p. 429.

The Physiological MicroRNA Landscape in Nipple Aspirate Fluid: Differences and Similarities with Breast Tissue, Breast Milk, Plasma and Serum

Background: MicroRNAs (miRNAs) target 60% of human messenger RNAs and can be detected in tissues and biofluids without loss of stability during sample processing, making them highly appraised upcoming biomarkers for evaluation of disease. However, reporting of the abundantly expressed miRNAs in healthy samples is often surpassed. Here, we characterized for the first time the physiological miRNA landscape in a biofluid of the healthy breast: nipple aspirate fluid (NAF), and compared NAF miRNA expression patterns with publically available miRNA expression profiles of healthy breast tissue, breast milk, plasma and serum. Methods: MiRNA RT-qPCR profiling of NAF (n = 41) and serum (n = 23) samples from two healthy female cohorts was performed using the TaqMan OpenArray Human Advanced MicroRNA 754-Panel. MiRNA quantification data based on non-targeted or multi-targeted profiling techniques for breast tissue, breast milk, plasma and serum were retrieved from the literature by means of a systematic search. MiRNAs from each individual study were orderly ranked between 1 and 50, combined into an overall ranking per sample type and compared. Results: NAF expressed 11 unique miRNAs and shared 21/50 miRNAs with breast tissue. Seven miRNAs were shared between the five sample types. Overlap between sample types varied between 42% and 62%. Highly ranked NAF miRNAs have established roles in breast carcinogenesis. Conclusion: This is the first study to characterize and compare the unique physiological NAF-derived miRNA landscape with the physiological expression pattern in breast tissue, breast milk, plasma and serum. Breast-specific sources did not mutually overlap more than with systemic sources. Given their established role in carcinogenesis, NAF miRNA assessment could be a valuable tool in breast tumor diagnostics.

Application of Nipple Aspirate Fluid miRNA Profiles for Early Breast Cancer Detection and Management

The authors of the recently published review, "Why the Gold Standard Approach by Mammography Demands Extension by Multiomics [...].

Evaluation of nipple aspirate fluid as a diagnostic tool for early detection of breast cancer

There has been tremendous progress in detection of breast cancer in postmenopausal women, resulting in two-thirds of women surviving more than 20 years after treatment. However, breast cancer remains the leading cause of cancer-related deaths in premenopausal women. Breast cancer is increasing in younger women due to changes in life-style as well as those at high risk as carriers of mutations in high-penetrance genes. Premenopausal women with breast cancer are more likely to be diagnosed with aggressive tumours and therefore have a lower survival rate. Mammography plays an important role in detecting breast cancer in postmenopausal women, but is considerably less sensitive in younger women. Imaging techniques, such as contrast-enhanced MRI improve sensitivity, but as with all imaging approaches, cannot differentiate between benign and malignant growths. Hence, current well-established detection methods are falling short of providing adequate safety, convenience, sensitivity and specificity for premenopausal women on a global level, necessitating the exploration of new methods. In order to detect and prevent the disease in high risk women as early as possible, methods that require more frequent monitoring need to be developed. The emergence of "omics" strategies over the last 20 years, enabling the characterisation and understanding of breast cancer at the molecular level, are providing the potential for long term, longitudinal monitoring of the disease. Tissue and serum biomarkers for breast cancer stratification, diagnosis and predictive outcome have emerged, but have not successfully translated into clinical screening for early detection of the disease. The use of breast-specific liquid biopsies, such as nipple aspirate fluid (NAF), a natural secretion produced by breast epithelial cells, can be collected non-invasively for biomarker profiling. As we move towards an age of active surveillance, home-based liquid biopsy collection kits are increasingly being applied and these could provide a paradigm shift where NAF biomarker profiling is used for routine breast health monitoring. The current status of established and newly emerging imaging techniques for early detection of breast cancer and the potential for alternative biomarker screening of liquid biopsies, particularly those applied to high-risk, premenopausal women, will be reviewed.

