Evidence for a tumour suppressive function of IGF1-binding proteins in human breast cancer

The role of the insulin like growth factor (IGF) system in various human malignancies has been well established. The aim of this study was to determine the levels of mRNA expression of insulin-like growth factor-binding protein (IGFBP)-1, -3 and -7 genes in benign and malignant breast tissue and explore their relationship with various prognostic parameters.

MATERIALS AND METHODS

Breast cancer tissue (n=127) and normal background tissue (n-33) were prospectively collected and analysed for levels of IGFBP-1, -3 and -7 mRNA using real-time Q-PCR. mRNA levels were then analysed against tumour grade, nodal status, Nottingham prognostic index (NPI)/TNM stage and tumour type.

RESULTS

For IGFBP-1 and -3, mRNA expression was higher in normal tissue. This was significant for IGFBP-1 when comparing NPI 3 with NPI 1 (p=0.050) and the normal group (p=0.040). With respect to TNM analysis, there was less IGFBP-1 mRNA when comparing TNM 3 with normal (p=0.017), TNM 1 (p=0.047) and TNM 2 (p=0.019) tumours. This was also found when comparing TNM 4 samples with normal tissue (p=0.017), TNM 1 (p=0.046) and TNM 2 (p=0.019). For IGFBP-3 mRNA, there was less mRNA when comparing TNM 3 with TNM 1 (p= 0.017) and TNM 2 (p=0.050), and also less mRNA expression when comparing TNM 4 with TNM 1 (p=0.030). For IGFBP-7 mRNA, both TNM 1 (p=0.0077) and TNM 2 (p=0.015) had significantly more expression than TNM 3 samples.

CONCLUSION

This study supports the role of IGFBP-1, -3 and -7 as potential tumour suppressor genes in human breast cancer.

Management of gynaecomastia: an update

Gynaecomastia, a benign enlargement of the male breast as a result of proliferation of the glandular component, is common, being present in 30-50% of healthy men. It may be an incidental finding, an acute unilateral or bilateral tender breast enlargement or a progressive painless enlargement of the male breast. A general medical history and careful physical examination, looking for features suggestive of breast cancer, often suffice for evaluation in patients without symptoms or those with incidentally discovered breast enlargement. If the gynaecomastia is of recent onset, a more detailed evaluation, including selected laboratory tests to search for an underlying cause is necessary. Treatment depends on the cause: an offending drug may need to be withdrawn or alternatively radiation, surgery and/or medical therapy may be necessary. The use of a combination of surgical excision and liposuction through a periareolar incision represents the surgical approach of choice.

HTERT mRNA expression correlates with matrix metalloproteinase-1 and vascular endothelial growth factor expression in human breast cancer: a correlative study using RT-PCR

BACKGROUND

Telomerase activity has been significantly associated with nodal metastasis and cellular proliferation in human breast cancer, indicating that its degree of expression has some form of vital control over the invasive nature of the malignancy concerned. Of the telomerase subunits, the reverse transcriptase (hTERT) is the main determinant of enzyme activity. Vascular endothelial growth factors (VEGF)-C and (VEGF)-D, matrix metalloprotease type 1 (MMP-1) and protease-activated receptors (PARs) have all been linked to promotion of tumour invasiveness and metastatic dissemination. This study aims to examine the association between hTERT transcription and that of VEGF-D, VEGF-C, MMP-1, PAR1a and PAR1b through a correlative analysis of the mRNA transcripts of these genes in human breast cancer.

MATERIALS AND METHODS

Breast cancer tissues (n = 116) and normal tissues (n-31) were collected immediately after surgery and stored at -80 degrees C until use. The level of hTERT transcripts from the prepared DNA from the above samples was determined using real time-quantitative PCR based on the Amplifluor technology. The levels of the transcript were generated from a standard that was simultaneously amplified with the samples. Normalisation against cytokeratin 19 (CK19) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was also carried out.

