American Society of Clinical Oncology technology assessment on the use of aromatase inhibitors as adjuvant therapy for women with hormone receptor-positive breast cancer: status report 2002

Effects of toremifene (TOR) and tamoxifen (TAM) on serum lipids in postmenopausal patients with breast cancer

This study clarified the difference in the effects on serum lipids between toremifene (TOR) and tamoxifen (TAM). To remove influencing factors, we investigated adjuvant therapy for hormone receptor-positive patients with breast cancer without lymph node metastasis. The subjects were 65 patients who were enrolled in a multicenter randomized comparative study between April 1997 and March 2001. As adjuvant therapy, 20 mg of TAM or 40 mg of TOR was administered for 1 year. The levels of triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A-1 (Apo A-1), apolipoprotein A(Apo B), and lipoprotein a (Lp(a)) were measured prior to administration and 3, 6, and 12 months after the start of administration. TC, LDL-C, Lp(a) and Apo B significantly decreased from the third month of administration compared with values before the start of administration in both the TOR and TAM groups. HDL-C significantly increased from the third month only in the TOR group. TG significantly increased in the TAM group but significantly decreased in the TOR group in the 12th month of administration. When these two groups were compared, HDL-C was significantly higher (p < 0.01) and TG was significantly lower (p < 0.01) in the TOR group in the 12th month. Improvement of abnormal values of TG, HDL-C and LDL-C was better in the TOR group than in the TAM group after administration for 12 months. The effect on lipid metabolism showed different profiles between the two selective estrogen receptor modulators (SERMs), and TOR gave better results than TAM.

The choice of systemic adjuvant therapy in receptor-positive early breast cancer

Patients with endocrine-responsive breast cancer represent a distinct population for which tailored adjuvant treatments are needed. Endocrine therapy is mandatory for this population. For premenopausal patients, ovarian ablation or tamoxifen can be recommended; the combination of both, as well as the combination of ovarian ablation and aromatase inhibitors is under investigation. For postmenopausal patients, tamoxifen for 5 years is the 'standard of care'. Anastrozole can be recommended for patients with a contraindication to tamoxifen. The addition of 5 years of letrozole after 5 years of tamoxifen has yielded benefits in terms of disease-free survival. The sequential use of tamoxifen and exemestane was superior to tamoxifen for 5 years. However, in both studies, long-term toxicity is still not fully evaluated. The addition of chemotherapy to endocrine treatment can be recommended for patients at high risk of relapse and in young patients. Chemotherapy should consist of 3-6 cycles of cyclophosphamide, methotrexate, 5-fluorouracil or of an anthracycline-containing regimen. The addition of taxanes cannot be routinely recommended in this population. Endocrine treatment should start after completion of chemotherapy.

Endocrine Therapy Trials of Aromatase Inhibitors for Breast Cancer in the Adjuvant and Prevention Settings

The recent past has witnessed the appearance of substantial data relating to endocrine therapy of breast cancer. In the adjuvant therapy setting in early breast cancer, several large, well-conducted, randomized, double-blind clinical trials have provided evidence for the value of the third-generation aromatase inhibitors (AI) anastrozole, exemestane, and letrozole. The three major studies to date [i.e., Arimidex, tamoxifen alone, or in combination (ATAC), International Exemestane Study (IES), and letrozole after 5 years of tamoxifen (MA.17)] evaluated three different populations of women from the standpoints of duration of prior tamoxifen and thus time since the treatment of the primary breast cancer. A consistent pattern of improvement in disease-free survival was seen whether the control arm was tamoxifen (ATAC and IES) or placebo following tamoxifen (MA.17). From a toxicity standpoint, the major findings with the AIs were a decreased incidence of thromboembolic events and endometrial cancers but an increase in musculoskeletal complaints and potential for decreasing bone density. The last issue should be clarified with ongoing studies addressing the impact of the three AIs on bone density and fractures. In summary, based on ATAC, IES, and MA.17, respectively, the following conclusions can be drawn relating to postmenopausal women with hormone receptor positive early breast cancer: anastrozole is a reasonable choice for initial endocrine adjuvant therapy, exemestane should be considered for women who have received 2 to 3 years of tamoxifen, and letrozole should be considered for those who have completed about 5 years of tamoxifen.

In the prevention setting, tamoxifen has been evaluated in multiple trials involving &gt;28,000 women and, despite clear evidence of benefit, the level of acceptance of this agent by women seems to be low. Two recently developed prevention trials, IBIS 2 and MAP.3, involve the study of aromatase inhibitors against a placebo control rather than tamoxifen. Whereas the recent adjuvant trials have established the value of the third-generation aromatase inhibitors in early-stage breast cancer, the marked reductions in contralateral breast cancers seen in these trials suggest they will be of value in the prevention setting in women at increased risk of developing the disease.

