Epithelial cells in nipple aspirate fluid and subsequent breast cancer risk: a historic prospective study

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.

Diagnostic Accuracy of Nipple Aspirate Fluid Cytology in Asymptomatic Patients: A Meta-analysis and Systematic Review of the Literature

PURPOSE

To calculate the diagnostic accuracy of nipple aspirate fluid (NAF) cytology.

BACKGROUND

Evaluation of NAF cytology in asymptomatic patients conceptually offers a non-invasive method for either screening for breast cancer or else predicting or stratifying future cancer risk.

METHODS

Studies were identified by performing electronic searches up to August 2019. A meta-analysis was conducted to attain an overall pooled sensitivity and specificity of NAF for breast cancer detection.

RESULTS

A search through 938 studies yielded a total of 19 studies. Overall, 9308 patients were examined, with cytology results from 10,147 breasts [age (years), mean ± SD = 49.73 ± 4.09 years]. Diagnostic accuracy meta-analysis of NAF revealed a pooled specificity of 0.97 (95% CI 0.97-0.98), and sensitivity of 0.64 (95% CI 0.62-0.66).

CONCLUSIONS

The diagnostic accuracy of nipple smear cytology is limited by poor sensitivity. If nipple fluid assessment is to be used for diagnosis, then emerging technologies for fluid biomarker analysis must supersede the current diagnostic accuracy of NAF cytology.

Examination of Duct Physiology in the Human Mammary Gland

Background

The human breast comprise several ductal systems, or lobes, which contain a small amount of fluid containing cells, hormones, proteins and metabolites. The complex physiology of these ducts is likely a contributing factor to the development of breast cancer, especially given that the vast majority of breast cancers begin in a single lobular unit.

Methods

We examined the levels of total protein, progesterone, estradiol, estrone sulfate, dehydroepiandrosterone sulfate, and macrophages in ductal fluid samples obtained from 3 ducts each in 78 women, sampled twice over a 6 month period. Samples were processed for both cytological and molecular analysis. Intraclass correlation coefficients and mixed models were utilized to identify significant data.

Results

We found that the levels of these ductal fluid components were generally uncorrelated among ducts within a single breast and over time, suggesting that each lobe within the breast has a distinct physiology. However, we also found that estradiol was more correlated in women who were nulliparous or produced nipple aspirate fluid.

Conclusions

Our results provide evidence that the microenvironment of any given lobular unit is unique to that individual unit, findings that may provide clues about the initiation and development of ductal carcinomas.

An Improved Breast Epithelial Sampling Method for Molecular Profiling and Biomarker Analysis in Women at Risk for Breast Cancer

BACKGROUND

There is a strong need to define the molecular changes in normal at-risk breast epithelium to identify biomarkers and new targets for breast cancer prevention and to develop a molecular signature for risk assessment. Improved methods of breast epithelial sampling are needed to promote whole-genome molecular profiling, increase ductal epithelial cell yield, and reduce sample cell heterogeneity.

METHODS

We developed an improved method of breast ductal sampling with ductal lavage through a 22-gauge catheter and collection of ductal samples with a microaspirator. Women at normal risk or increased risk for breast cancer were studied. Ductal epithelial samples were analyzed for cytopathologic changes, cellular yield, epithelial cell purity, quality and quantity of DNA and RNA, and use in multiple downstream molecular applications.

RESULTS

We studied 50 subjects, including 40 subjects at normal risk for breast cancer and 37 subjects with non-nipple aspirate fluid-yielding ducts. This method provided multiple 1.0 mL samples of high ductal epithelial cell content (median ≥8 samples per subject of ≥5,000 cells per sample) with 80%-100% epithelial cell purity. Extraction of a single intact ductal sample (fluid and cells) or the separate frozen cellular component provided DNA and RNA for multiple downstream studies, including quantitative reverse transcription- polymerase chain reaction (PCR) for microRNA, quantitative PCR for the human telomerase reverse transcriptase gene, whole-genome DNA amplification, and array comparative genomic hybridization analysis.