RESULTS

There was a positive correlation between hTERT mRNA expression (after CK19 normalisation) with both VEGF-D and MMP-1 in human breast cancer. PAR1 was seen to correlate with hTERT (after GAPDH normalisation) with a highly significant correlation with PAR1a alone. However there was no correlation between hTERT transcription and VEGF-C or with PAR1b alone.

CONCLUSION

Our findings suggest that hTERT is a potential up-regulator of MMP-1, PAR1 and VEGF-D expression and this may explain its apparent control over the invasiveness and metastasis of the malignancy concerned.

The potential clinical applications of insulin-like growth factor-1 ligand in human breast cancer

Insulin-like growth factor-1 (IGF-1) has become recognized as a growth factor with pro-mitogenic and antiapoptotic effects on a variety of human cells. This article reviews the potential role of IGF-1 ligand in the clinical management of breast cancer patients. Many studies have shown that IGF-1 acts synergistically with oestrogen to stimulate breast cancer cells. Case-control studies have also demonstrated that premenopausal women with high levels of serum IGF-1 have an increased risk of developing breast cancer later in life. Serum IGF-1 levels can therefore be used as a potential biomarker for predicting breast cancer risk. Furthermore, there is evidence that serum IGF-1 levels can serve as a response biomarker in chemoprevention drug trials. The role of IGF-1 expression in breast cancer tissue as a prognostic marker is not clearly established. Identifying the IGF-1 gene polymorphism can potentially be used in predicting breast cancer risk.

hTERT mRNA expression is associated with a poor clinical outcome in human breast cancer

BACKGROUND

Telomerase is a ribonucleoprotein enzyme that synthesises telomeres after cell division and maintains chromosomal length and stability thus leading to cellular immortalisation. hTERT (human telomerase reverse transcriptase) gene is the rate-limiting determinant of telomerase reactivation. The present study aims to quantitatively measure the expression of hTERT mRNA in human breast cancer, examine the association between hTERT and the clinicopathological characteristics of the cancer specimens including the Nottingham Prognostic Index (NPI) and to explore the relationship between hTERT expression and clinical outcome.

MATERIALS AND METHODS

RNA was extracted from 116 breast carcinomas and 31 matched adjacent non-cancerous tissue (ANCT). hTERT mRNA expression was estimated by reverse transcriptase-PCR (RT-PCR) and Taqman methodology.

RESULTS

hTERT mRNA was present in all of the cancerous specimens (mean=0.1701, median=0.0205) and most ANCT specimens with levels being 2.6 times higher in the cancerous tissue than in ANCT (mean=0.156 vs. 0.68, p=0.18). The mean mRNA levels increased with NPI scores (0.0816 for NPI 1, 0.1186 for NPI 2 and 0.68 for NPI 3), however this failed to reach statistical significance (P-values= 0.33 for NPI 1 vs. 2, 0.27for NPI2 vs. 3 and 0.24 for NPI 1 vs. 3). hTERT levels also increased with increasing tumour's grade (mean= 0.0459 for grade 1, 0.111for grade 2, and 0.27 for grade 3) but this trend did not reach a statistical significance. Low levels of hTERT were associated with mucinous carcinoma compared with ductal (p=0.023) and lobular (p=0.021) types. hTERT mRNA levels were higher in patients who had recurrent disease or died from breast cancer compared with those who remained alive without disease after a median follow up of 6 years (p=0.0026).

CONCLUSION

High hTERT mRNA levels are associated with a poor clinical outcome in human breast cancer and should be included as a prognostic marker in future validation studies.

The role of STS and OATP-B mRNA expression in predicting the clinical outcome in human breast cancer

BACKGROUND

Steroid sulfatase (STS) is the enzyme responsible for hydrolysing biologically inactive estrogen sulfates to active estrogens. Therefore it plays a significant role in supporting the growth of hormone-dependent tumours of the breast, endometrium and prostate. OATP-B is a member of a family of membrane transporter proteins that regulates the uptake of steroid sulfates through cell membranes. Our objective was to determine, using quantitative PCRA whether the mRNA expression levels from these genes were positively correlated with clinical outcome in human breast cancer. This is the first study in the literature to examine the relationship between STS and OATP-B in human breast cancer and to investigate the potential prognostic value of OATP-B.

