Biologic activity of tamoxifen at low doses in healthy women

Predictive Effect of IGFBP-3 on Low-Dose Tamoxifen Efficacy in Noninvasive Breast Cancer in the Phase III Tam-01 Trial

PURPOSE

Low-dose tamoxifen 5 mg/day (babytam) for 3 years can decrease the incidence of new breast cancer events in women with breast intraepithelial neoplasia by 42% with limited toxicity, which provides a new treatment option for these disorders. However, predictive biomarkers of babytam efficacy are lacking. We studied whether baseline levels of insulin-like growth factor-1 (IGF-I), IGF-binding protein-3 (IGFBP-3), estradiol, and sex hormone-binding globulin (SHBG) and their ratios predict babytam efficacy on breast cancer events in a preplanned secondary analysis.

PATIENTS AND METHODS

Within a 1:1 placebo-controlled, multicenter randomized trial of babytam or placebo administered for 3 years after surgery in women with hormone-sensitive or unknown breast intraepithelial neoplasia, including atypical ductal hyperplasia and lobular or ductal carcinoma in situ, 406 of 500 participants consented to blood sampling at baseline and at 1 and 3 years. Serum IGF-I, IGFBP-3, estradiol, and SHBG levels and their ratios were measured using chemiluminescent immunoassays. Biomarker changes were estimated using mixed-effects models, and incidence rate ratios were calculated after 10 years of follow-up with Poisson regression. Subgroup analyses were performed using an interaction test and subpopulation treatment effect pattern plot.

RESULTS

Baseline levels of IGFBP-3 in the three top quartiles (≥3.44 µg/mL), but not in the lower quartile, predicted greater babytam efficacy compared with placebo (Pinteraction = 0.006). Baseline IGF-I, estradiol, or SHBG levels were not predictive of babytam efficacy, whereas the IGF-I/IGFBP-3 ratio was borderline significant (Pinteraction = 0.067).

CONCLUSIONS

High baseline levels of IGFBP-3 (≥3.44 µg/mL) predicted babytam efficacy and may help differentiate which women benefit most from this treatment.

Chemoprevention strategies in hereditary breast and ovarian cancer syndromes

Hereditary breast and/or ovarian cancer syndromes are inherited disorders in which there is an increased risk of developing breast and/or ovarian cancer in the lifetime, usually at a younger age compared to the general population. Cancer prevention in these syndromes includes prophylactic surgeries, personalized surveillance programs and chemopreventive strategies. Chemoprevention exploits the use of certain drugs or other substances to help lower the risk of developing cancer. In this context, tamoxifen was the first agent considered for breast cancer prevention, followed by raloxifene and the third-generation aromatase inhibitors. On the other hand, the first and most widespread type of chemoprevention for ovarian cancer was combined hormonal contraceptive use. Although several strategies have been studied and showed promising results, only a few of these are currently applied in daily clinical practice. Side effects along with several psychological variables such as cancer perceived risk, worries and related distress, strongly influence women's decision on chemoprevention. The present review explores and summarizes the available evidence on breast and ovarian cancer chemoprevention approaches.

Protective role of olive oil extract of propolis on short and long-term administration of tamoxifen in rats

Tamoxifen (TAM) is an antiestrogenic agent used for adjuvant treatment in estrogen receptor-positive breast cancers in the pre/post-menopausal period. This study, it was aimed to determine the effect of olive oil extract of propolis (OEP) on short and long-term administration of TAM in rats. Wistar albino rats were divided into groups with eight animals in each. Groups: control, OEP, TAM, and OEP + TAM. At the end of the experiment, oxidative stress tests were performed with Enzyme-Linked ImmunoSorbent Assay (ELISA) on blood and tissue samples (liver, kidney, and ovary) taken from rats. After single-dose TAM administration, there was a significant increase in red blood cell, hematocrit, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration levels compared to the control group, a decrease in low-density lipoprotein (LDL) value, a significant increase in liver enzymes and fasting glucose values was detected compared with the control and propolis groups. A normalizing effect was observed in the group given OEP and TAM combined. The increase in Malondialdehyde (MDA) and the decrease in enzyme activities in tissues are also noteworthy. Propolis application reduced the tissue damage caused by TAM. In addition, improved cytokine levels, which increased with TAM administration. It has been concluded that OEP can be given in supportive treatment, as it improves hematological and antioxidant parameters in TAM treatment.

Risk of Cardiovascular Events and Lipid Profile Change in Patients with Breast Cancer Taking Aromatase Inhibitor: A Systematic Review and Meta-Analysis

Cardiovascular disease (CVD) is one of the most common comorbidities in breast cancer survivors. Recently, the target population and treatment period for aromatase inhibitor (AI) treatment in breast cancer patients has been expanding. However, information on adverse CVD events from the long-term use of AI is still lacking. The aim of this study was to investigate the CVD side effects of AI treatment and to evaluate the changes in lipid profile during AI treatment. A systematic search of PubMed (Medline), EMBASE, and Cochrane Library databases reporting on cardiovascular outcomes or lipid profiles change in adult female breast cancer patients (>19 years old) with AI was performed. The pooled analysis of 25 studies showed that the prevalence rate of any type of cardiovascular disease was 6.08 per 100 persons (95% CI 2.91-10.31). Angina was the most common type of heart-related cardiovascular event accounting for 3.85 per 100 persons, followed by any type of stroke (3.34) and venous thromboembolism (2.95). Ischemic stroke (OR 1.39, 95% CI 1.07-1.81) and myocardial infarction (OR 1.30, 95% CI 0.88-1.93) were more common in AI compared with tamoxifen, whereas the prevalence of venous thromboembolism (OR 0.61, 95% CI 0.37-1) was significantly lower in the AI group. In addition, treatment with AI for 6-12 months showed a decrease in HDL-cholesterol and an increase in LDL-cholesterol and total cholesterol. Various CVDs can occur when using AI, and in particular, the risk of MI and ischemic stroke increases in comparison with the adverse effect of tamoxifen. The occurrence of CVD might be related to the deterioration of the lipid profile after AI treatment. Therefore, a customized individualization strategy considering each patient's CV risk factors is needed during AI treatment.

Impact of anti-oestrogen therapy on lipoprotein(a) in postmenopausal women: a systematic review and meta-analysis of double-blind placebo-controlled clinical studies

PURPOSE

The potential mechanisms of endocrine therapy for thrombosis remain currently unclear, and more studies are warranted for further investigation and elucidation. However, high plasma concentration of lipoprotein(a) (Lp(a)) is a recognized prothrombotic factor. The aim of our study was to systematically evaluate the effect of different anti-oestrogen therapy on plasma Lp(a) level in postmenopausal women.

METHODS

A systematic literature search was conducted in multiple electronic databases to identify the randomized, double-blind, placebo-controlled clinical studies on this topic. Effect size for changes in Lp(a) was expressed as mean difference (MD) and 95% confidence intervals (CI).

RESULTS

Data were pooled from 10 clinical trials comprising 24 treatment arms, which included 2049 women (1128 women in the active-treated arms and 921 women in the control arms). Meta-analysis of data suggested that anti-oestrogen therapy in women significantly reduced Lp(a) [MD = -5.92% (95%CI: -9.05%,-2.8%)].

