Nutritional predictors for cellular nipple aspirate fluid: Nutrition and Breast Health 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.

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.

Influence of diet on nipple aspirate fluid production and estrogen levels

One possible mechanism how nutritional factors may affect breast cancer risk is through an influence on estrogen levels. Nipple aspirate fluid (NAF) is thought to provide a more direct insight into hormonal influences on breast tissue than serum. The ability to produce NAF may be an indicator of breast cancer risk. The current analysis was conducted as part of a soy trial in 92 premenopausal women and evaluated the relation of usual dietary intake with NAF volume and the most predominant steroidal estrogens in NAF and serum at baseline. Estradiol (E(2)) and estrone sulfate (E(1)S) were assessed in NAF and E(2), estrone (E(1)), and E(1)S, in serum using highly sensitive radioimmunoassays. The statistical analysis applied multivariate, log-linear regression models. Intake of saturated fat and cheese (p = 0.06 for both) indicated a positive trend with NAF volume whereas isoflavonoid and soy consumption suggested inverse associations (p = 0.01 and p = 0.08). For estrogens in NAF, total fat and monounsaturated fat intake was positively associated with E(2) (p = 0.05 and p = 0.02) and in serum, alcohol intake was associated with higher E(1)S levels (p = 0.02). These findings suggest a weak influence of dietary composition on NAF production and estrogen levels in serum and NAF.

Nutrients and nipple aspirate fluid composition: the breast microenvironment regulates protein expression and cancer aetiology

The aetiology of breast cancer is complex and multifactorial, and may include diet and xenobiotic compounds. A change in diet affects nutrient levels in blood, but to what extent diet can affect micronutrient concentrations in the breast is not yet well established. Breast nipple aspirate fluids (NAF) can be non-invasively obtained from the breast in most women; it represents a biological tool to assess metabolic changes in the breast ductal microenvironment. A wide variation in biomolecular and hormonal composition of NAFs collected from healthy and breast cancer patient may be due to genetic and nutritional factors; however, micro- and macro-nutrients may influence the secretory status of these women, thus NAF composition and risk of breast carcinoma. The aim of this overview is to highlight the detrimental/beneficial role that diet-related compounds in nipple aspirate fluid can have in breast cancer risk.

Effects of High Fruit-Vegetable and/or Low-Fat Intervention on Breast Nipple Aspirate Fluid Micronutrient Levels

BACKGROUND

A change in diet is known to affect micronutrient levels in blood but to what extent diet can affect micronutrient levels in the breast is not yet well established.

METHODS

Healthy, premenopausal women with a family history of breast cancer were randomized across four diet arms for 1 year in a 2 x 2 factorial design study: control, low-fat, high fruit-vegetable, and combination low-fat/high fruit-vegetable diets. Subjects were asked to collect breast nipple aspirate fluid (NAF) at 0, 6, and 12 months, and levels of micronutrients were measured in the fluid.

RESULTS

A total of 122 women were enrolled, 97 were retained for 12 months, and sufficient NAF for analysis was available from 59 women at baseline, 49 at 6 months, and 50 at 12 months. Repeated measures mixed-model ANOVA was used to model the data using cholesterol levels and lactation duration as covariates, where appropriate. The high fruit-vegetable intervention, regardless of fat intake, significantly increased total carotenoid levels in NAF. In the low-fat arm, levels of total carotenoids decreased over time relative to control. Levels of total tocopherols and retinol did not change significantly. Levels of 15-F(2t)-isoprostane, a marker of lipid peroxidation, also did not change significantly over time, although there was a decrease observed in the combination arm.

CONCLUSIONS

These results indicate that total carotenoid levels in NAF can be significantly increased in the breast NAF with a high fruit-vegetable diet. A low-fat diet that was achieved with little increase in fruit and vegetable intake, however, decreased NAF carotenoid levels.