MATERIALS AND METHODS

A total of 153 samples (120 tumour tissues and 33 normal breast tissues) were analysed. The levels of transcription of STS and OATP-B were determined using real-time quantitative PCR and normalized against cytokeratin 19. The levels of expression were analysed against tumour's stage, grade, nodal status, local relapse, distant metastasis, ERalpha, ERbeta and HER1-4 receptor status and survival over a 10 year follow up period.

RESULTS

The levels of STS mRNA were significantly higher in malignant samples (p=0.031) and in node positive disease (p=0.0222). STS mRNA expression increased with increasing tumour grade but this did not reach statistical significance. A significant increase was also noted in levels correlating with tumour stage when stages TNM1 and TNM2, TNM2 and TNM3, and TNM3 and TNM4 (p=0.00001, 0.0017 and 0.02, respectively) were compared. Furthermore, STS expression levels positively correlated with progression of disease, as levels were significantly higher in samples from patients who developed metastasis, local recurrence, or died of breast cancer when compared to those who were disease free for >10 years (p=0.0036). No significant correlation was found between the levels of STS expression and ERalpha/ERbeta/ status. The levels positively correlated with HER1 and HER3 receptors. The levels of mRNA expression of OATP-B were higher in malignant tissue compared to normal tissue; this, however, did not reach statistical significance (p=0.4045). Levels were also higher in node positive disease (p=0.0672). Expression levels increased with increasing tumour grade and this became statistically significant when comparing grade 1 to 2, and grade 2 to 3 (p=0.0271 and 0.0289, respectively). An increase in levels correlating with TNM tumour staging was also observed; this, however, did not reach statistical significance. There was no significant correlation between OATP-B expression levels and clinical progression of breast cancer. No correlation was found between STS and OATP-B expression levels.

CONCLUSION

This study demonstrates a compelling trend for STS transcription levels to be higher in cancer tissues and in patients who developed progressive disease. OATP-B expression levels correlated with the grade and stage of the disease, but not with the clinical outcome. These results suggest that STS mRNA has a significant potential as an important predictor of clinical outcome in patients with breast cancer.

Breast cancer risk in flight attendants: an update

Although further research is required, epidemiological evidence indicates that breast cancer risk is increased by 40% among flight attendants. Female flight attendants and women who fly frequently should be informed of this potential increase in risk and be encouraged to participate in appropriate breast cancer screening programs.

Does mammary ductoscopy have a role in clinical practice?

BACKGROUND

Mammary ductoscopy (MD) is a newly developed endoscopic technique that allows direct visualisation of the mammary ductal epithelium using sub-millimetre fiberoptic microendoscopes inserted through the ductal opening onto the nipple surface. These scopes also provide working channels for insufflation, irrigation, ductal lavage, and possible therapeutic intervention. MD can be performed under local anaesthesia in the office setting. The objective of this study is to assess the technical feasibility of mammary ductoscopy, and examine its role in guiding ductal excision surgery and the early diagnosis of malignancy.

METHODS

Mammary ductoscopy (MD) was performed using a 1 mm fiberoptic microendoscope (Mastascope TM) in 26 patients (age range: 14-73 years): 13 patients undergoing mastectomy (n = 12) or lumpectomy (n = 1) for ductal carcinoma (including 12 cases of DCIS and one case of infiltrating ductal carcinoma) and 13 patients with pathological nipple discharge (PND) and benign breast imaging and simple discharge cytology. Of the latter group: 10 procedures were performed under local anaesthesia (LA) in the office setting and 3 procedures were carried out under general anaesthesia (GA) to guide duct excision surgery. The ductoscopic appearances in this group were graded between 0 and 5 (D0-D5) according to the degree of suspicion.