CONCLUSIONS

This observation is of both clinical and pathophysiological relevance, also in view that the identification of molecular determinants and cellular pathways implicated in Lp(a) synthesis and metabolism is still of concern as a critical issue in lipidology and CV prevention.

Sex and Tamoxifen confound murine experimental studies in cardiovascular tissue engineering

Tissue engineered vascular grafts hold promise for the creation of functional blood vessels from biodegradable scaffolds. Because the precise mechanisms regulating this process are still under investigation, inducible genetic mouse models are an important and widely used research tool. However, here we describe the importance of challenging the baseline assumption that tamoxifen is inert when used as a small molecule inducer in the context of cardiovascular tissue engineering. Employing a standard inferior vena cava vascular interposition graft model in C57BL/6 mice, we discovered differences in the immunologic response between control and tamoxifen-treated animals, including occlusion rate, macrophage infiltration and phenotype, the extent of foreign body giant cell development, and collagen deposition. Further, differences were noted between untreated males and females. Our findings demonstrate that the host-response to materials commonly used in cardiovascular tissue engineering is sex-specific and critically impacted by exposure to tamoxifen, necessitating careful model selection and interpretation of results.

Impact of short-term low-dose tamoxifen on molecular breast imaging background parenchymal uptake: a pilot study

BACKGROUND

High background parenchymal uptake (BPU) on molecular breast imaging (MBI) has been identified as a breast cancer risk factor. We explored the feasibility of offering a short-term intervention of low-dose oral tamoxifen to women with high BPU and examined whether this intervention would reduce BPU.

METHODS

Women with a history of high BPU and no breast cancer history were invited to the study. Participants had an MBI exam, followed by 30 days of low-dose oral tamoxifen at either 5 mg or 10 mg/day, and a post-tamoxifen MBI exam. BPU on pre- and post-tamoxifen MBI exams was quantitatively assessed as the ratio of average counts in breast fibroglandular tissue vs. average counts in subcutaneous fat. Pre-tamoxifen and post-tamoxifen BPU were compared with paired t tests.

RESULTS

Of 47 women invited, 22 enrolled and 21 completed the study (10 taking 5 mg tamoxifen, 11 taking 10 mg tamoxifen). Mean age was 47.7 years (range 41-56 years). After 30 days low-dose tamoxifen, 8 of 21 women (38%) showed a decline in BPU, defined as a decrease from the pre-tamoxifen MBI of at least 15%; 11 of 21 (52%) had no change in BPU (within ± 15%); 2 of 21 (10%) had an increase in BPU of greater than 15%. Overall, the average post-tamoxifen BPU was not significantly different from pre-tamoxifen BPU (1.34 post vs. 1.43 pre, p = 0.11). However, among women taking 10 mg tamoxifen, 5 of 11 (45%) showed a decline in BPU; average BPU was 1.19 post-tamoxifen vs. 1.34 pre-tamoxifen (p = 0.005). In women taking 5 mg tamoxifen, 2 of 10 (20%) showed a decline in BPU; average BPU was 1.51 post-tamoxifen vs.1.53 pre-tamoxifen (p = 0.99).

CONCLUSIONS

Short-term intervention with low-dose tamoxifen may reduce high BPU on MBI for some patients. Our preliminary findings suggest that 10 mg tamoxifen per day may be more effective than 5 mg for inducing declines in BPU within 30 days. Given the variability in BPU response to tamoxifen observed among study participants, future study is warranted to determine if BPU response could predict the effectiveness of tamoxifen for breast cancer risk reduction within an individual.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02979301 . Registered 01 December 2016.

Suppression of Unspecific Enhancement on Breast Magnetic Resonance Imaging (Mri) by Antiestrogen Medication

Aims and Background

The value of breast MRI may be impaired by unspecific enhancement. This may leave patients with difficult-to-assess breast tissue with an uncertain diagnosis. We examined whether this unspecific enhancement (which is mostly due to proliferative or hyperplastic changes of benign breast tissue) may be suppressed by antiestrogen medication.

Methods

In a trial of treatment, 10 peri- or postmenopausal patients who exhibited diffuse and/or focal enhancement on breast MRI before tamoxifen medication agreed to undergo a short-term tamoxifen treatment. MRI monitoring was performed 2, 4 and 8 weeks after onset of antiestrogen therapy (tamoxifen, 30 mg per day).

Results

Six patients showed a significant decrease of enhancement. Unchanged (n = 3) or increased (n = 1) enhancement was seen in 4 patients. One of the three patients with unchanged enhancement proved to have diffuse lobular carcinoma in situ.

Conclusions

Part of the unspecific enhancement seen on breast MRI can probably be suppressed by short-term antiestrogen medication.

Cancer Prevention: Lessons Learned and Future Directions

In this review, we address selected areas that are central to the state-of-the-art of cancer prevention science. The emphasis on prevention as a viable and critical approach to decreasing cancer mortality has gained traction in recent years, evidenced by its inclusion in the US Vice President's Cancer Initiative (also termed 'Moonshot'). Cancer prevention occurs by arresting, slowing down, or reversing the carcinogenic process before invasion into surrounding tissue or by avoiding or blocking causative exposure. An important challenge is to identify individuals who will benefit most from preventive interventions with the least possible harm. Preventive interventions range from avoiding known carcinogens (e.g., tobacco or asbestos) to intervening with anticarcinogenic strategies (behavioral modifications , such as diet and exercise; medications; nutritional agents; and vaccination against causative agents). Here, we focus on active intervention with measures involving pharmaceutical and immunological agents.

The Effects of Tamoxifen on Plasma Lipoprotein(a) Concentrations: Systematic Review and Meta-Analysis

Introduction

Tamoxifen is a selective estrogen receptor modulator widely used in the treatment of breast cancer. Tamoxifen therapy is associated with lower circulating low-density lipoprotein cholesterol and increased triglycerides, but its effects on other lipids are less well studied.

Aims

We aimed to investigate the effect of tamoxifen on circulating concentrations of lipoprotein(a) [Lp(a)] through a meta-analysis of available randomized controlled trials (RCTs) and observational studies.

Methods

This study was registered in the PROSPERO database (CRD42016036890). Scopus, MEDLINE and EMBASE were searched from inception until 22 March 2016 to identify studies investigating the effect of tamoxifen on Lp(a) values in humans. Meta-analysis was performed using an inverse variance-weighted, random-effects model with standardized mean difference (SMD) as the effect size estimate.

Results

Meta-analysis of five studies with 215 participants suggested a statistically significant reduction of Lp(a) levels following tamoxifen treatment (SMD −0.41, 95% confidence interval −0.68 to −0.14, p = 0.003). This effect was robust in the sensitivity analysis.

Conclusions

Meta-analysis suggested a statistically significant reduction of Lp(a) levels following tamoxifen treatment. Further well-designed trials are required to validate these results.

How do we increase uptake of tamoxifen and other anti-estrogens for breast cancer prevention?