Prevention of Hormone-Related Cancers: Breast Cancer

Carcinogenesis in the breast is a hormonally dependent process. Evidence implicating estrogen as a key breast carcinogen comes from various lines of investigation. Traditional epidemiologic studies demonstrate associations between estrogen exposure, both exogenous and endogenous, and increased breast cancer risk. Ongoing genetic epidemiologic studies also show associations between specific polymorphisms in estrogen-metabolizing genes and risk, albeit inconsistently. The application of these findings to the treatment and, more recently, the prevention of breast cancer has led to the development of agents that either (1) inhibit estrogen action at the estrogen receptor (selective estrogen receptor modulators (SERMs]); or (2) inhibit estrogen-synthesizing enzymes, thereby abrogating synthesis of this hormone (aromatase inhibitors). Large phase III trials have evaluated the ability of such agents to reduce the incidence of breast cancer in women at increased risk of the disease. The National Surgical Adjuvant Breast and Bowel Project (NSABP) P-1: Breast Cancer Prevention Trial (BCPT) demonstrated the superiority of the SERM tamoxifen to placebo in reducing breast cancer risk, leading to the Food and Drug Administration approval of tamoxifen for risk reduction. The implementation of tamoxifen for this indication has not become widespread in clinical practice, however, for a variety of reasons that we discuss. Results from the NSABP Study of Tamoxifen and Raloxifene, which compares the risk-reducing efficacy as well as toxicity of these two SERMs in a similar high-risk population, will be available in the near future. Based on promising data involving reduction of contralateral breast cancer risk in adjuvant studies, several aromatase inhibitors, including letrozole, anastrozole, and exemestane, are being incorporated into trials evaluating their efficacy as preventive agents in women at increased risk.

Switching trial of adjuvant tamoxifen with an aromatase inhibitor in postmenopausal patients with breast cancer

Tamoxifen is currently a standard of care for postmenopausal patients with breast cancer with hormone receptor-positive tumors who are candidates for adjuvant endocrine therapy. This treatment is highly effective and relatively safe. However, a significant proportion of women are constitutively resistant or become resistant to tamoxifen, despite having hormone receptor-positive tumors. Moreover, the prolonged exposure to tamoxifen can produce severe and life-threatening side effects like endometrial carcinoma or thromboembolic disease. Aromatase inhibitors (AI) have been shown to be quite effective in advanced disease, and also have promising efficacy in early-stage breast cancer as alternatives to tamoxifen. This article reviews the results achieved by AI following 2-3 years or 5 years of tamoxifen. At least 3 trials indicate that switching to an AI following 2-3 years of tamoxifen can produce a substantial benefit. A fourth trial indicates that additional benefit can be achieved by a few years of treatment with an AI after 5 years of tamoxifen. The updated results of previous trials and ongoing trials will soon establish criteria for selecting patients who might be better candidates for sequencing, and to fine tune strategies that are more appropriate.

American Society of Clinical Oncology technology assessment on the use of aromatase inhibitors as adjuvant therapy for postmenopausal women with hormone receptor-positive breast cancer: status report 2004

PURPOSE

To update the 2003 American Society of Clinical Oncology technology assessment on adjuvant use of aromatase inhibitors.

RECOMMENDATIONS

Based on results from multiple large randomized trials, adjuvant therapy for postmenopausal women with hormone receptor-positive breast cancer should include an aromatase inhibitor in order to lower the risk of tumor recurrence. Neither the optimal timing nor duration of aromatase inhibitor therapy is established. Aromatase inhibitors are appropriate as initial treatment for women with contraindications to tamoxifen. For all other postmenopausal women, treatment options include 5 years of aromatase inhibitors treatment or sequential therapy consisting of tamoxifen (for either 2 to 3 years or 5 years) followed by aromatase inhibitors for 2 to 3, or 5 years. Patients intolerant of aromatase inhibitors should receive tamoxifen. There are no data on the use of tamoxifen after an aromatase inhibitor in the adjuvant setting. Women with hormone receptor-negative tumors should not receive adjuvant endocrine therapy. The role of other biomarkers such as progesterone receptor and HER2 status in selecting optimal endocrine therapy remains controversial. Aromatase inhibitors are contraindicated in premenopausal women; there are limited data concerning their role in women with treatment-related amenorrhea. The side effect profiles of tamoxifen and aromatase inhibitors differ. The late consequences of aromatase inhibitor therapy, including osteoporosis, are not well characterized.

CONCLUSION

The Panel believes that optimal adjuvant hormonal therapy for a postmenopausal woman with receptor-positive breast cancer includes an aromatase inhibitor as initial therapy or after treatment with tamoxifen. Women with breast cancer and their physicians must weigh the risks and benefits of all therapeutic options.