RESULTS

Intraoperative MD was accomplished in 11 (84.6%) of 13 patients undergoing surgery for DCIS. MD was unsuccessful in 2 cases: one patient (aged 73 years) had sclerosis of the nipple and one patient had preoperative vital blue injection in the subareolar region as part of the sentinel node biopsy thus resulting in inadequate visualisation. Intraductal pathology was visualised in 8 (80%) of the 10 cases undergoing mastectomy but ductoscopic cytology was positive for malignancy in only 2 cases (sensitivity = 16%, specificity = 100%). In the office setting, MD was accomplished in 9 (90%) out of 10 patients with PND and was well tolerated (mean pain score = 3.8 out of 10: range 0-7). Of these 10 patients; MD was inadequate (D0) in one patient due to complete occlusion of lumen by the lesion, showed a papilloma in 3 patients (D3), duct ectasia (D2) in 3 patients, irregular thickening of the lumen suspicious of DCIS (D4) in one patient and non-specific benign findings (D2) in 2 patients. Three women with benign ductoscopy and ductoscopy-assisted cytology were reassured and treated conservatively. The remaining 7 patients had ductoscopy-guided duct excision which revealed DCIS in one, papilloma in 4 and benign breast disease in 2 patients. Adequate cellular yield was obtained in 7 (70%) out of 10 cases (benign cytology). The three patients who had MD under GA during microdochectomy had benign endoscopic appearances and final histology (one papilloma and 2 cases of duct ectasia).

CONCLUSION

MD is technically feasible in most patients and has a potential in the early detection of breast cancer. The procedure can be performed safely in the office setting and should be considered in all patients presenting with a single duct PND. MD has the potential to reduce the number of duct excision procedures and minimise the extent of surgical resection. Ductoscopic cytology is not sufficiently sensitive for the diagnosis of malignancy and the development of a biopsy tool that obtains tissue under direct visualisation is required.

Oncological considerations of skin-sparing mastectomy

Aim

To review evidence concerning the oncological safety of performing skin-sparing mastectomy (SSM) for invasive breast cancer and ductal carcinoma in situ (DCIS). Furthermore, the evidence concerning RT in relation to SSM and the possibility of nipple preservation was considered.

Methods

Literature review facilitated by Medline and PubMed databases.

Findings

Despite the lack of randomised controlled trials, SSM has become an accepted procedure in women undergoing mastectomy and immediate reconstruction for early breast cancer. Compared to non-skin-sparing mastectomy (NSSM), SSM seems to be oncologically safe in patients undergoing mastectomy for invasive tumours smaller than 5 cm, multicentric tumours, DCIS or risk-reduction. However, the technique should be avoided in patients with inflammatory breast cancer or in those with extensive tumour involvement of the skin in view of the high risk of local recurrence. SSM with nipple areola complex (NAC) preservation appears to be oncologically safe, provided the tumour is not close to the nipple and a frozen section protocol for the retro-areolar tissue is followed. Although radiotherapy (RT) does not represent a contraindication to SSM, the latter should be used with caution if postoperative RT is likely, since it detracts from the final cosmetic outcome.

The potential role of dynamic thermal analysis in breast cancer detection

BACKGROUND

It is presently well accepted that the breast exhibits a circadian rhythm reflective of its physiology. There is increasing evidence that rhythms associated with malignant cells proliferation are largely non-circadian. Cancer development appears to generate its own thermal signatures and the complexity of these signatures may be a reflection of its degree of development. The limitations of mammography as a screening modality especially in young women with dense breasts necessitated the development of novel and more effective screening strategies with a high sensitivity and specificity. The aim of this prospective study was to evaluate the feasibility of dynamic thermal analysis (DTA) as a potential breast cancer screening tool.