Several randomized controlled trials of anti-estrogens, such as tamoxifen and aromatase inhibitors, have demonstrated up to a 50–65% decrease in breast cancerincidence among high-risk women. Approximately 15% of women, age 35–79 years, in the U.S. meet criteria for breast cancer preventive therapies, but uptake of these medications remain low. Explanations for this low uptake includelack of awareness of breast cancer risk status, insufficient knowledge about breast cancer preventive therapies among patients and physicians, and toxicity concerns. Increasing acceptance of pharmacologic breast cancer prevention will require effective communication of breast cancer risk, accurate representation about the potential benefits and side effects of anti-estrogens, targeting-specific high-risk populations most likely to benefit from preventive therapy, and minimizing the side effects of current anti-estrogens with novel administration and dosing options. One strategy to improve the uptake of chemoprevention strategies is to consider lessons learned from the use of drugs to prevent other chronic conditions, such as cardiovascular disease. Enhancing uptake and adherence to anti-estrogens for primary prevention holds promise for significantly reducing breast cancer incidence, however, this will require a significant change in our current clinical practice and stronger advocacy and awareness at the national level.

Estrogens and selective estrogen receptor modulators in acromegaly

Despite recent advances in acromegaly treatment by surgery, drugs, and radiotherapy, hormonal control is still not achieved by some patients. The impairment of IGF-1 generation by estrogens in growth hormone deficient patients is well known. Patients on oral estrogens need higher growth hormone doses in order to achieve normal IGF-1 values. In the past, estrogens were one of the first drugs used to treat acromegaly. Nevertheless, due to the high doses used and the obvious side effects in male patients, this strategy was sidelined with the development of more specific drugs, as somatostatin receptor ligands and dopamine agonists. In the last 15 years, the antagonist of growth hormone receptor became available, making possible IGF-1 control of the majority of patients on this particular drug. However, due to its high cost, pegvisomant is still not available in many centers around the world. In this setting, the effect of estrogens and also of selective estrogen receptor modulators on IGF-1 control was reviewed, and proved to be an ancillary tool in the management of acromegaly. This review describes data concerning their efficacy and place in the treatment algorithm of acromegaly.

Addressing barriers to uptake of breast cancer chemoprevention for patients and providers

Breast cancer is the most common malignancy among women in the United States, and the primary prevention of this disease is a major public health issue. Because there are relatively few modifiable breast cancer risk factors, pharmacologic interventions with antiestrogens have the potential to significantly affect the primary prevention setting. Breast cancer chemoprevention with selective estrogen receptor modulators (SERMs) tamoxifen and raloxifene, and with aromatase inhibitors (AIs) exemestane and anastrozole, is underutilized despite several randomized controlled trials demonstrating up to a 50% to 65% relative risk reduction in breast cancer incidence among women at high risk. An estimated 10 million women in the United States meet high-risk criteria for breast cancer and are potentially eligible for chemoprevention, but less than 5% of women at high risk who are offered antiestrogens for primary prevention agree to take it. Reasons for low chemoprevention uptake include lack of routine breast cancer risk assessment in primary care, inadequate time for counseling, insufficient knowledge about antiestrogens among patients and providers, and concerns about side effects. Interventions designed to increase chemoprevention uptake, such as decision aids and incorporating breast cancer risk assessment into clinical practice, have met with limited success. Clinicians can help women make informed decisions about chemoprevention by effectively communicating breast cancer risk and enhancing knowledge about the risks and benefits of antiestrogens. Widespread adoption of chemoprevention will require a major paradigm shift in clinical practice for primary care providers (PCPs). However, enhancing uptake and adherence to breast cancer chemoprevention holds promise for reducing the public health burden of this disease.

Barriers to preventive therapy for breast and other major cancers and strategies to improve uptake

The global cancer burden continues to rise and the war on cancer can only be won if improvements in treatment go hand in hand with therapeutic cancer prevention. Despite the availability of several efficacious agents, utilisation of preventive therapy has been poor due to various barriers, such as the lack of physician and patient awareness, fear of side effects, and licensing and indemnity issues. In this review, we discuss these barriers in detail and propose strategies to overcome them. These strategies include improving physician awareness and countering prejudices by highlighting the important differences between preventive therapy and cancer treatment. The importance of the agent-biomarker-cohort (ABC) paradigm to improve effectiveness of preventive therapy cannot be overemphasised. Future research to improve therapeutic cancer prevention needs to include improvements in the prediction of benefits and harms, and improvements in the safety profile of existing agents by experimentation with dose. We also highlight the role of drug repurposing for providing new agents as well as to address the current imbalance between therapeutic and preventive research. In order to move the field of therapeutic cancer prevention forwards, engagement with policymakers to correct research imbalance as well as to remove practical obstacles to implementation is also urgently needed.

Alternate dosing schedules for cancer chemopreventive agents

Pharmacologic interventions for cancer risk reduction involve the chronic administration of synthetic or natural agents to reduce or delay the occurrence of malignancy. Despite the strong evidence for a favorable risk-benefit ratio for a number of agents in several common malignancies such as breast and prostate cancer, the public's attitude toward cancer chemoprevention remains ambivalent, with the issue of toxicity associated with drugs being perceived as the main barrier to widespread use of preventive therapy by high-risk subjects. Among the strategies to overcome such obstacles to preventive therapies, two novel and potentially safer modes of administering agents are discussed in this paper. The first strategy is to lower the dose of drugs that are in common use in the adjuvant setting based on the notion that prevention of cancer cells from developing should require a lower dose than eradicating established tumor cells. A second approach is to adopt an intermittent administration similar to what is used in the chemotherapy setting in an attempt to minimize risks while retaining benefits. This article provides a detailed discussion of the principles and future development of these two approaches in the direction of a precision preventive medicine.

Tamoxifen for women at high risk of breast cancer

Tamoxifen has been used as a treatment for women who have been diagnosed with breast cancer for roughly four decades and has been approved as chemoprevention for over ten years. Although tamoxifen has been proven to be beneficial in preventing breast cancer in high-risk women, its use has not been widely embraced. To some extent, this is due to several of its side effects, including an increased risk of endometrial cancer and pulmonary embolism, but these serious side effects are rare. The risks and benefits of tamoxifen chemoprevention should be considered for each patient.

Effects of adjuvant aromatase inhibitor therapy on lipid profiles

How aromatase inhibitors affect lipids is of great interest. Compared with tamoxifen, adjuvant anastrozole and letrozole are associated with increased incidences of hypercholesterolemia, while similar data are lacking for exemestane in the adjuvant setting. No significant differences in lipid profiles occurred with extended adjuvant exemestane compared with placebo, but total cholesterol and low-density lipoprotein levels increased significantly above baseline in both groups over 6 months. Likewise, no significant differences in hypercholesterolemia rates occurred between extended adjuvant letrozole and placebo. A lipid substudy further confirmed that letrozole did not significantly alter serum lipids for 36 months compared with placebo. Thus, although aromatase inhibitors lack the lipid-lowering properties of tamoxifen, no significant worsening of lipid levels occurs with their use. Patients would benefit from lifestyle changes and routine monitoring of serum lipids. Breast cancer therapy trials often report serum lipid parameters, but assessing the quality and overall significance of the data can be difficult. Methodology of data collection varies among trials and the concomitant use of lipid-modifying medication is often not reported. This review discusses the current understanding of the influence of lipid levels on cardiovascular risk in women and presents key findings on the effects of adjuvant aromatase inhibitor therapy on lipid profiles.