The role of aromatase inhibitors in the adjuvant treatment of breast carcinoma: the M. D. Anderson Cancer Center evidence-based approach

BACKGROUND

The authors examined the published evidence on the use of aromatase inhibitors (AIs) in the adjuvant setting in postmenopausal, hormone receptor-positive patients, and they provide recommendations for clinical management in 3 different situations: newly diagnosed women, women who have already received tamoxifen for 2-3 years, and women who have completed 5-years of tamoxifen and are disease free.

METHODS

All double-blind, randomized, prospective studies were reviewed. Data sources included the MEDLINE data base, reviews, editorials, and experts.

RESULTS

The Arimidex, Tamoxifen Alone or in Combination (ATAC) trial, the Intergroup Exemestane Study (IES), and the MA-17 trial confirmed the superiority of AIs over tamoxifen in women with early-stage breast carcinoma, improving disease-free survival (DFS) considerably. In the ATAC trial, the 4-year DFS rate was 86.9% on anastrozole and 84.5% on tamoxifen (P = 0.03); in the IES, the 3-year DFS rate was 91.5% on exemestane and 86.8% on tamoxifen (P = 0.00005); and, in MA-17, the 4-year estimated DFS rate was 93% on letrozole and 87% on placebo (P < or = 0.001). All studies were limited because of the immaturity of data, particularly concerning long-term safety. A negative impact on bone health was observed in all three trials. However short-term side effects were acceptable. In addition, the studies demonstrated a significant reduction in the frequency of new primary tumors in the contralateral breast.

CONCLUSIONS

Current data support anastrozole as first-line adjuvant hormonal therapy, or a change to AIs after 2-3 years of tamoxifen, or the use of letrozole at the end of a 5-year course of tamoxifen as first-choice treatment options for the management of hormone receptor-positive breast carcinoma in postmenopausal women. Ongoing clinical trials should help to define the precise timing, duration, and sequencing of AI therapy, in addition to the long-term tolerability profile and potential differences between anastrozole, letrozole, and exemestane.

Biochemical and biological characterization of a novel anti-aromatase coumarin derivative

Estrogen stimulates the proliferation of estrogen receptor (ER)-positive breast cancer cells. Aromatase is the enzyme responsible for the conversion of androgens into estrogens, and synthetic aromatase inhibitors such as letrozole, anastrozole, and exemestane have proven to be effective endocrine regimens for ER-positive breast cancer. In a recent study, we have found that 4-benzyl-3-(4'-chlorophenyl)-7-methoxycoumarin is a potent competitive inhibitor of aromatase with respect to the androgen substrate. Its K(i) value was determined to be 84 nm, significantly more potent than several known aromatase inhibitors. The specific interaction of this compound with aromatase was further demonstrated by the reduction of its binding by several mutations at the active site region of aromatase and evaluated by computer modeling analysis. The structure-activity studies have revealed that three functional groups (i.e. 3-(4'-chlorophenyl), 4-benzyl, and 7-methoxyl) of this coumarin are important in its inhibition of aromatase. In addition, through a matrigel thread three-dimensional cell culture, this compound was shown to behave like known aromatase inhibitors that suppress the proliferation of aromatase and estrogen receptor positive MCF-7aro breast cancer cells. This coumarin has been shown not to be cytotoxic at up to 40 mum. It was found not to be an inhibitor of steroid 5alpha-reductase that also utilizes androgen as the substrate and not to be a ligand of ERalpha, ERbeta, estrogen-related receptors, or androgen receptor. These results demonstrate that coumarins (a common type of phytochemical) or their derivatives can be potent inhibitors of aromatase and may be useful in suppressing aromataseand ER-positive breast tumors.

Implications of first-line adjuvant treatment with aromatase inhibitors in recurrent metastatic breast cancer

The role of adjuvant tamoxifen therapy has gone unchallenged until recently. With the introduction of the selective aromatase inhibitors (AIs), the paradigm for treatment of hormone receptor-positive breast cancer in postmenopausal women is changing. New data from randomized clinical trials have shown the impact of the use of an AI compared with tamoxifen or in sequence with tamoxifen. This review will emphasize some of the highlights from these data sets and the limitations of our current knowledge. Finally, we will discuss the implications of the use of nonselective AIs in the adjuvant setting for the patient who develops recurrent metastatic disease.

interferon regulatory factor-1 mediates the proapoptotic but not cell cycle arrest effects of the steroidal antiestrogen ICI 182,780 (faslodex, fulvestrant)