CONCLUSION

An improved breast epithelial sampling method has been developed, which should significantly expand the acquisition and biomarker analysis of breast ductal epithelium in women at risk for breast cancer.

Proliferative epithelial disease identified in nipple aspirate fluid and risk of developing breast cancer: a systematic review

BACKGROUND

Guideline panels recognize the need to increase the accuracy of identifying women at high risk of developing breast cancer who would benefit from prevention strategies. The characterization of proliferative epithelial disease found in nipple aspirate fluid (PED-NAF) may be a relevant risk factor.

OBJECTIVE

To comprehensively review the published literature to characterize and summarize abnormal cytology detected by NAF and the association of PED-NAF with subsequent risk of developing breast cancer.

RESEARCH DESIGN AND METHODS

Literature identified by systematic searches in MEDLINE PubMed and the Cochrane Library was screened for articles containing primary data on NAF cytology based on predefined inclusion and exclusion criteria.

MAIN OUTCOME MEASURES

Study characteristics, cytological group distribution, and incidence of breast cancer.

RESULTS

Thirty articles were included after full-text review, of which 16 were analyzed, containing data on 20,808 unique aspirations from over 17,378 subjects. Seven (44%) of the studies used the King cytological classification system. Among aspirations from women free of breast cancer, 51.5% contained fluid, in which over 27.7% had PED on cytology. In the two prospective studies of 7850 cancer-free women, abnormal cytology by NAF carried a 2.1-fold higher risk (95% CI, 1.6-2.6; p < 0.001) of developing breast cancer, compared with women from whom no fluid could be obtained.

CONCLUSIONS

PED-NAF among women free of breast cancer, compared with no fluid being obtained, has an independent risk of developing breast cancer comparable to the risk of a woman with a positive family history of breast cancer. These findings have implications for augmenting risk prediction and clinical decisions concerning breast cancer surveillance and chemoprevention. As with all reviews, heterogeneity across studies may have influenced the results. The limited literature calls for prospective studies on asymptomatic women with long-term follow-up.

Cytology in nipple aspirate fluid during a randomized soy food intervention among premenopausal women

Because soy food consumption may influence breast tissue activity, we examined its effect on the presence of epithelial cells in nipple aspirate fluid (NAF). In a randomized, crossover design, 82 premenopausal women completed a high-soy and a low-soy diet for 6 mo each, separated by a 1-mo washout period. They provided NAF samples at baseline, 6 mo, and 13 mo during the midluteal phase of the menstrual cycle. Papanicolaou-stained cytology slides (for 33 women at baseline, 24 at low-soy, and 36 at high-soy) were evaluated in women with sufficient NAF. Mixed models evaluated the effect of the high-soy diet on epithelial cytology as compared to baseline and the low-soy diet. At the end of the high-soy diet, cytological subclass had decreased in 8 (24%) and increased in 3 (9%) women as compared to baseline, whereas the respective values were 3 (14%) and 6 (29%) for the low-soy diet samples (P = 0.32). Only the change in subclass indicated a trend in lower cytological class (P = 0.06). Contrary to an earlier report, the number of NAF samples with hyperplastic epithelial cells did not increase after a soy intervention in amounts consumed by Asians.

Paired ductal carcinoma in situ and invasive breast cancer lesions in the D-loop of the mitochondrial genome indicate a cancerization field effect

Alterations in the mitochondrial genome have been chronicled in most solid tumors, including breast cancer. The intent of this paper is to compare and document somatic mitochondrial D-loop mutations in paired samples of ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC) indicating a potential breast ductal epithelial cancerization field effect. Paired samples of these histopathologies were laser-captured microdissected (LCM) from biopsy, lumpectomy, and mastectomy tissues. Blood samples were collected as germplasm control references. For each patient, hypervariable region 1 (HV1) in the D-loop portion of the mitochondrial genome (mtGenome) was sequenced for all 3 clinical samples. Specific parallel somatic heteroplasmic alterations between these histopathologies, particularly at sites 16189, 16223, 16224, 16270, and 16291, suggest the presence of an epithelial, mitochondrial cancerization field effect. These results indicate that further characterization of the mutational pathway of DCIS and IBC may help establish the invasive potential of DCIS. Moreover, this paper indicates that biofluids with low cellularity, such as nipple aspirate fluid and/or ductal lavage, warrant further investigation as early and minimally invasive detection mediums of a cancerization field effect within breast tissue.