Effect of low-dose tamoxifen after surgical excision of ductal intraepithelial neoplasia: results of a large retrospective monoinstitutional cohort study

BACKGROUND

Postsurgical treatment of ductal intraepithelial neoplasia (DIN) with standard doses of tamoxifen has not reached a consensus yet. Given positive results of low-dose tamoxifen on breast cancer biomarkers modulation, we analyzed a large cohort of DIN patients treated with low-dose tamoxifen or no treatment as per institutional guidelines.

PATIENTS AND METHODS

All consecutive women operated on at the European Institute of Oncology for estrogen receptor (ER)-positive DIN (474 treated with low-dose tamoxifen and 509 untreated patients) were followed up for a median of 7 years.

RESULTS

Compared with untreated patients, a significant 30% reduction in breast cancer risk was observed on low-dose tamoxifen with an adjusted hazard ratio (HR) = 0.70 [95% confidence interval (CI) 0.51-0.94], with a greater benefit in postmenopausal (HR = 0.57; 95% CI 0.34-0.94) than in premenopausal women (HR = 0.79; 95% CI 0.54-1.17). Treated patients with ER and progesterone receptor (PgR) >50% DIN had a lower incidence of breast events than untreated ones (HR = 0.61; 95% CI 0.40-0.94), whereas no protective effect has been observed in patients with ER or PgR <50% DIN. Drug discontinuation resulted in a doubled risk of recurrence in premenopausal women only (HR = 1.95; 95% CI 0.98-3.89). No excess of endometrial cancer occurred.

CONCLUSIONS

Low-dose tamoxifen is a promising and safe strategy for highly endocrine responsive DIN. Treatment adherence is crucial in premenopausal women. A definitive trial is ongoing.

TARGETING THE GENOTOXIC EFFECTS OF ESTROGENS

Our studies indicate that expression of antioxidative stress enzymes is upregulated by Selective Estrogen Receptor Modulators (SERMs) in breast epithelial cell lines, providing protection against the genotoxic effects of estrogens and against estrogen-induced mammary tumorigenesis. This upregulation of antioxidative stress enzymes requires Estrogen Receptor beta (ERβ) and human homolog of Xenopus gene which Prevents Mitotic Catastrophe (hPMC2). Further studies indicate that hPMC2 has a functional exonuclease domain that is required for upregulation of antioxidative stress enzymes by SERMs and repair of estrogen-induced abasic sites.

Oral low dose and topical tamoxifen for breast cancer prevention: modern approaches for an old drug

Tamoxifen is a drug that has been in worldwide use for the treatment of estrogen receptor (ER)-positive breast cancer for over 30 years; it has been used in both the metastatic and adjuvant settings. Tamoxifen's approval for breast cancer risk reduction dates back to 1998, after results from the Breast Cancer Prevention Trial, co-sponsored by the National Cancer Institute and the National Surgical Adjuvant Breast and Bowel Project, showed a 49% reduction in the incidence of invasive, ER-positive breast cancer in high-risk women. Despite these positive findings, however, the public's attitude toward breast cancer chemoprevention remains ambivalent, and the toxicities associated with tamoxifen, particularly endometrial cancer and thromboembolic events, have hampered the drug's uptake by high-risk women who should benefit from its preventive effects. Among the strategies to overcome such obstacles to preventive tamoxifen, two novel and potentially safer modes of delivery of this agent are discussed in this paper. Low-dose tamoxifen, expected to confer fewer adverse events, is being investigated in both clinical biomarker-based trials and observational studies. A series of systemic biomarkers (including lipid and insulin-like growth factor levels) and tissue biomarkers (including Ki-67) are known to be favorably affected by conventional tamoxifen dosing and have been shown to be modulated in a direction consistent with a putative anti-cancer effect. These findings suggest possible beneficial clinical preventive effects by low-dose tamoxifen regimens and they are supported by observational studies. An alternative approach is topical administration of active tamoxifen metabolites directly onto the breast, the site where the cancer is to be prevented. Avoidance of systemic administration is expected to reduce the distribution of drug to tissues susceptible to tamoxifen-induced toxicity. Clinical trials of topical tamoxifen with biological endpoints are still ongoing whereas pharmacokinetic studies have already shown that appropriate formulations of drug successfully penetrate the skin to reach breast tissue, where a preventive effect is sought.

Breast cancer chemoprevention: old and new approaches

In 1976, Sporn has defined chemoprevention as “the use of pharmacologic or natural agents that inhibit the development of invasive breast cancer either by blocking the DNA damage that initiates carcinogenesis, or by arresting or reversing the progression of premalignant cells in which such damage has already occurred.” Although the precise mechanism or mechanisms that promote a breast cancer are not completely established, the success of several recent clinical trials in preventive settings in selected high-risk populations suggests that chemoprevention is a rational and an appealing strategy. Breast cancer chemoprevention has focused heavily on endocrine intervention using selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs). Achieving much success in this particular setting and new approaches as low-dose administration are actually under investigations in several topics. Unfortunately, these drugs are active in prevention of endocrine responsive lesions only and have no effect in reducing the risk of estrogen-negative breast cancer. Thus, recently new pathways, biomarkers, and agents likely are to be effective in this subgroup of cancers and were put under investigation. Moreover, the identification of new potential molecular targets and the development of agents aimed at these targets within cancer have already had a significant impact on advanced cancer therapy and provide a wealth of opportunities for chemoprevention. This paper will highlight current clinical research in both ER-positive and ER-negative breast cancer chemoprevention, explaining the biologic effect of the various agents on carcinogenesis and precancerous lesions, and finally presenting an excursus on the state-of-the-art about new molecular targets under investigations in breast cancer settings.

Effects of tomato- and soy-rich diets on the IGF-I hormonal network: a crossover study of postmenopausal women at high risk for breast cancer

To determine whether dietary modifications with tomato products and/or a soy supplement affected circulating levels of insulin-like growth factor (IGF)-1 and other markers of cell signaling in postmenopausal women at risk for developing breast cancer. Eligible and consented postmenopausal women at high risk for developing breast cancer were enrolled in a 26-week, two-arm (tomato and soy, 10 weeks each) longitudinal dietary intervention study in which each woman served as her own control. Changes in biochemical endpoints including IGF-I, IGF-binding protein (IGFBP)-3, estradiol, sex hormone-binding globulin (SHBG), C-peptide, and insulin were measured for each intervention arm. Carotenoid and isoflavone levels were measured to assess adherence. Significant increases in carotenoid and isoflavone levels during the tomato and soy study arms, respectively, suggested that women were adherent to both arms of the intervention. The tomato-rich diet had little effect on cell-signaling biomarkers previously associated with breast cancer risk. However, results of the soy intervention showed that concentrations of IGF-I and IGFBP-3 increased by 21.6 and 154.7 μmol/L, respectively (P = 0.001 for both) and SHBG decreased by 5.4 μmol/L (P < 0.001) after consumption of the soy protein supplement. Increased soy protein intake may lead to small, but significant, increases in IGF-I and IGFBP-3. Soy consumption also led to a significant decrease in SHBG, which has been hypothesized to promote, rather than prevent, cancer growth. Previous epidemiologic studies, however, have confirmed protective effect of soy on breast cancer. Additional investigation about the effect of soy on breast cancer risk and its mechanism of action is warranted.