METHODS

173 women undergoing mammography as part of clinical assessment of their breast symptoms were recruited prior to having a biopsy. Thermal data from the breast surface were collected every five minutes for a period of 48 hours using eight thermal sensors placed on each breast surface [First Warning System (FWS), Lifeline Biotechnologies, Florida, USA]. Thermal data were recorded by microprocessors during the test period and analysed using specially developed statistical software. Temperature points from each contra-lateral sensor are plotted against each other to form a thermal motion picture of a lesion's physiological activity. DTA interpretations [positive (abnormal thermal signature) and negative (normal thermal signature)] were compared with mammography and final histology findings.

RESULTS

118 (68%) of participating patients, were found to have breast cancer on final histology. Mammography was diagnostic of malignancy (M5) in 55 (47%), indeterminate (M3, M4) in 54 (46%) and normal/benign (M1, M2) in 9 (8%) patients. DTA data was available on 160 (92.5%) participants. Using our initial algorithm, DTA was interpreted as positive in 113 patients and negative in 47 patients. Abnormal thermal signatures were found in 76 (72%) out of 105 breast cancer patients and 37 of the 55 benign cases. Then we developed a new algorithm using multiple-layer perception and SoftMax output artificial neural networks (ANN) on a subgroup (n = 38) of recorded files. The sensitivity improved to 76% (16/21) and false positives decreased to 26% (7/27)

CONCLUSION

DTA of the breast is a feasible, non invasive approach that seems to be sensitive for the detection of breast cancer. However, the test has a limited specificity that can be improved further using ANN. Prospective multi-centre trials are required to validate this promising modality as an adjunct to screening mammography especially in young women with dense breasts.

The role of aromatase and 17-β-hydroxysteroid dehydrogenase type 1 mRNA expression in predicting the clinical outcome of human breast cancer

INTRODUCTION

There is substantial evidence that breast cancer tissue contains all the enzymes responsible for the local biosynthesis of estrogens from circulating precursors. The cytochrome P-450 aromatase enzyme complex is responsible for the conversion of C19 androgens to estrogens and 17-beta-hydroxysteroid dehydrogenase (17-I(2)-HSD) type 1 catalyses the inter-conversion of estrone to the biologically more potent estradiol. The gene encoding for the cytochrome P-450 aromatase is known as CYP19 (15q21.2). It is well established that increased exposure to local estrogens is an important risk factor in the genesis and growth of breast cancer. The aim of this study is to investigate the relationship between CYP19 and 17-beta-HSD type 1A mRNA expression and clinico-pathological parameters of human breast cancer.

METHODS

One hundred and twenty seven tumor tissues and 33 normal tissues were analyzed. The levels of transcription of CYP19 and 17-beta-HSD type 1 were determined using real-time quantitative PCR. The mRNA expression was normalized against CK19. Levels of expression were analyzed against tumorâ's stage, grade, nodal status, local relapse, distant metastasis and survival over a 120A months follow up period. In addition, the levels were analyzed against estrogen receptor (ER) and HER1-4 status.

RESULTS

Overall, high tumor levels of mRNA expression of CYP19 and 17-beta-HSD type 1 correlated with poor survival (p=0.0105 and p=0.0182, respectively). Increased levels of CYP19 mRNA expression positively correlated with disease progression as levels were significantly higher in samples of patients who had distant metastasis and local recurrence and/or died of breast related causes when compared to those who were disease free for >10 years (p=0.0015). We also observed higher levels of CYP19 mRNA in tumor samples compared to normal breast tissue. However, this reached statistical significance only when comparing grade 1 tumors with normal tissue (p=0.01). There was no correlation between CYP19á mRNA expression and tumor stage, lymph node status and tumor grade. There was however a trend for a positive correlation between CYP19 and ER mRNA expressions (p=0.06). No significant difference in 17-beta-HSD type 1 expression between normal and cancerous tissues was observed. In tumor samples, we observed an increase in levels correlating with tumor's grade. This correlation was statistically significant when we compared grade 1 with grade 2 and grade 1 with grade 3 (p=0.0031 and 0.0251, respectively).