DNA promoter hypermethylation in nipple fluid: a potential tool for early breast cancer detection

Introduction

Nipple fluid aspiration provides direct non-invasive sampling of fluid from the mammary ductal system, where the majority of breast cancers originate. DNA promoter hypermethylation (“methylation”) occurs early and at high frequency in breast carcinogenesis, bearing the potential as a biomarker for cancer detection at its earliest stages. We assessed methylation in nipple fluid from breasts of healthy women, of women with sporadic breast cancer and of their contralateral breasts. Our goal was to investigate whether nipple fluid can be used as a reliable methylation biomarker source.

Methods

Methylation levels of 13 genes were analysed by quantitative multiplex-methylation specific PCR (QM-MSP) in nipple fluid samples from breasts of healthy women, and from the affected and contralateral breasts of breast cancer patients.

Results

Methylation analysis of the low-volume nipple fluid samples was feasible. Despite the generally low methylation levels, cancerous and healthy breasts nipple fluid could be discriminated with an area under the receiver operating characteristic curve (AUC) of 0.64 (p<0.01) based on a multivariate model including AKR1B1, ALX1, RASSF1A and TM6SF1. Within-patient differences between cancerous and contralateral nipple fluid samples were less prominent.

Conclusions

Cancerous nipple fluid contains increased levels of methylation of tumor suppressor genes that potentially could serve as a biomarker for early breast cancer detection.

Nipple aspirate fluid-A liquid biopsy for diagnosing breast health

Purpose

Nipple secretions are protein‐rich and a potential source of breast cancer biomarkers for breast cancer screening. Previous studies of specific proteins have shown limited correlation with clinicopathological features. Our aim, in this pilot study, was to investigate the intra‐ and interpatient protein composition of nipple secretions and the implications for their use as liquid biopsies.

Experimental design

Matched pairs of nipple discharge/nipple aspirate fluid (NAF, n = 15) were characterized for physicochemical properties and SDS‐PAGE. Four pairs were selected for semiquantitative proteomic profiling and trypsin‐digested peptides analyzed using 2D‐LC Orbitrap Fusion MS. The resulting data were subject to bioinformatics analysis and statistical evaluation for functional significance.

Results

A total of 1990 unique proteins were identified many of which are established cancer‐associated markers. Matched pairs shared the greatest similarity (average Pearson correlation coefficient of 0.94), but significant variations between individuals were observed.

Conclusions and clinical relevance

This was the most complete proteomic study of nipple discharge/nipple aspirate fluid to date providing a valuable source for biomarker discovery. The high level of milk proteins in healthy volunteer samples compared to the cancer patients was associated with galactorrhoea. Using matched pairs increased confidence in patient‐specific protein levels but changes relating to cancer stage require investigation of a larger cohort.

Genetic Determinants of Nipple Aspiration Fluid Yield

PURPOSE

Nipple aspiration fluid (NAF) is a non-invasively-acquired biosample that can provide a window into the breast environment, but NAF yield is highly variable. Its determinants must be better understood for studies of breast cancer risk. The wet earwax phenotype was identified as one determinant of NAF yield in the 1970s, and is linked to single nucleotide polymorphisms (SNPs) in the ATP-binding cassette transporter gene ABCC11. We have investigated this, as well as SNPs in the prolactin (PRL) and prolactin receptor (PRLR) genes, in relation to NAF yield.

METHODS

DNA was extracted from white blood cells of 557 NAF yielders and 359 non-yielders, and was used to genotype ABCC11 (rs17822931), PRL (rs849870, rs849872, rs849886, rs2244502, rs1341239), and PRLR (rs37364, rs34024951, rs1610218, rs9292575, rs7718468) using Taqman genotyping assay. The association between NAF yield and each single SNP was analyzed using logistic regression adjusting for age, race, and menopausal status.

RESULTS

ABCC11 rs17822931 showed a negative association with NAF yield [odds ratio (OR) 0.66, 95 % confidence interval (CI) 0.49-0.88; p = 0.004]. The PRL rs849870 and the haplotype combination with other SNPs showed a marginal association with NAF yield. In addition, the years since last birth also showed negative association with NAF yielding (OR 0.98, 95 % CI 0.96-0.99; p = 0.001). The combination of the years since last birth with ABCC11 SNP revealed significant interaction between reproductive factor and genetic factor.