Aromatase inhibitor-induced loss of grip strength is body mass index dependent: hypothesis-generating findings for its pathogenesis

BACKGROUND

Our preliminary results showed that tenosynovial changes and decrease in grip strength are associated with the aromatase inhibitor-induced musculoskeletal syndrome (AIMSS). Here, we report the final results and assess the relationship between grip strength and body mass index (BMI).

PATIENTS AND METHODS

We conducted a prospective study including postmenopausal early breast cancer patients receiving either an aromatase inhibitor (AI) or tamoxifen. Primary end point was change from baseline in tenosynovial abnormalities. Secondary end points were changes from baseline in morning stiffness, intra-articular fluid and grip strength and its association with BMI.

RESULTS

After 6 months of therapy, 74% [95% confidence interval (CI) 51% to 89%] of AI-treated patients had worsened tenosynovial abnormalities, 56% (95% CI 34% to 75%) had increased intra-articular fluid, and 22% (95% CI 9% to 45%) had increased morning stiffness. Grip strength decreased 8% for the left hand (95% CI 2% to 21%) and 11% for the right (95% CI 4% to 17%). Regression analysis suggested that grip strength decreased more for subjects with high or with low BMI.

CONCLUSIONS

AIMSS is characterized by tenosynovial changes, intra-articular fluid and morning stiffness. We hypothesize that the quadratic association between BMI and loss of grip strength reflects AI-induced changes on the endocrine control of the growth hormone insulin-like growth factor-I pathway.

Breast cancer recurrence risk related to concurrent use of SSRI antidepressants and tamoxifen

BACKGROUND

Up to one-quarter of breast cancer patients suffer clinically significant depression in the year after diagnosis, which may respond to intervention. About half may be prescribed a psychotropic medication, such as a selective serotonin reuptake inhibitor (SSRI), while completing breast cancer therapy. Cytochrome P-450 2D6 (CYP2D6) metabolizes SSRIs and also metabolizes tamoxifen to more active forms. Therefore, concurrent use of SSRIs may reduce tamoxifen's effectiveness at preventing breast cancer recurrence. The SSRI citalopram has limited potency to inhibit CYP2D6 activity, so has been recommended for breast cancer patients taking tamoxifen. This study provides epidemiologic evidence to support this recommendation.

MATERIAL AND METHODS

We conducted a case-control study of breast cancer recurrence nested in the population of female residents of Denmark who were diagnosed with non-metastatic estrogen-receptor positive breast cancers between 1994 and 2001 and who took tamoxifen for at least one year. We ascertained complete prescription histories by linking cases' and controls' civil registration numbers to the Danish national prescription registry. We estimated the association between SSRI use while taking tamoxifen and risk of recurrent breast cancer.

RESULTS

About the same proportion of recurrent cases (37 of 366) and matched controls (35 of 366) received at least one prescription for citalopram or its s-stereoisomer while taking tamoxifen (adjusted odds ratio = 1.1, 95% confidence interval = 0.7, 1.7). Breast cancer patients taking other SSRIs were also at no increased risk of recurrence (adjusted odds ratio = 0.9, 95% confidence interval = 0.5, 1.8).

DISCUSSION

Breast cancer patients with indications for an SSRI may be prescribed citalopram - and possibly other SSRI - without adversely affecting the outcome of adjuvant therapy with tamoxifen.

Randomized double-blind 2 x 2 trial of low-dose tamoxifen and fenretinide for breast cancer prevention in high-risk premenopausal women

PURPOSE

Tamoxifen and fenretinide are active in reducing premenopausal breast cancer risk and work synergistically in preclinical models. The authors assessed their combination in a two-by-two biomarker trial.

PATIENTS AND METHODS

A total of 235 premenopausal women with pT1mic/pT1a breast cancer (n = 21), or intraepithelial neoplasia (IEN, n = 160), or 5-year Gail risk > or = 1.3% (n = 54) were randomly allocated to either tamoxifen 5 mg/d, fenretinide 200 mg/d, their combination, or placebo. We report data for plasma insulin-like growth factor I (IGF-I), mammographic density, uterine effects, and breast neoplastic events after 5.5 years.

RESULTS

During the 2-year intervention, tamoxifen significantly lowered IGF-I and mammographic density by 12% and 20%, respectively, fenretinide by 4% and 10% (not significantly), their combination by 20% and 22%, with no evidence for a synergistic interaction. Tamoxifen increased endometrial thickness principally in women becoming postmenopausal, whereas fenretinide decreased endometrial thickness significantly. The annual rate of breast neoplasms (n = 48) was 3.5% +/- 1.0%, 2.1% +/- 0.8%, 4.7% +/- 1.3%, and 5.2% +/- 1.3% in the tamoxifen, fenretinide, combination, and placebo arms, respectively, with hazard ratios (HRs) of 0.70 (95% CI, 0.32 to 1.52), 0.38 (95% CI, 0.15 to 0.90), and 0.96 (95% CI, 0.46 to 1.99) relative to placebo (tamoxifen x fenretinide adverse interaction P = .03). There was no clear association with tumor receptor type. Baseline IGF-I and mammographic density did not predict breast neoplastic events, nor did change in mammographic density.

CONCLUSION

Despite favorable effects on plasma IGF-I levels and mammographic density, the combination of low-dose tamoxifen plus fenretinide did not reduce breast neoplastic events compared to placebo, whereas both single agents, particularly fenretinide, showed numerical reduction in annual odds of breast neoplasms. Further follow-up is indicated.

Menopausal symptoms in women treated for breast cancer: the prevalence and severity of symptoms and their perceived effects on quality of life

OBJECTIVES

To determine, first, the prevalence and severity of various symptoms related to estrogen deficiency in women within a few years of receiving treatment for breast cancer, second, how women perceive the effects of these symptoms on their quality of life and, third, what measures have been taken to relieve vasomotor symptoms.

METHODS

Two hundred women (aged 29-65 years) who had received treatment for breast cancer within the last 5 years were included in this cross-sectional survey. Information was collected about their breast cancer treatment, menopausal symptoms (Menopausal Rating Scale), the perceived effects of menopausal symptoms on their and their partner's quality of life and any treatments they were receiving for hot flushes.

RESULTS

All but one woman reported at least one symptom related to the menopause (95.9% vasomotor; 83.3% psychological; 89.7% somatic). Current treatment with tamoxifen or previous chemotherapy did not influence the prevalence or the severity of hot flushes. Current antidepressant treatment was, however, significantly associated with a higher prevalence and severity of most menopausal symptoms, including hot flushes and sweats (p = 0.008). The severity of hot flushes and sweats was significantly correlated with self-assessed effects on overall quality of life (r(s) = 0.47); 56.4% of the respondents believed that menopausal symptoms had affected their partner's quality of life, the strongest correlations being with severity of sexual symptoms (r(s) = 0.56) and vaginal dryness (r(s) = 0.5). Only 21% of women experiencing hot flushes were receiving any treatment for hot flushes, with most women describing no knowledge or poor knowledge of treatment options.