CONCLUSION

Our study shows that higher levels of the enzymes responsible for the local biosynthesis of estrogens especially aromatase are associated with a poor clinical outcome in patients with breast cancer.

Screening mammography in women aged 40-49: is it time to change?

There is little doubt that significant benefits can accrue from carrying out screening mammography of women aged 40–49 in the setting of a highly quality assured service delivery. This will best be achieved using digital mammography to maximise detection rates and trained and high volume reading expert radiologists to apply economic cushions of optimising specificity as well as sensitivity in addition to utilising modern and accurate assessment and tissue sampling techniques that have evolved.

Breast papillomas: current management with a focus on a new diagnostic and therapeutic modality

Breast papilloma is a term that describes an intraductal papillary configuration of the mammary epithelium on macroscopic or microscopic examination. It includes solitary intraductal papillomas, multiple papillomas, papillomatosis, and juvenile papillomatosis (JP).

Recent advances in mammary ductoscopy (MD) have raised new possibilities in the diagnosis and treatment of breast papillomas. This technique represents an important diagnostic adjunct in patients with pathological nipple discharge (PND) by allowing direct visualisation and biopsy of intraductal lesions and guiding duct excision surgery.

Treatment of breast papillomas often entails surgical duct excision for symptomatic relief and histopathological examination. Recently, more conservative approach has been adapted. MD-assisted microdochectomy should be considered the procedure of choice for a papilloma-related single duct discharge. Furthermore, there is increasing evidence that MD has the potential to reduce the number of duct excision procedures and minimise the extent of surgical resection. Imaging-guided vacuum-assisted core biopsy can be diagnostic and therapeutic for papillomas seen on mammography and/or ultrasound.

Patients with multiple papillomas do have an increased risk of developing cancer and should be kept under annual review with regular mammography (preferably digital mammography) if treated conservatively. Magnetic resonance (MR) can be also used in surveillance in view of its high sensitivity. Because the risk is small, long term and affects both breasts, long-term follow-up is more appropriate than prophylactic mastectomy. Patients who prove to have solitary duct papilloma have insufficient increase in the risk of subsequent malignancy to justify routine follow-up.

Insulin-like growth factor 1 (IGF-1) and its receptor mRNA levels in breast cancer and adjacent non-neoplastic tissue

Previous studies investigating the insulin-like growth factor 1 receptor (IGF-1R) expression in breast cancer tissue and adjacent non-neoplastic breast tissue (ANCT) have produced conflicting results. The IGF-1 and IGF-1R expression in pairs of breast cancer tissue and ANCT were investigated using RT-PCR and immunohistochemistry. The results of both methods were compared.

MATERIALS AND METHODS

IGF-1 and IGF-1R mRNA from 31 specimen pairs were estimated using RT-PCR. Immunohistochemistry for IGF-1R was carried out on 20 specimen pairs and the strength of staining was scored.

RESULTS

The mean relative IGF-1 mRNA level was lower in the cancerous tissue (mean 0.450 +/- 0.206) than in the ANCT (mean 0.632 +/- 0.384) (paired t-test, p = 0.001). There was no measurable difference in relative IGF-1R mRNA levels in the cancerous tissue (mean 0.146 +/- 0.08) and the ANCT (mean 0.14608 +/- 0.108) (paired t-test, p = 0.807). Using immunohistochemistry, there was no statistical difference (paired t-test, p = 0.910) in IGF-1R staining scores between cancer (mean 1.93) and ANCT (mean 1.90). The comparison between the two methodologies showed no correlation (Pearson's Correlation Coefficient = -0.393).

DISCUSSION

It can be concluded that IGF-1 expression is lower in cancerous tissue, thus supporting a paracrine relationship between cancerous tissue and ANCT, which may be useful in the prevention, diagnosis and treatment of breast cancer. There was no difference in the expression of the IGF-1 receptor in both types of tissue, as proven by RT-PCR and immunohistochemistty. Conflicting results in previous studies may be due to the different methods used to measure IGF-1R expression.

