Benign Breast Tissue Sampling for Prevention Studies

Gene expression in breast and adipose tissue after 12 months of weight loss and vitamin D supplementation in postmenopausal women

Adipose tissue is involved in the etiology of postmenopausal breast cancer, possibly through increased sex steroid hormone production, inflammation, and altered adipokines. Vitamin D may affect these pathways but its effect on gene expression in different tissues has not been examined. Within a double-blind, 12-month placebo-controlled randomized trial, we compared 2000 IU/day oral vitamin D₃ supplementation (N = 39) vs. placebo (N = 40) on the expression of 5 genes in breast and adipose tissue in overweight/obese postmenopausal women (50-75 years). All participants had serum 25-hydroxyvitamin D (25(OH)D) levels ≥ 10-<32 ng/mL ("insufficient") and concurrently completed a behavioral weight loss program. Random periareolar fine needle aspiration (RPFNA) and abdominal subcutaneous adipose tissue biopsies were performed at baseline and 12 months. Changes in expression of aromatase (CYP19A1), peroxisome proliferator-activated receptor gamma (PPARG), adiponectin (ADIPOQ), monocyte-chemoattractant protein 1 (MCP-1), and vitamin D receptor (VDR) were analyzed by qRT-PCR. Compared to placebo, 2000 IU vitamin D did not show significant effects on gene expression in breast or adipose tissue. Replete women (i.e., 25(OH)D ≥ 32 ng/mL; N = 17) showed a small decrease in MCP-1 expression compared to an increase among women who remained 'insufficient' despite supplementation (N = 12) (Replete:-1.6% vs. Non-replete: 61.2%, p = 0.015) in breast, but not adipose tissue. No statistically significant differences in gene expression were detected according to degree of weight loss. Vitamin D repletion during weight loss may have different effects on gene expression in breast and adipose tissue. Further research on the localized effects of vitamin D is needed to determine its effect on breast cancer risk.

Exemestane Use in Postmenopausal Women at High Risk for Invasive Breast Cancer: Evaluating Biomarkers of Efficacy and Safety

This phase II trial evaluated clinical markers of efficacy and safety of exemestane in postmenopausal women at increased risk for breast cancer. Postmenopausal women (n = 42) at risk for invasive breast cancer received 25 mg exemestane daily for 2 years along with calcium and vitamin D. The primary outcome was change in mammographic density (MD) after one year. Secondary outcomes included change in serum steroid hormones as well as change in trefoil protein 1 (TFF1) and proliferating cell nuclear antigen (PCNA) in breast tissue. Safety and tolerability were also assessed. MD decreased at 1 year and was significant at 2 years [mean change = -4.1%; 95% confidence intervals (CI), -7.2 to -1.1; P = 0.009]. Serum estradiol and testosterone levels significantly decreased at 3 months and remained suppressed at 12 months. After 1 year of treatment, TFF1 intensity decreased (mean change -1.32; 95% CI, -1.87 to -0.76; P < 0.001). Exemestane was safe and well tolerated. Exemestane decreased MD and expression of breast tissue TFF1. It was well tolerated with few clinically relevant side effects. MD and breast tissue TFF1 are potential biomarkers of breast cancer-preventive effects of exemestane in high-risk postmenopausal women.

Breast Cancer Risk Assessment and Risk Reduction

Until recently, the primary message of breast health awareness programs was that early detection is a woman's best protection against breast cancer, because there was no way to prevent it. Currently, however, tamoxifen is approved for chemoprevention of breast cancer in high-risk women, and studies are underway evaluating other medications that may decrease breast cancer risk. Data have also become available regarding the efficacy of surgical strategies to reduce breast cancer risk. Any prevention method, however, will have associated risk of complications or adverse effects, and determining the net risk/benefit ratio depends on the ability to accurately quantify a woman's baseline likelihood of developing breast cancer. This article reviews available methods for assessing and reducing breast cancer risk.

Optimization of estrogen receptor analysis by immunocytochemistry in random periareolar fine-needle aspiration samples of breast tissue processed as thin-layer preparations

Immunostaining of estrogen receptor alpha (ER) in samples of benign breast tissue obtained by random periareolar fine-needle aspiration (RPFNA) is a practical tool for breast cancer chemoprevention trials. The authors report an optimized method of ER immunostaining for use with thin-layer preparations of modified Cytolyt-fixed benign breast tissue acquired by RPFNA. Samples of benign breast tissue and MCF-7 controls processed as thin-layer preparations were tested for the effects of antibody titer, antigen retrieval temperature (90 degrees or 115 degrees C), buffer (20% nuclear decloaker, pH 9.3; 10 mM citrate buffer, pH 6), and blocking solution (0.01% glucose oxidase or 0.3% H2O2) on ER immunostaining. The prevalence of positively stained breast epithelial cells, mean intensity of ER staining, and composite immunostaining score were evaluated for effect of immunostaining protocol. RPFNA samples and MCF-7 cells processed using nuclear decloaker and low-temperature antigen retrieval had more ER-positive cells (P<0.0001) and increased mean staining intensity and weighted staining indices (P<0.05) compared with samples prepared with citrate buffer and high-temperature antigen retrieval. Glucose oxidase increased ER-positive cells in comparison to hydrogen peroxide (P<0.04) when combined with low-temperature antigen retrieval and the use of nuclear decloaker. Staining was negative for all non-immune controls regardless of protocol. The combination of low-temperature antigen retrieval, diluted commercial nuclear decloaker solution, and a glucose oxidase blocking step yielded optimal ER immunostaining for thin-layer preparations of benign breast tissue harvested by RPFNA.

Oestrogen/insulin-like growth factor-I receptor interaction in early breast cancer: clinical implications

The expression of oestrogen receptor (ER) and that of the insulin-like growth factor-I receptor (IGF-IR) are positively correlated in breast cancer specimens. Their function is strongly linked in enhancing proliferative activity in normal and malignant human mammary epithelial cells in culture. This review examines the likely role of such a mechanism in the increased breast cancer risk reported in postmenopausal women with abdominal obesity. Precancerous breast lesions show an increased proportion of ER-positive cells with high proliferative activity, and recent studies suggest that genetic mutations or epigenetic variants in the ER alpha gene may increase the ER's sensitivity to oestrogen stimulation. Abdominal obesity in women is associated with higher concentrations both of free oestradiol and free IGF-I. Activation of their respective receptors may induce synergistic stimulation of mammary carcinogenesis. However, there is clinical evidence that progression in precancerous breast lesions may be delayed or reversed. Involution occurs spontaneously in a proportion of duct carcinoma in situ (DCIS) (intraductal) lesions as women approach the menopause, and antioestrogen therapy has been shown to reduce recurrence and progression of DCIS lesions.

CONCLUSIONS

Intervention trials in breast cancer prevention would greatly benefit from surrogate response markers which could predict long-term benefit. Changes in ER and IGF-IR expression apart from those in standardised cytomorphological criteria, might predict the likelihood of DCIS involution in cancer prevention trials. Future studies could involve examination of serial core biopsies from normal breast tissue during trials of antioestrogens, retinoids or weight-reduction interventions. Correlation of changes in these markers with changes in circulating IGF-I and oestradiol concentrations may help to clarify the roles of the markers.