Antiestrogens induce both cytostasis (cell cycle arrest) and apoptosis, but the relationship between these end points and the signaling that regulates their induction are unclear. We have previously implicated the transcription factor and putative tumor suppressor IFN regulatory factor-1 (IRF-1) in acquired antiestrogen resistance (Gu et al., Cancer Res, 62: 3428-3437, 2002). We now show the functional significance of IRF-1 in affecting antiestrogen responsiveness in estrogen receptor-positive antiestrogen-sensitive models (MCF-7, T47D, and ZR-75-1), a model of acquired antiestrogen resistance (MCF7/LCC9; estrogen receptor positive), and a model of de novo antiestrogen resistance (MDA-MB-231; estrogen receptor negative). Basal IRF-1 mRNA expression is lower in MCF7/LCC9 cells when compared with MCF-7, T47D, and ZR-75-1 cells. IRF-1 transcriptional activity in MCF-7/LCC9 cells is 18-fold lower than that seen in the parental cells (MCF-7/LCC1) and is comparable with that in MDA-MB-231 cells. Although IRF-1 mRNA expression is induced by ICI 182,780 in sensitive cells, this regulation is lost in MCF-7/LCC9 and is absent in MDA-MB-231 cells. Loss of IRF-1 regulation appears specific to antiestrogen resistance-resistant cells induce IRF-1 mRNA in response to the cytotoxic drug doxorubicin. A dominant-negative IRF-1 eliminates the ICI 182,780-induced apoptotic response (reduced >4-fold) and reduces MCF-7 and T47D cell sensitivity to the antiproliferative effects of ICI 182,780. This effect is not mediated by changes in cell cycle distribution; rather, dominant-negative IRF-1 reduces ICI 182,780-induced apoptosis. These data identify a novel mechanism of antiestrogen resistance and implicate IRF-1 as a key component in signaling some ER-mediated effects on apoptosis/cell survival.

Breast Cancer Highlights: Key Findings from the San Antonio Breast Cancer Symposium: A U.S. Perspective

The San Antonio Breast Cancer Symposium has become one of the leading forums for communication of important discoveries in breast cancer research. Over the past couple of years, seminal, practice-changing results have been presented at this meeting. The aromatase inhibitors represent the most effective endocrine interventions for postmenopausal women with hormone receptor-positive breast cancer. Their introduction into the adjuvant therapy of primary breast cancer was prompted by evidence from the ATAC trial. Progress in adjuvant chemotherapy included the introduction to taxanes, and more recently, the demonstration that the dose-dense administration of paclitaxel in association with doxorubicin and cyclophosphamide resulted in significant improvements in relapse-free and overall survival rates. Molecular targets have become accepted as rational targets, and targeted therapies are proceeding through clinical trials. The success of trastuzumab elicited much excitement, but a number of theoretical and practical hurdles must be overcome before other molecularly targeted agents are incorporated into standard therapy of primary and metastatic breast cancer.

Aromatase inhibitors in the adjuvant setting: bringing the gold to a standard?

The death rate from breast cancer is falling rapidly in most developed countries due, at least in part, to the use of adjuvant endocrine therapy in women with endocrine responsive disease. In post-menopausal women tamoxifen has been the gold standard for nearly 20 years. More recently the aromatase inhibitors (AI) have become established in the management of advanced breast cancer and are being evaluated in the adjuvant setting in trials that include tens of thousands of women. Recently, data have emerged that provide increasingly strong evidence supporting the use of AI in the adjuvant setting. Anastrozole as initial adjuvant endocrine treatment has shown superiority over tamoxifen in terms of disease free survival, and impressive reductions in the risk of recurrence have been demonstrated in trials evaluating the switch from tamoxifen to an AI, either letrozole after 5 or exemestane after 2-3 years of tamoxifen respectively. The data from these recent publications, and the potential impact on routine care of women with post-menopausal breast cancer is discussed.

New findings about endocrine therapy for breast cancer

For over a decade, the selective estrogen receptor modulator, tamoxifen, has been the primary agent for adjuvant endocrine therapy for steroid receptor-positive breast cancer. New data over the last 2 years now suggest that its primacy may be challenged by strategies that lower circulating and/or intratumoral estrogens. Recent trials support the use of ovarian suppression approaches with or without tamoxifen in place of chemotherapy in premenopausal women. A large randomized trial has also established the short-term efficacy and safety of the aromatase inhibitor, anastrozole, in postmenopausal women. How and when to integrate these new approaches into standard practice are topics of debate. Ongoing research is focused on choice of endocrine approach, duration and sequencing of endocrine treatment, identification of better predictive markers for hormone response, and assessment of long-term risks and benefits.