Skin and fat necrosis of the breast following methylene blue dye injection for sentinel node biopsy in a patient with breast cancer

Sentinel lymph node biopsy (SLNB) is a simple technique that uses subdermal or peri-tumoral injection of vital blue dye and/or radioactive isotope to identify the first lymph node(s) draining the primary tumor. It has been shown to accurately predict axillary node status in patients with clinically node negative breast cancer. The SLNB is emerging as a new standard of care in patients with early breast cancer. However, the use of methylene blue (MB) dye can be associated with a number of local complications due to its tissue reactive properties. We report a rare case of skin and fat necrosis followed by a dry gangrene of the skin in a female patient with breast cancer who underwent SLNB localization using peri-tumoral injection of MB dye in another institution. This case and literature review suggest that the use of MB dye for SLNB identification should be avoided and replaced with alternative types of blue dye such as Patent Blue V preferably in conjunction with a radioactive isotope tracer.

Is there a link between breast cancer and abortion: a review of the literature

The hormonal changes that take place in pregnancy cause breast tissue to proliferate and differentiate. Abortion interrupts this process and may leave the proliferated, undifferentiated breast tissue at higher risk of carcinogenesis. This review explains the supposed difference in effects of induced and spontaneous abortion upon the breast tissue and examines the literature for a link with breast cancer. Additional subcategories examined include parity, number of abortions, gestation, and maternal age at abortion. A comparison of retrospective and prospective studies is made and possible sources of bias are identified. There is no evidence to support a link between spontaneous abortion and breast cancer. Absence of a link with induced abortion is less clear, and further research should concentrate on investigating any relationship. We suggest that prospective research is used, with point of entry at first termination.

Dairy products and breast cancer risk: a review of the literature

BACKGROUND

Dietary elements and, in particular, dairy products have been implicated in the etiology of breast cancer. High saturated fat contents, contaminants such as pesticides, and insulin-like growth factor I (IGF-1) have been hypothesized as possible carcinogenic factors. In contrast, calcium, vitamin D, and conjugated linoleic acid (CLA) all are considered to reduce breast cancer risk. We aim to review the current epidemiological literature on the relationship between the intake of dairy products and breast cancer risk.

METHODS

A Medline search was conducted using the key words breast neoplasms and dairy products. Further articles were obtained by cross-matching references of relevant articles. Thirty-nine case-control and 11 cohort studies were identified since 1981. Two meta-analyses and several review articles were also noted.

RESULTS

Results from previous studies were analyzed and comparisons were made between each type of study. Controversy exists regarding this subject and we found conflicting evidence in recent literature regarding this hypothesis.

CONCLUSION

There is no substantial epidemiological evidence to support a significant link between the intake of dairy products and breast cancer risk.

Phytoestrogens and the risk of breast cancer: a review of the literature

BACKGROUND

Over the last decade, interest in the physiological role of bioactive compounds in plants has increased dramatically. Of particular interest in relation to human health are the class of compounds known as the phytoestrogens, which embody several groups of nonsteroidal estrogens that are widely distributed within the plant kingdom, including isoflavones and lignans. Epidemiological studies suggest that diets rich in phytoestrogens, particularly soy and unrefined grain products, may be associated with low risk of breast cancer. This review presents the studies published so far exploring a link between dietary phytoestrogens and breast cancer risk.

METHODS

A Medline search was conducted using the key words below. Further articles were obtained by cross-matching references of relevant articles. Twenty-one case-control and 15 prospective studies were identified since 1978. One meta-analysis and several review articles also were noted.

RESULTS

Results from previous studies were analyzed and comparisons were made between each type of study. Controversy exists regarding this subject, and we found conflicting evidence in recent literature regarding this hypothesis.

CONCLUSION

There is no clear evidence that phytoestrogen intake influences the risk of developing breast cancer.