CONCLUSIONS

The majority of women receiving treatment for breast cancer report menopausal symptoms, which negatively correlate, not only with their own, but also with their partner's quality of life. Most women experiencing hot flushes are not receiving treatment due to lack of both awareness and confidence in the existing treatment options.

Tamoxifen's protection against breast cancer recurrence is not reduced by concurrent use of the SSRI citalopram

Tamoxifen remains an important adjuvant therapy to reduce the rate of breast cancer recurrence among patients with oestrogen-receptor-positive tumours. Cytochrome P-450 2D6 metabolizes tamoxifen to metabolites that more readily bind the oestrogen receptor. This enzyme also metabolizes selective serotonin reuptake inhibitors (SSRI), so these widely used drugs - when taken concurrently - may reduce tamoxifen's prevention of breast cancer recurrence. We studied citalopram use in 184 cases of breast cancer recurrence and 184 matched controls without recurrence after equivalent follow-up. Cases and controls were nested in a population of female residents of Northern Denmark with stages I-III oestrogen-receptor-positive breast cancer 1985-2001 and who took tamoxifen for 1, 2, or most often for 5 years. We ascertained prescription histories by linking participants' central personal registry numbers to prescription databases from the National Health Service. Seventeen cases (9%) and 21 controls (11%) received at least one prescription for the SSRI citalopram while taking tamoxifen (adjusted conditional odds ratio=0.85, 95% confidence interval=0.42, 1.7). We also observed no reduction of tamoxifen effectiveness among regular citalopram users (>or=30% overlap with tamoxifen use). These results suggest that concurrent use of citalopram does not reduce tamoxifen's prevention of breast cancer recurrence.

Randomized Dose-Ranging Trial of Tamoxifen at Low Doses in Hormone Replacement Therapy Users

Purpose

The combination of hormone replacement therapy (HRT) and low-dose tamoxifen may retain the benefits while reducing the risks of either agent. We assessed the optimal biologic dose and schedule of tamoxifen in HRT users using surrogate end point biomarkers and menopausal symptoms.

Subjects and Methods

Two hundred ten current or de novo HRT users were randomly assigned to one of the following four arms: tamoxifen 1 mg/day and placebo/week, placebo/day and tamoxifen 10 mg/week, tamoxifen 5 mg/day and placebo/week, or both placebos for 12 months. The primary end point was the change of plasma insulinlike growth factor 1 (IGF-I) through 12 months, and secondary end points were IGF-I/IGF binding protein-3 (IGFBP-3) ratio, fibrinogen, antithrombin III, C reactive protein, C-telopeptide, mammographic percent density, and endometrial thickness. Endometrial proliferation was assessed by Pipelle biopsy in superficial, deep glandular, and stromal compartments after 12 months.

Results

Compared with placebo, IGF-I declined in all tamoxifen arms (P = .005), with a greater change on 5 mg/day (P = .019 v 10 mg/week or 1 mg/day). Tamoxifen increased IGFBP-3 and lowered antithrombin-III, C reactive protein, and mammographic density, with greater effects of 5 mg/day. Tamoxifen increased endometrial thickness but not Ki-67 expression, which was lower on 5 mg/day among the three doses. Menopausal symptoms were not significantly worsened by tamoxifen.

Conclusion

Doses of tamoxifen ≤ 5 mg/day modulate favorably biomarkers of breast carcinogenesis and cardiovascular risk in HRT users with no increase of endometrial proliferation and menopausal symptoms. A dose of 5 mg/day was the most effective and has been selected for a phase III trial in HRT users.

Concentration Dependent Different Action of Tamoxifen on Membrane Fluidity

Tamoxifen (TAM) is a non-steroidal antiestrogen drug, which is widely used to prevent and treat breast, liver, pancreas and brain cancers. The present work investigates, in detail, the concentration dependent behavior of TAM (varying from 1 mol% to 45 mol%) on membrane fluidity. The differential scanning calorimetry (DSC) studies showed that tamoxifen eliminates the pre-transition and decreases the main phase transition to lower temperatures. Using visible spectroscopy at 440 nm and Fourier transform infrared (FTIR) spectroscopy it was found that membrane dynamics decreases for 1 and 3 mol% tamoxifen in both the gel and liquid crystalline phases. Above these concentrations up to 18–24 mol%, it increases and reaches its maximum values. As tamoxifen concentration was further increased, the membrane dynamics is found to be gradually decreased, although TAM still has fluidifying effect in comparison to pure phospholipid membrane. These findings are important for the effective use of tamoxifen in the cancer therapy to eliminate its dose dependent side effects reported in the literature.

Regulation of growth hormone signaling by selective estrogen receptor modulators occurs through suppression of protein tyrosine phosphatases

Activation of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 5 (STAT5) pathway by GH is terminated by the suppressors of cytokine signaling (SOCSs) and protein tyrosine phosphatases, Src homology 2 domain-containing protein tyrosine phosphatase (SHP)-1 and SHP-2. Based on our recent report that estrogen inhibits GH signaling by stimulating SOCS-2 expression, we investigated the effects of selective estrogen receptor modulators (SERMs) on GH signaling in human embryonic kidney (HEK293) and breast cancer (MDA-MB-231) cells expressing human GH receptor and estrogen receptor-alpha. 17beta-estradiol (E(2)) suppressed GH activation of a STAT5-responsive luciferase reporter and JAK2 phosphorylation in both cell models. 4-hydroxytamoxifen and raloxifene augmented these actions of GH in HEK293 cells but not breast cancer cells. SOCS-2 expression in both cell types was stimulated by E(2) but unaffected by SERMs. In HEK293 cells, SHP-1 was inhibited by raloxifene and 4-hydroxytamoxifen, whereas the latter additionally inhibited SHP-2. The phosphatases were unaffected by E(2). In breast cancer cells, phosphatase activity was not altered by SERMs or E(2). In summary, estrogen inhibited the JAK2/STAT5 signaling of GH and stimulated SOCS-2 expression in both HEK293 and breast cancer cells. By contrast, SERMs augmented GH signaling by reducing SHP activities in HEK293 cells and had no effect on both in breast cancer cells. We provide the first evidence for a novel mechanism regulating GH signaling, in which SERMs enhance GH activation of the JAK2/STAT5 pathway in a cell-type-dependent manner by attenuating protein tyrosine phosphatase activities.

Isolated isoflavones do not affect the circulating insulin-like growth factor system in men at increased colorectal cancer risk

Epidemiological studies show that increased insulin-like growth factor (IGF)-I concentrations are related to increased colorectal cancer risk. A reduced colorectal cancer risk has been associated with isoflavones, which might affect the IGF-system because of their weak estrogenic activity. We conducted a randomized, placebo-controlled, double-blind crossover study to investigate the effect of an 8-wk isolated isoflavone supplementation (84 mg/d) on serum concentrations of total IGF-I, free IGF-I, total IGF-II, IGF binding protein (BP)-1, IGFBP-2, and IGFBP-3. Additionally, we investigated whether IGF-system component differences were related to concentrations of the more potent estrogenic isoflavone metabolite, equol. Our study population consisted of 37 men with a family history of colorectal cancer or a personal history of colorectal adenomas. Isoflavone supplementation did not significantly affect serum total IGF-I concentrations (relative difference between serum total IGF-I concentrations after isoflavone supplementation and after placebo: -1.3%, 95% CI -8.6 to 6.0%). Neither free IGF-I, nor total IGF-II, IGFBP-1, IGFBP-2, or IGFBP-3 concentrations were significantly altered. Interestingly, the change in serum IGF-I concentrations after isoflavone supplementation was negatively associated with serum equol concentrations (r=-0.49, P=0.002). In conclusion, isolated isoflavones did not affect the circulating IGF-system in a male high-risk population for colorectal cancer. However, to our knowledge, this is the first study that suggests isoflavones might have an IGF-I lowering effect in equol producers only. This underlines the importance of taking into account equol status in future isoflavone intervention studies.