Comments on the St. Gallen Consensus 2003 on the Primary Therapy of Early Breast Cancer

This final paper of the proceedings of the recent Eighth St. Gallen Conference 2003 on the Primary Therapy of Early Breast Cancer comments on the Consensus Paper put forth by the international expert panel and emphasizes new information, that has emerged during the 2 years since the seventh such meeting in 2001. More than 3200 breast cancer specialists from various medical fields-coming from 75 countries and all six continents-have attended the meeting and the process of scientific consensus development. Recommendations for patient care are so critically dependent on assessment of endocrine responsiveness that the importance of high-quality steroid hormone receptor determination and standardized quantitative reporting cannot be overemphasized. The Panel modified and simplified the risk categories so that only endocrine receptor-absent status was sufficient to reclassify an otherwise low-risk, node-negative disease into the category of average risk. Absence of steroid hormone receptors was also recognized as indicating endocrine non-responsiveness. Some important areas highlighted especially in the 2003 consensus include: recognition of the separate nature of endocrine non-responsive breast cancer, both invasive cancers and ductal carcinoma in situ (DCIS); improved understanding of the mechanisms of acquired endocrine resistance, offering exciting prospects for extending the impact of successful sequential endocrine therapies; presentation of high-quality evidence indicating that chemotherapy and tamoxifen should be used sequentially rather than concurrently; availability of a potential alternative to tamoxifen for treatment of postmenopausal women with endocrine responsive disease; promise of newly defined prognostic and predictive markers.

Tamoxifen and Metabolite Concentrations in Serum and Breast Cancer Tissue during Three Dose Regimens in a Randomized Preoperative Trial

PURPOSE

Both therapeutic and adverse effects of tamoxifen may be related to its tissue concentrations. We investigated concentrations of tamoxifen, 4-hydroxytamoxifen, N-desmethyltamoxifen, and N-didesmethyltamoxifen in serum, normal breast, and breast cancer tissues during conventional dosage and two low-dose regimens. Furthermore we studied tamoxifen effects on the cancer proliferation marker Ki-67, and on sex hormone-binding globulin (SHBG).

EXPERIMENTAL DESIGN

From September 1999 to August 2001, 120 breast cancer patients were randomized to 20-, 5-, or 1-mg tamoxifen daily. We measured serum and tissue concentrations of tamoxifen and three metabolites after 28 days of treatment, and the changes between baseline and post-treatment levels of SHBG and Ki-67.

RESULTS

The median (range) tamoxifen concentrations (ng/ml) at doses of 1, 5, and 20 mg daily (n = 38, 37, and 36) were 7.5 (2.9-120.9), 25.2 (1.9-180.9), and 83.6 (8.7-134.4) in serum, and 78.2 (35.9-184), 272.3 (122-641), and 744.4 (208.6-2556) in breast cancer tissue, respectively. Tamoxifen levels followed a dose-concentration relationship. The concentrations of tamoxifen and metabolites were related to each other. Serum and tissue concentrations of tamoxifen were associated with corresponding changes of SHBG levels, whereas changes of Ki-67 levels were not related.

CONCLUSIONS

Estrogen agonistic effects of tamoxifen on SHBG decreased with lower dosage, whereas tamoxifen effects on Ki-67 expression did not change. This together with a >10-fold variation in serum tamoxifen concentrations and a serum to tissue concentration relationship suggest that tamoxifen treatment may be improved by administration of lower doses and therapeutic drug monitoring.

New developments in endocrine therapy: role of adjuvant therapy for early breast cancer

Tamoxifen has become the standard of care in relation to hormonal therapy for women with hormone-sensitive tumors. However, recently completed and ongoing studies indicate that third-generation aromatase inhibitors may be more effective than tamoxifen for a wide range of patients with breast cancer. Drugs in this class currently are approved as first-line endocrine therapy for postmenopausal women with metastatic hormone-dependent breast cancer, and as second-line endocrine therapy after failure of antiestrogen therapy alone or multiple hormonal therapies. The interim results from the Arimidex, Tamoxifen Alone or in Combination Trial support the use of an aromatase inhibitor as an alternative to tamoxifen for adjuvant therapy in postmenopausal women with operable breast cancer that is hormone positive. In this trial, anastrozole had a favorable side effect profile, with fewer cases of endometrial cancer and fewer thromboembolic events than tamoxifen. Other recent studies have indicated that an aromatase inhibitor may be superior to tamoxifen as preoperative treatment for women with hormone-sensitive, primary breast cancer. Numerous clinical trials currently are comparing the efficacy of aromatase inhibitors with that of tamoxifen used as adjuvant therapy for postmenopausal women who have early-stage breast cancer. The results of these trials will provide additional information about the best ways to use these powerful agents for patients with breast cancer.

Clinical practice guidelines for the care and treatment of breast cancer: 15. Treatment for women with stage III or locally advanced breast cancer

OBJECTIVE

To define the optimal treatment for women with stage III or locally advanced breast cancer (LABC).