Does ductal lavage assert its role as a noninvasive diagnostic modality to identify women at low risk of breast cancer development?

Objective

Ductal lavage (DL) involves evaluation of the ductal system of the breast for detection of intra-ductal carcinomas and precursor lesions by collecting breast epithelial cells using a small-gauge catheter inserted into a ductal orifice on the nipple. The aim of this survey was to analyze cytologic features of samples obtained from low-risk women with DL and to elucidate the efficacy of this diagnostic modality in evaluating fluid production, cannulating and determining atypical breast epithelial cells.

Methods

Into this prospective study were consecutively registered 80 women between ages 28 to 67. Nipple aspiration was performed to identify all fluid-yielding ducts. According to the grading of specific features the interpretation of the sample included: normal/benign (category, 0), mild atypical (category, I), markedly atypical (category, II) or malignant (category, III) disorders.

Results

Ninety five percent (316/334) of the nipple aspirate fluid samples were classified as category 0, 4.8% (16/334) as category I and 0.2% (2/334) as category II changes. Category III disorders were not detected. Therefore, in 80% of the women examined results were within normal limits while 17.5% of the participants presented mild atypical and 2.5% markedly atypical rates.

Conclusion

DL collection procedure proved to be rapid as well as acceptable by the women studied. It retains the advantage over other methods of nipple aspirate fluid in that it is easy to perform, thereby removing most clinician variability. It also helped low risk women to discriminate those with breast disorders that require additional investigation, further follow-up or administration of preventive medication.

The volume of nipple aspirate fluid is not affected by 6 months of treatment with soy foods in premenopausal women

Based on the hypothesis that soy food consumption may influence breast tissue activity, we examined its effect on the production of nipple aspirate fluid (NAF), a possible indicator of breast cancer risk. Of 310 premenopausal women screened, 112 (36%) produced at least 10 μL of NAF, the minimum for study participation. In a crossover design, we randomized 96 women to 2 groups who, in reverse order, consumed a high-soy diet with 2 soy servings/d (1 serving = 177 mL soy milk, 126 g tofu, or 23 g soy nuts) and a low-soy diet with <3 servings/wk of soy for 6 mo each separated by a 1-mo washout period. During each diet period, 3 NAF samples were obtained (baseline and 3 and 6 mo) using a FirstCyte Aspirator and 4 urine samples (baseline and 1, 3, and 6 mo) were analyzed for isoflavonoids by liquid chromatography tandem MS. Adherence to the study protocol according to 24-h dietary recalls and urinary isoflavonoid excretion was high. The drop-out rate was 15% (n = 14); 82 women completed the intervention. The 2 groups produced similar mean NAF volumes at baseline (P = 0.95) but differed in age and previous soy intake and in their response to the intervention (P = 0.03). In both groups, NAF volume decreased during the first 3 mo of the high-soy diet period and returned to baseline at 6 mo, but there was no effect of the high-soy diet on NAF volume (P = 0.50 for diet; P-interaction = 0.21 for diet with time). Contrary to an earlier report, soy foods in amounts consumed by Asians did not increase breast tissue activity as assessed by NAF volume.

Risk assessment, screening and prevention of breast cancer: A look at cost-effectiveness

Recent suggestions by the United States Preventive Task Force to change the longstanding guidelines for screening mammography have raised the issue of cost-effectiveness in regards to breast cancer detection. Given the enormous number of women who have had, or who will be diagnosed with breast cancer, it is essential to maintain the quality of care that has been achieved here in the United States while utilizing a cost-effective approach. The following review attempts a close examination of current methods available for risk assessment, screening and prevention programs. These programs must be carefully considered and analyzed prior to implementing cost-saving changes to current clinical standards that have proven successful in decreasing the mortality from breast cancer throughout the world.