The differential effects of bisphosphonates, SERMS (selective estrogen receptor modulators), and parathyroid hormone on bone remodeling in osteoporosis

Osteoporosis is a skeletal metabolic disease characterized by a compromised bone fragility, leading to an increased risk of developing spontaneous and traumatic fractures. Osteoporosis is considered a multifactorial disease and fractures are the results of several different risk factors both extra- and intraskeletal. Thus bone fragility can be the end point of several different causes: a) failure to reach an optimal peak bone mass during growth; b) excessive bone resorption resulting in decreased bone mass and microarchitectural deterioration; c) inadequate formation upon an increased resorption during the process of bone remodeling. The pharmacological therapeutical options, available to date, are directed on prevention of fractures. The aim of this paper is to describe the activities and the mechanisms of action, as known at present, of the most used therapies for osteoporosis and their clinical implications. Improvement of knowledge in this field will allow us to further improve therapeutical choices and pharmacological interventions.

Chemoprevention of breast cancer: tamoxifen, raloxifene, and beyond

Breast cancer is the most common cancer and the second most common cause of cancer death among women in the United States. While nonrandomized studies have reported that prophylactic mastectomy or oophorectomy can significantly reduce the risk of breast cancer, these approaches are unacceptable to the majority of women. Chemoprevention, which is defined as the prevention of cancer by pharmacological agents that inhibit or reverse the process of carcinogenesis, has thus increasingly become the focus of breast cancer prevention efforts. The first-generation selective estrogen receptor modulator (SERM) tamoxifen is the only US Food and Drug Administration- approved drug for breast cancer prevention and reduces the risk of breast cancer by as much as 50% in high-risk women. Raloxifene, a second-generation SERM, also has demonstrated efficacy for breast cancer prevention and is being compared with tamoxifen in a large randomized trial that has recently completed accrual. The aromatase inhibitors (AIs) decrease the incidence of contralateral breast cancer when used in the adjuvant setting and are being evaluated in ongoing primary prevention studies. In addition, a number of novel agents, including antiinflammatory drugs and retinoid derivatives, which appear to be of promise based on preclinical and epidemiological data, are under investigation. Several important challenges remain, including determination of the appropriate dose and duration of treatment when used in the primary prevention setting and development of new research models using surrogate end points for breast cancer incidence and mortality to permit more rapid clinical application of promising new agents.

Serum Insulin-Like Growth Factor-I Levels Among Women in Hawaii and Japan With Different Levels of Tofu Intake

Insulin-like growth factor-I (IGF-I) has been proposed as the link between diet and breast cancer risk. Due to their estrogen-like structure, soy isoflavones may affect IGF-I levels in a similar way as exogenous estrogens. In a cross-sectional design, we compared IGF-I levels between women with high and low soy intake. The analysis included 611 pre- and postmenopausal women: Japanese in Japan and Japanese and Caucasians in Hawaii. The subjects had participated in a previous study, were never diagnosed with breast cancer, provided a screening mammogram and a blood sample, and completed validated food-frequency questionnaires. The same laboratory analyzed all serum samples for IGF-I and IGF binding protein (IGFBP)-3 by enzyme-linked immunosorbent assay. We estimated covariate-adjusted mean IGF-I and IGFBP-3 levels by tofu intake. The respective mean IGF-I levels were 213, 257, and 255 ng/ml for Japanese in Japan, Japanese in Hawaii, and Caucasians in Hawaii. Tofu intake was higher in Japan than among Japanese and Caucasians in Hawaii (11.0 vs. 9.4 and 4.9 g/1,000 kcal). Mean IGF-I levels were 11% lower among women in the highest tofu intake category compared with the lowest, but the difference in IGF-I levels between the highest and lowest tofu category was only significant among women in Japan. Inclusion of total energy, total protein, meat, and dairy intake did not materially alter the association between tofu consumption and IGF-I levels. These findings suggest that a diet rich in soy foods and low in meats may be related to lower IGF-I levels, but it is unclear whether soy or other characteristics of diet and lifestyle are responsible for this association.

Effects of low-dose tamoxifen on breast cancer biomarkers Ki-67, estrogen and progesterone receptors

Breast carcinoma is the most common malignancy among women and it has a major impact on mortality. Studies of primary chemoprevention with tamoxifen have generated high expectations and considerable success rates. The efficacy of lower doses of tamoxifen is similar to that seen with a standard dose of the drug, and there has been a reduction in healthcare costs and side effects.

The immune reaction to monoclonal antibody Ki-67 (MIB-1) and the expression of estrogen receptors (1D5) and progesterone receptors (PgR 636) in breast carcinoma were studied in patients treated with 10 mg of tamoxifen for a period of 14 days.

A prospective randomized clinical trial was conducted with 38 patients divided into two groups: Group A: N = 20 (control group-without medication) and Group B: N = 18 (tamoxifen/10 mg/day for 14 days). All patients signed an informed consent term previously approved by both institutions. Patients underwent incisional biopsy before treatment and 14 days later a tumor tissue sample was obtained during surgical treatment. Positivity was quantitatively assessed, counting at least 1.000 cells per slide. For statistical data analysis, a Wilcoxon non-parametric test was used, and α was set at 5%.

Both groups (A and B) were considered homogeneous regarding control variables. In Group A (control), there was no statistically significant reduction in Ki-67 (MIB-1) (p = 0.627), estrogen receptor (1D5) (p = 0.296) and progesterone receptor positivity (PgR 636) (p = 0.381).

In Group B (tamoxifen 10 mg/day), the mean percentage of nuclei stained by Ki-67 (MIB-1) was 24.69% before and 10.43% after tamoxifen treatment. Mean percentage of nuclei stained by estrogen receptor (1D5) was 59.53% before and 25.99% after tamoxifen treatment. Mean percentage of nuclei stained by progesterone receptor (PgR 636), was 59.34 before and 29.59% after tamoxifen treatment. A statistically significant reduction was found with the three markers (p < 0.001).

Tamoxifen significantly reduced monoclonal antibody Ki-67 (MIB-1), estrogen receptor (1D5) and progesterone receptor positivity (PgR 636) in the breast epithelium of carcinoma patients treated with a 10 mg dose of tamoxifen for 14 days.