EVIDENCE

Systematic review of English-language literature retrieved from MEDLINE (1984 to June 2002) and CANCERLIT (1983 to June 2002). A nonsystematic review of the literature was continued through December 2003.

RECOMMENDATIONS

The management of LABC requires a combined modality treatment approach involving surgery, radiotherapy and systemic therapy. Systemic therapy: chemotherapy. Operable tumours. Patients with operable stage IIIA disease should be offered chemotherapy. They should receive adjuvant chemotherapy following surgery, or primary chemotherapy followed by locoregional management. Chemotherapy should contain an anthracycline. Acceptable regimens are 6 cycles of FAC, CAF, CEF or FEC. Taxanes are under intense investigation. Inoperable tumours. Patients with stage IIIB or IIIC disease, including those with inflammatory breast cancer and those with isolated ipsilateral internal mammary or supraclavicular lymph-node involvement, should be treated with primary anthracycline-based chemotherapy. Acceptable chemotherapy regimens are FAC, CAF, CEF or FEC. Taxanes are under intense investigation. Patients with stage IIIB or IIIC disease who respond to primary chemotherapy should be treated until the response plateaus or to a maximum of 6 cycles (minimum 4 cycles). Patients with stage IIIB disease should then undergo definitive surgery and irradiation. The locoregional management of patients with stage IIIC disease who respond to chemotherapy should be individualized. In patients with stage IIIB or IIIC disease who achieve maximum response with fewer than 6 cycles, further adjuvant chemotherapy can be given following surgery and irradiation. Patients whose tumours do not respond to primary chemotherapy can be treated with taxane chemotherapy or can proceed directly to irradiation followed by modified radical mastectomy, if feasible. Systemic therapy: hormonal therapy. Operable and inoperable tumours. Tamoxifen for 5 years should be recommended to pre- and postmenopausal women whose tumours are hormone responsive. Locoregional management. Operable tumours. Patients with stage IIIA disease should receive both modified radical mastectomy (MRM) and locoregional radiotherapy if feasible. They may be managed with MRM followed by chemotherapy and locoregional radiotherapy, or chemotherapy first followed by MRM and locoregional radiotherapy. Breast-conserving surgery is currently not a standard approach. Locoregional radiotherapy should be delivered to the chest wall and to the supraclavicular and axillary nodes. The role of internal mammary irradiation is unclear. Inoperable tumours. Patients with stage IIIB disease who respond to chemotherapy should receive surgery plus locoregional radiotherapy. The locoregional management of patients with stage IIIC disease who respond to chemotherapy is unclear and should be individualized. Patients whose disease remains inoperable following chemotherapy should receive locoregional radiotherapy with subsequent surgery, if feasible.

VALIDATION

The authors' original text was revised by members of the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer. Subsequently, feedback was provided by 9 oncologists from across Canada. The final document was approved by the steering committee.

SPONSOR

The Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer was convened by Health Canada. Completion date: December 2003.

Endocrine prevention of breast cancer using selective oestrogen receptor modulators (SORMs)

Breast cancer remains the most common malignancy in women worldwide. Oestrogen levels appear to be associated with an increased risk for the development of breast cancer. The Early Breast Cancer Trialists' Cooperative Group reported in a 1998 meta-analysis of 37000 breast cancer patients in 55 randomized adjuvant trials that tamoxifen, a selective oestrogen receptor modulator, reduced the incidence of contralateral breast cancers by 47% at 5 years. Tamoxifen has been shown in numerous prevention studies to decrease the incidence of breast cancer in high-risk women. Overall, the tamoxifen prevention trials showed a 38% reduction in the incidence of breast cancer (95% CI 28-46; P<0.0001). In the largest risk-reduction trial, the Breast Cancer Prevention Trial conducted by the National Surgical Adjuvant Breast and Bowel Project, tamoxifen reduced the risk of invasive breast cancer by 49% (two-sided P<0.00001), and non-invasive breast cancer by 50% (P<0.002). The occurrence of oestrogen receptor-(OR)-positive tumours decreased by 69%. Tamoxifen reduces the risk of developing oestrogen receptor-positive tumours, but OR-negative tumours are not affected. Rare but life-threatening side-effects of tamoxifen include endometrial carcinoma, thromboembolic events and cerebrovascular events. Less serious side-effects include cataracts, vasomotor instability, nausea and vaginal discharge. Raloxifene, a second-generation selective oestrogen receptor modulator, is approved for treatment of osteoporosis in post-menopausal women in the USA but it is not currently approved for breast cancer prevention outside of a clinical trial. Prevention studies involving raloxifene and aromatase inhibitors are currently being conducted.

First-line endocrine treatment of breast cancer: aromatase inhibitor or antioestrogen?

