Association of breast fluid coloration with age, ethnicity, and cigarette smoking

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.

Weight loss reduces breast ductal fluid estrogens in obese postmenopausal women: a single arm intervention pilot study

BACKGROUND

Accumulation of excess body fat increases breast cancer risk after menopause. Whether the localized breast is differently influenced by adipose tissue compared to the rest of the body, has not been well studied. Our purpose was to demonstrate feasibility and preliminarily evaluate serum-based and localized breast biomarker changes resulting from a weight loss intervention among obese postmenopausal women.

METHODS

We conducted a 12-week pilot controlled dietary and exercise intervention among healthy obese postmenopausal women, collected serum and breast ductal fluid before and after the intervention, and estimated the association with systemic and localized biomarker changes. We recruited 7 obese (mean body mass index = 33.6 kg/m2) postmenopausal women. We collected samples at baseline and the 12th week for: anthropometry; phlebotomy; dual-energy x-ray absorptiometry (lean and fat mass); exercise fitness (maximum oxygen consumption (VO2Max); 1-repetition strength maximum); and breast ductal lavage.

RESULTS

Changes from baseline occurred in body composition and exercise performance including fat mass loss (14% average drop), VO2Max (+36% increase) and strength improvement (+26%). Breast ductal fluid markers declined from baseline with estradiol showing a 24% reduction and IL-6 a 20% reduction. We also observed serum biomarker reductions from baseline including leptin (36% decline), estrone sulfate (-10%), estradiol (-25%), and Il-6 (-33%).

CONCLUSIONS

Conduct of the diet and exercise intervention, collection of ductal fluid, and measurement of hormones and cytokines contained in the ductal fluid were all feasible. We preliminarily demonstrated estradiol and IL-6 reductions from baseline in both serum and breast ductal fluid among obese postmenopausal women who participated in the 12-week weight loss diet and exercise intervention.

Perspectives of breast cancer etiology: synergistic interaction between smoking and exogenous hormone use

To explore breast cancer etiology, literature was searched using Medline. We explored the 1) plausibility of smoking in breast carcinogenesis; 2) physiological properties, susceptibility windows, and exposure timing of breast cells; 3) role of exogenous hormones in breast carcinogenesis; 4) biological mechanism of synergistic interactions between smoking and exogenous hormones in breast carcinogenesis; and 5) evidence from epidemiologic studies and the fitted secular trend between smoking rate, exogenous hormone use, and breast cancer incidence in past decades. We deduced that exogenous hormone use per se is not a significant cause and its association with breast cancer is distorted by chronic exposure to environmental carcinogens, especially smoking. We hypothesize that smoking is one of the causes of breast cancer and that this causality is strengthened by synergistic interaction between smoking and exogenous hormone use. Physicians should be cautious of prescribing exogenous hormones for those with chronic exposure to environmental carcinogens to prevent breast cancer.

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.

Nipple aspirate fluid color is associated with breast cancer

BACKGROUND

Fluid can be non-invasively aspirated from the breast nipple (nipple aspirate fluid, NAF). NAF may have many colors, including clear, white, yellow, green, and red/brown. While bloody spontaneous nipple discharge has been linked with breast cancer, the association of NAF color with cancer is not established. Our hypothesis was that red/brown NAF color was associated with breast cancer. The purpose of this study was to assess (1) if red/brown NAF is associated with the presence and progression of breast cancer, (2) the influence of prior needle or surgical biopsy on NAF color, and (3) if an association between NAF color and breast cancer was found, to develop a cancer predictive model including NAF color and cytology, and clinical information.

METHODS

Specimens were obtained from 848 breasts between 1999 and 2004 after subjects enrolled in an IRB approved protocol to evaluate biologic markers of breast cancer. Cytologic evaluation was performed on Papanicolaou-stained cytospin preparations of NAF.

RESULTS

Red/brown NAF was associated with breast cancer when considering all samples (p<0.001) and samples from women who did not undergo recent surgery (p=0.005). Needle biopsy did not, but surgical biopsy did influence NAF color. For the 327 women with NAF collected from both breasts, there was a significant association between red/brown NAF color and the presence of breast cancer (p=0.005). Red/brown NAF was more common in breasts with ductal carcinoma in situ than atypical hyperplasia (p=0.008). The optimal model, included NAF color, cytology, and age, was 92% sensitive and 61% specific in predicting if a woman had breast cancer.

CONCLUSIONS

NAF color was associated with the presence of breast cancer and the progression from precancer to cancer in a population of women who presented to a breast cancer evaluation clinic. NAF color contributed to a highly predictive breast cancer detection model. Additional studies are warranted to determine the usefulness of NAF color in the assessment of women who present for breast cancer evaluation.