Obesity is associated with atypia in breast ductal lavage of women with proliferative breast disease

BACKGROUND

Benign proliferative breast disease without atypia slightly increases breast cancer risk but there are currently few clinical options for breast cancer prevention in this group of women.

METHODS

We conducted a pilot study of women with a past diagnosis of proliferative breast disease with a goal to determine if the characteristics of cells obtained by breast ductal lavage were related to nutritional factors.

RESULTS

There were 57 women who enrolled. A total of 39 women yielded nipple aspirate fluid (NAF) samples and 36 underwent breast ductal lavage. Five of the lavage samples were acellular and 28 had at least 200 cells. Surprisingly, atypia was present in 11 women. Presence of atypia was associated with slight changes in morphometric features of the epithelial cells such as measures of circularity as obtained by image analysis, but the only variable significantly different in women with atypia (versus no atypia) was a higher mean body mass index. Body mass index was also significantly correlated with C-reactive protein (CRP) levels in the nipple aspirate fluid, indicating that obesity might have a pro-inflammatory effect on the breast that can contribute to increased rates of atypia.

CONCLUSIONS

Although the clinical significance of atypia in breast ductal lavage is uncertain, these results support further work on prevention of obesity as a strategy for reducing breast cancer risk.

Tolerability of breast ductal lavage in women from families at high genetic risk of breast cancer

BACKGROUND

Ductal lavage (DL) has been proposed as a minimally-invasive, well-tolerated tool for obtaining breast epithelial cells for cytological evaluation of breast cancer risk. We report DL tolerability in BRCA1/2 mutation-positive and -negative women from an IRB-approved research study.

METHODS

165 BRCA1/2 mutation-positive, 26 mutation-negative and 3 mutation unknown women underwent mammography, breast MRI and DL. Psychological well-being and perceptions of pain were obtained before and after DL, and compared with pain experienced during other screening procedures.

RESULTS

The average anticipated and experienced discomfort rating for DL, 47 and 48 (0-100), were significantly higher (p < 0.01) than the anticipated and experienced discomfort of mammogram (38 and 34), MRI (36 and 25) or nipple aspiration (42 and 27). Women with greater pre-existing emotional distress experienced more DL-related discomfort than they anticipated. Women reporting DL-related pain as worse than expected were nearly three times more likely to refuse subsequent DL than those reporting it as the same or better than expected. Twenty-five percent of participants refused repeat DL at first annual follow-up.

CONCLUSION

DL was anticipated to be and experienced as more uncomfortable than other procedures used in breast cancer screening. Higher underlying psychological distress was associated with decreased DL tolerability.

Does the new automated "HALO" nipple aspiration fluid system really deliver as promised? The answer is "No, but...": A literature review of the role of breast fluid cytology in cancer risk assessment

The HALO breast Pap test is a new automated nipple aspiration fluid (NAF) system that was recently introduced into the market. In an extensive marketing campaign directed principally toward OB/GYN practices, including endorsements from few local news media, HALO has been promoted as the "new Pap screening test for breast." Physicians are encouraged to perform this test on all women, as part of their annual examination, with claims that HALO will detect breast cancers as early as 10 years before mammography. These arguments are made more appealing to physician's offices by highlighting the potential positive financial impact on their practices, without consuming physician time, as medical assistants or technicians can perform this test. As a result of this directed campaign, cytology laboratories are increasingly confronted with implementing the HALO system and clinicians are increasingly soliciting pathologist's input regarding its validity. Yet, there is no data available regarding this new system, outside rare reports sponsored by the manufacturer. In this discussion, I examine the pros and cons of this new NAF system, including literature review of breast fluid cytology, and how it relates to breast cancer risk assessment.