CONCLUSIONS

Our results confirmed the association between NAF yield and earwax phenotype through ABCC11 genotype. Combined with the recency of last birth, ABCC11 genotype should be considered in the design of studies utilizing NAF as a biosample.

Repeated nipple fluid aspiration: compliance and feasibility results from a prospective multicenter study

BACKGROUND

Despite intensive surveillance, a high rate of interval malignancies is still seen in women at increased breast cancer risk. Therefore, novel screening modalities aiming at early detection remain needed. The intraductal approach offers the possibility to directly sample fluid containing cells, DNA and proteins from the mammary ductal system where, in the majority of cases, breast cancer originates. Fluid from the breast can non-invasively be obtained by oxytocin-assisted vacuum aspiration, called nipple fluid aspiration (NFA). The goal of this feasibility study was to evaluate the potential of repeated NFA, which is a critical and essential step to evaluate its possible value as a breast cancer screening method.

METHODS

In this multicenter, prospective study, we annually collected nipple fluid for up to 5 consecutive years from women at increased breast cancer risk, and performed a questionnaire-based survey regarding discomfort of the aspiration. Endpoints of the current interim analyses were the feasibility and results of 994 NFA procedures in 451 women with total follow-up of 560 person years of observation.

RESULTS

In this large group of women at increased risk of breast cancer, repetitive NFA appeared to be feasible and safe. In 66.4% of aspirated breasts, nipple fluid was successfully obtained. Independent predictive factors for successful NFA were premenopausal status, spontaneous nipple discharge, smaller breast size, bilateral oophorectomy and previous use of hormone replacement therapy or anti-hormonal treatment. The procedure was well tolerated with low discomfort. Drop-out rate was 20%, which was mainly due to repeated unsuccessful aspiration attempts. Only 1.6% of women prematurely declined further participation because of side effects.

CONCLUSIONS

Repeated NFA in women at increased breast cancer risk is feasible and safe. Therefore, NFA is a promising method to non-invasively obtain a valuable source of potential breast cancer specific biomarkers.

The cancer secretome, current status and opportunities in the lung, breast and colorectal cancer context

Despite major improvements on the knowledge and clinical management, cancer is still a deadly disease. Novel biomarkers for better cancer detection, diagnosis and treatment prediction are urgently needed. Proteins secreted, shed or leaking from the cancer cell, collectively termed the cancer secretome, are promising biomarkers since they might be detectable in blood or other biofluids. Furthermore, the cancer secretome in part represents the tumor microenvironment that plays a key role in tumor promoting processes such as angiogenesis and invasion. The cancer secretome, sampled as conditioned medium from cell lines, tumor/tissue interstitial fluid or tumor proximal body fluids, can be studied comprehensively by nanoLC-MS/MS-based approaches. Here, we outline the importance of current cancer secretome research and describe the mass spectrometry-based analysis of the secretome. Further, we provide an overview of cancer secretome research with a focus on the three most common cancer types: lung, breast and colorectal cancer. We conclude that the cancer secretome research field is a young, but rapidly evolving research field. Up to now, the focus has mainly been on the discovery of novel promising secreted cancer biomarker proteins. An interesting finding that merits attention is that in cancer unconventional secretion, e.g. via vesicles, seems increased. Refinement of current approaches and methods and progress in clinical validation of the current findings are vital in order to move towards applications in cancer management. This article is part of a Special Issue entitled: An Updated Secretome.

Improving early breast cancer detection: focus on methylation

The need for additional breast cancer screening tools is indisputably high, as one may conclude from the high rate of interval malignancies in women undergoing regular screening. DNA promoter methylation frequently occurs during breast carcinogenesis and is an early event in this process. Moreover, a field defect for methylation has been described and methylation values can reliably be assessed in limited amounts of DNA. Simultaneous detection of methylation of a panel of genes in breast fluids and/or blood derivatives could be both sufficiently specific and sensitive to be of additive value to current imaging-based screening methods. This review describes the recent developments in methylation detection in breast fluids, serum and plasma that paved the way for large prospective studies. These studies will provide us with the definite answer as to what will be the additive value of defining the methylation status of specific genes to current imaging-based screening methods.