Adjuvant Hormonal Therapy in Peri‐ and Postmenopausal Breast Cancer

Tamoxifen has been the mainstay of endocrine treatment for early-stage breast cancer in both premenopausal and postmenopausal women for many years. Since 2001, the results of several large, randomized, clinical trials have provided evidence that aromatase inhibitor (AI) therapy, either upfront or in sequence after tamoxifen, improves disease-free survival and, in certain patients, overall survival for postmenopausal patients with hormone receptor-positive breast cancer. Thus far, with relatively short-term follow-up, AIs have been generally safe and well tolerated among the population of patients treated in these adjuvant trials. However, important side effects such as musculoskeletal and bone-related problems, including the risk for osteoporosis and fractures, remain of concern and warrant continued monitoring and follow-up. Several questions regarding the appropriate AI to use and the timing of AI therapy remain unresolved, and ongoing studies will help address these issues. Caution is warranted in the use of AIs in perimenopausal women, including those that develop chemotherapy-induced amenorrhea, and clinical evidence supports the role for AI use in postmenopausal women only. Areas of active investigation include the mechanisms of resistance to endocrine therapy with tamoxifen and AIs and clinical strategies to overcome this resistance.

Preliminary results on safety and activity of a randomized, double-blind, 2 x 2 trial of low-dose tamoxifen and fenretinide for breast cancer prevention in premenopausal women

PURPOSE

To determine whether low-dose tamoxifen and fenretinide have a synergistic effect on surrogate biomarkers, including circulating insulin-like growth factor I (IGF-I) and mammographic density, in premenopausal women at risk for breast cancer and to study drug safety.

PATIENTS AND METHODS

Premenopausal women (n = 235) were randomly assigned in a double-blind four-arm trial to receive tamoxifen 5 mg/d, fenretinide 200 mg/d, both agents, or placebo for 2 years. The present analysis refers to preliminary data on safety, IGF-I, and breast cancer events.

RESULTS

Patients were included if they had an excised ductal carcinoma-in-situ (57%), lobular carcinoma-in-situ (13%), minimal invasive breast cancer (7%), or a 5-year Gail risk > or = 1.3% (23%). After a median follow-up of 40 months, there was a reduction of 13%, 2%, 20%, and 1% in IGF-I levels for patients on tamoxifen, fenretinide, tamoxifen plus fenretinide, and placebo, respectively. Recruitment was stopped based on the lack of an interaction on IGF-I levels, which was a primary end point for the study. Thirty-six patients have dropped out of the study, 17 because of adverse events and 19 for various other reasons. One stage I endometrial cancer occurred in a patient on fenretinide, and one optic nerve ischemia and one deep venous thrombosis occurred on tamoxifen. There was no difference in menopausal symptoms, endometrial thickness, polyps, or ovarian cysts among treatment arms. To date, 24 breast cancers have been observed, without differences among arms.

CONCLUSION

The combination of low-dose tamoxifen and fenretinide is safe but not synergistic in lowering IGF-I levels in premenopausal women. The clinical implications require further follow-up.

The effects of aromatase inhibitors on lipids and thrombosis

Oestrogen is known to influence blood lipid levels and though its cardioprotective effects are less clear than once thought, there remains concern that reduction of oestrogen levels during hormonal treatment for breast cancer may have an adverse effect on cardiovascular risk. While tamoxifen has been shown to improve lipid profiles, the aromatase inhibitors have a very different mode of action and do not possess the oestrogen-agonistic effects of tamoxifen. At present, there are few data on the effects of these agents on lipid profiles. Available data are mixed, but suggest that the different aromatase inhibitors have different effects on lipid profiles. Some studies show anastrozole as generally having little effect on lipids, while others have indicated adverse effects on lipid profiles/increased hypercholesterolaemia. Letrozole has been associated with adverse effects on lipid profiles in some studies, including BIG 1-98, but short-term data from randomised trials do not show increased cardiovascular morbidity. By contrast, exemestane, which has been studied in slightly more detail, may either have little effect or may be associated with slightly improved lipid profiles. In general, the changes have been small and are likely to be of little relevance in women with advanced breast cancer, but if these agents come to be used in early breast cancer, their impact on lipid profiles may become more important. Many studies are currently underway with the aromatase inhibitors, with safety assessments including monitoring lipid levels. The results of these studies are keenly awaited.

Insulin-like growth factor-1 and binding protein-3 in a 2-year soya intervention among premenopausal women

Soya foods may protect against the development of breast cancer. Insulin-like growth factor (IGF)-1 is under investigation as a possible link between nutrition and cancer. We examined the effect of soya foods on circulating IGF-1 and IGF binding protein (BP)-3 levels among 196 healthy premenopausal women in a 2-year randomised nutritional trial. The intervention group consumed two daily servings of soya foods including tofu, soya milk, soya nuts and soya protein powder (equivalent to 50 mg isoflavones and 5-22 g soya protein per serving); the controls maintained their regular diet. Five serum samples at baseline, 3, 6, 12, and 24 months were collected in the morning during the luteal phase and analysed for IGF-1 and IGFBP-3 by double-antibody ELISA. We applied mixed models to investigate the intervention effect and predictors of serum levels while considering the repeated measurement design. Adherence with the study regimen was high and dropout rates were acceptable. Randomisation resulted in similar mean IGF-1 and IGFBP-3 levels by group. We did not observe a significant intervention effect on IGF-1, IGFBP-3, and their molar ratio during the entire study period. However, urinary isoflavone excretion during the study period was positively associated with IGF-1 (P=0.04) and the IGF-1:IGFBP-3 ratio (P=0.06). The effect was consistent over time. Adding soya foods to the diet of premenopausal women does not appear to lower serum levels of IGF-1 and IGFBP-3; if anything, the greater protein intake from soya may lead to a small increase in IGF-1 serum levels.

SERMs in chemoprevention of breast cancer

Selective estrogen receptor modulators (SERMs) play a key role in breast cancer chemoprevention. Tamoxifen has been shown to reduce breast cancer incidence by 30-40% in at-risk subjects in large phase III trials. However, toxicity may be a limiting factor. Thus, different strategies are being pursued to improve the risk: benefit ratio of using these compounds in chemoprevention. Firstly, the second generation SERM raloxifene is currently undergoing evaluation in comparison with tamoxifen in a large phase III trial. Also, lower doses of tamoxifen are being assessed in phase II-III trials. In addition, the combination of hormone replacement therapy (HRT) or aromatase inhibitors and tamoxifen at low doses may reduce the risks while retaining the benefits of either agents. Finally, new agents that interfere with the onset of ER-negative breast cancer are being sought for combination chemoprevention since almost a third of breast cancers will not be sensitive to hormonal modulation.

Chemoprevention: From research to clinical oncology

Chemoprevention is by now an emerging area of clinical oncology addressed to healthy individuals at higher risk for cancer, subjects with precancerous conditions, and patients who are at risk for a second primary cancer. The important results of large trials with various agents and the more accurate methods of risk assessment have already had implications in clinical practice. Recently, a number of compounds have shown to be clinically effective at various organ levels, often covering all the three settings of primary, secondary and tertiary prevention. There is proof today that at least 3 of the 4 'big killers' in oncology--breast, colon and prostate cancer--and oral cancer are to a certain extent preventable by chemopreventive drugs. The missing piece so far is lung cancer. The expanding molecular drug development is providing the tools for a more effective and safer molecular-targeted prevention. Combination chemoprevention and the use of agents with multiple effects are other particularly promising chemoprevention strategies.