Until recently, endocrine therapy for breast cancer was relatively simple. If the tumour expressed hormone receptors, regardless of stage and age, tamoxifen was indicated. While this largely remains the case for premenopausal women, clinical trials in postmenopausal women have broadened our choice to include one of three selective aromatase inhibitors (AIs), the nonsteroidal agents anastrozole or letrozole and the steroidal agent exemestane. Comparative data concerning the efficacy, toxicity, tolerability and cost of AI vs tamoxifen continues to evolve with over 40 000 women slated to be involved in clinical trials. Currently, tamoxifen remains an appropriate choice for adjuvant treatment, and will remain so unless a clear survival advantage emerges for adjuvant AI therapy. However, anastrozole is widely seen as a useful alternative, with particular merit for patients prone to the development of serious tamoxifen side effects. For endocrine therapy naïve advanced disease, several trials have provided evidence that a nonsteroidal AI has replaced tamoxifen as optimal treatment. In the neoadjuvant setting, letrozole was also more effective than tamoxifen, both in terms of response rates and the incidence of breast-conserving surgery, and so AI therefore also dominates this evolving indication. The ongoing adjuvant clinical trials ask all the relevant questions regarding tamoxifen and AI in combination, sequence and duration, except for 5 years of an AI vs a longer period. For both the advanced and early-stage disease, resistance remains the key obstacle to overcome, and trials that combine endocrine agents with signal transduction inhibitors such as HER1 and HER2 kinase inhibitors, farnesyl transferase inhibitors, mTOR inhibitors as well as COX2 inhibitors are being developed in a concerted attempt to address this problem.

Follow-up care of breast cancer survivors

Breast cancer survivors may have several medical and psychosocial concerns in follow-up care. Women with a history of breast cancer should be followed for local-regional recurrence or metastatic disease, as well as for the development of a second primary breast cancer in the contralateral breast. Regular follow-up visits can foster an ongoing patient-clinician relationship both to ensure adequate surveillance and so that symptoms of recurrence or complications of therapy will be reported by the patient and addressed promptly. There are multiple possible long-term complications that may arise following breast cancer treatment, many of which may be ameliorated with various therapies. Clinicians can also provide guidance and counseling as well as psychosocial support to patients regarding medical and psychosocial decisions that may be affected by their personal history of breast cancer.

The proliferative effects of 5-androstene-3 beta,17 beta-diol and 5 alpha-dihydrotestosterone on cell cycle analysis and cell proliferation in MCF7, T47D and MDAMB231 breast cancer cell lines

Epidemiological studies suggest that precursor steroids are implicated in the aetiology of breast cancer. However, our understanding of the role of precursor steroids in breast cancer is complicated by fact that there are many precursor steroids, which are metabolically inter-related and have divergent proliferative activities on the growth of breast cancer cell lines. In this study the proliferative affects of 5 alpha-dihydrotestosterone and 5-androstene-3 beta,17 beta-diol, which may be considered true metabolites acting at a tissue level, on MCF7, T47D and MDAMB231 breast cancer cell lines have been examined by a flow cytometric technique. DNA cell cycle analysis demonstrates that 5-androstene-3 beta,17 beta-diol stimulates the proliferation of hormone-dependent cell lines at physiological levels by an oestrogen receptor mediated mechanism whereas 5 alpha-dihydrotestosterone does not affect the proliferation of MCF7 and T47D cell lines at physiological levels over short (48 h) incubations. Both 5 alpha-dihydrotestosterone and 5-androstene-3 beta,17 beta-diol stimulate proliferation of hormone-dependent cell lines at pharmacological levels via and interaction with the oestrogen receptor. In long (6-9 days) incubations both 5 alpha-dihydrotestosterone and 5-androstene-3 beta,17 beta-diol inhibit the 17 beta-oestradiol induced proliferation of MCF7 and T47D cell lines, however, 5 alpha-dihydrotestosterone inhibits while 5-androstene-3 beta,17 beta-diol stimulates basal proliferation. These cell line studies suggest a model for the role of precursor steroids in pre- and postmenopausal breast cancer.

Benefit and projected cost-effectiveness of anastrozole versus tamoxifen as initial adjuvant therapy for patients with early-stage estrogen receptor-positive breast cancer

BACKGROUND

Women who have estrogen receptor (ER)-positive disease with postmenopausal onset and who receive tamoxifen as standard adjuvant treatment constitute the largest subgroup of patients with breast cancer. Recent data from the ATAC ('Arimidex, Tamoxifen Alone or in Combination') randomized trial indicate that anastrozole significantly reduces breast cancer recurrence rates but does not provide any advantage in terms of survival at 4 years posttreatment. Furthermore, anastrozole and tamoxifen were found to have different toxicity profiles. The goals of the current study were to estimate the disease-free survival (DFS) rates and potential survival benefits associated with anastrozole use and to determine whether the incremental cost-effectiveness (ICE) was low enough to warrant an immediate switch to the use of this agent, as the long-term conclusions of the ATAC trial will not be available for several years.