Influence of Lactation History on Breast Nipple Aspirate Fluid Yields and Fluid Composition

Analysis of nipple aspirate fluid (NAF) can be useful for understanding the impact that various lifestyle factors have on the biology of the breast. In this study, breast NAF was obtained at baseline from premenopausal women who volunteered for a dietary intervention trial. The influence of lactation history on both fluid yields and fluid composition was explored. We examined the levels of fat-soluble micronutrients (tocopherols, carotenoids, retinol), one lipid oxidation product (8-isoprostane), cholesterol, and protein in NAF. Roughly half of the women in the trial had never lactated, but this did not affect fluid yields appreciably. Carotenoid and tocopherol levels were significantly higher in NAF from women who lactated 6 months or more versus women who had lactated for shorter periods of time or never, but 8-isoprostane, protein, and cholesterol levels were not affected appreciably by lifetime lactation history. Longer times after weaning were associated with higher cholesterol levels, and there also was a suggestion the fat-soluble micronutrients declined with time after weaning. This is of interest since high cholesterol levels in breast fluid have been associated with an increased breast cancer risk, while carotenoids and tocopherols are thought to be protective. The results of this study provide further evidence of the potential benefits of prolonged lactation via its influence on NAF composition.

Presence of carotenoid, an anticarcinogenic marker, in nipple aspirates postlactation

Case-controlled studies have identified a protective effect of lactation against breast cancer; however, little is known about the nature of this protective mechanism. The purpose of this study was to examine postweaned, nipple aspirate fluid (NAF) from women, ages 18 to 45, for carotenoid, a known antioxidant and anticarcinogenic marker, and compare carotenoid availability in NAF with that reported in colostrum. Women who had lactated at least 6 months and weaned for at least 6 months were recruited into the study A prestudy and poststudy serum prolactin level was obtained. NAF was obtained through a nipple aspirator method. Total carotenoid ranged from 0.4 to 4.0 microg/mL, with a mean level of 1.9+/-1.2 (SD). Women who had weaned earlier (<12mo) had significantly more carotenoids than those who had lactated longer (>12mo) (P = 0.04). These levels were similar to those known to occur in colostrum. This research elucidates possible mechanisms of the protective effect of lactation on the microenvironment of the breast.

Factors associated with obtaining nipple aspirate fluid: analysis of 1428 women and literature review

Studies of cytologic and biochemical constituents of nipple aspirates of breast fluid have contributed to understanding the natural history of benign and malignant breast disease. We conducted multivariate analyses using 1428 women from a recent case-control study of breast disease to determine which factors were independently associated with the ability to obtain breast fluid from nonlactating women. We then compared results from these analyses to the results from five previous studies that also used the aspiration technique of Sartorius. Four factors were consistently associated across studies with increased ability to obtain breast fluid: 1) age up to 35 to 50 years; 2) earlier age at menarche; 3) non-Asian compared to Asian ethnicity; and 4) history of lactation. Exogenous estrogen use, endogenous estrogen concentrations, phase of menstrual cycle, family history of breast cancer, type of menopause, and less than full-term pregnancy consistently did not influence ability to obtain fluid. New findings from this study shed light on some apparently contradictory findings from the previous studies. In particular, this study showed that the effects of age on ability to obtain fluid appeared to be independent of the effects of menopause. Furthermore, discrepancies in previous findings on the effects of parity on ability to obtain fluid may be explained by our finding that the increased ability to obtain fluid from parous compared to nulliparous women applied only to parous women who had breastfed.

Nipple aspirate fluids in adult nonlactating women--lactose content, cationic Na+, K+, Na+/K+ ratio, and coloration

The presence of lactose in nipple secretions is considered biochemical evidence of breast secretory activity, and has been reported to occur more frequently in white compared to brownish or green colored breast fluid. We studied lactose, Na+, and K+ concentrations, the Na+/K+ ratio, and the coloration of nipple aspirate fluid (NAF) from 49 nonpregnant women. A significant relationship was found between the concentrations of lactose, Na+, and K+, and age and the coloration of NAF. Lactose was present in 22/49 (44.8%) of the NAF samples and declined with age from 100% positivity in women less than or equal to 29 years to 29% in those less than or equal to 35 years. In NAF of deep yellow, brown and green colorations, only traces of lactose were found. Na+ and K+ increased with age and with darker colorations compared to white, pale yellow, or colorless NAF. Lactose was present in NAF samples from both parous and nulliparous younger women, indicating that the breasts of many nonpregnant women respond to prolactin stimulation; hence, lactose may provide a simple marker indicating active physiologic secretory activity of the breast. As reported previously, NAF of darker coloration, containing elevated levels of cholesterol, cholesterol oxidation products, and other substances, suggests retention and impaired reabsorption of these and other products of secretion. Because of the secretion and temporary retention by the breast glands of chemical substances of exogenous and endogenous origin, including mutagens and carcinogens, lactose concentration and coloration of NAF may be useful as markers of secretion and reabsorption in future physiologically based clinical and epidemiologic studies of the pathogenesis of breast disease.