METHODS

A computer simulation model assessed the outcomes of 64-year-old women with ER-positive breast cancer who subsequently received either anastrozole or tamoxifen for 5 years. Daily recurrence risks, as well as the relative risks associated with various treatment-related events, were calculated using data from the ATAC trial. Study endpoints included breast cancer recurrence-free survival, anticipated survival resulting from an anastrozole-induced decrease in systemic disease recurrence rates, and survival adjusted for quality of life and for hip fracture risk over periods of 4, 12, and 20 years.

RESULTS

After 4 years, the projected DFS benefit associated with anastrozole was 14 days, with an ICE of $167,500 per year. Projected 12 and 20 years into the future, DFS benefits increased to 2.9 months and 5.3 months, respectively. The corresponding benefits in terms of overall survival were 0.9 months and 2.0 months, respectively, with the ICE becoming < $100,000 per life year once the projection horizon exceeded 12 years. The inclusion of quality-of-life weightings for nonfatal outcomes modestly favored anastrozole in the short term; however, if anastrozole use is associated with an increased risk of hip fracture, then the long-term benefit associated with this agent is reduced by approximately 25%.

CONCLUSIONS

Adjuvant anastrozole is projected to result in a substantial improvement in DFS for patients with breast cancer. If this DFS benefit were to ultimately lead to a survival benefit, then the ICE of anastrozole use would be acceptable for patients expected to live longer than 12 years. Decision models are useful for generating realistic projections for stakeholders who are considering competing options that impact survival and quality of life and have associated societal costs.

Advances in endocrine treatments for postmenopausal women with metastatic and early breast cancer

For the past 25 years, the estrogen antagonist tamoxifen has been the hormonal treatment of choice for postmenopausal patients with hormone-sensitive metastatic and early breast cancer (EBC). However, tamoxifen is associated with certain tolerability and safety concerns. In addition, the hormonal options after progression are limited, and thus, alternative endocrine treatments have been developed. This review provides a synopsis of the newer alternatives in endocrine therapy of breast cancer: the aromatase inhibitors (AIs) and fulvestrant Faslodex), the estrogen receptor antagonist that downregulates estrogen and progesterone receptors and has no known agonist activity. The third-generation AIs, anastrozole and letrozole, have been shown to be as effective or more effective than megestrol acetate and tamoxifen as second- and first-line therapies for the treatment of postmenopausal patients with metastatic breast cancer, and exemestane has been approved for second-line use. Fulvestrant has been shown to be as effective as anastrozole as second-line therapy for metastatic breast cancer and has been approved in the U.S. for the treatment of postmenopausal women with hormone-receptor-positive metastatic breast cancer following progression on antiestrogen therapy. Anastrozole is the only AI with published clinical trial data and U.S. Food and Drug Administration approval for adjuvant therapy of postmenopausal women with EBC. The 'Arimidex,' Tamoxifen, Alone or in Combination (ATAC) trial, a double-blind, multicenter trial with 9,366 patients, compared tamoxifen with anastrozole, alone and in combination, as adjuvant endocrine treatment for postmenopausal patients with operable, invasive, EBC. The first analysis (at a median follow-up of 33.3 months) showed longer disease-free survival and, in general, better tolerability with anastrozole than with tamoxifen. This pattern was maintained at later analyses with a median follow-up of 47 months for efficacy and 37 months for safety and tolerability. Although longer follow-up is warranted, anastrozole appears to be a well-documented choice of endocrine adjuvant therapy for postmenopausal women with hormone-responsive breast cancer.

Second cancers after breast cancer treatment

Breast irradiation, adjuvant chemotherapy, and tamoxifen are associated with an increased risk of second cancers that may manifest decades after treatment. Although very small, it is nonetheless important for clinicians and women to be aware of and to recognize the risk. Postmastectomy irradiation is associated with a slight increase in the risk of developing a sarcoma or lung cancer after a latency period of more than 10 years. However, the majority of information on radiation-associated cancers is derived from large tumor registries, which reflect outdated radiation treatment practices. Modern treatment approaches, which use lower fraction size (or dose) and limit the exposure of surrounding normal tissue to radiation, are less likely to cause radiation-associated cancers. Adjuvant chemotherapy is not associated with any detectable increased risk of solid tumors beyond that which occurs as the population ages. However, alkylating agents, such as cyclophosphamide, and the topoisomerase II inhibitors, doxorubicin and epirubicin, are associated with two types of cytogenetically distinct leukemias after adjuvant chemotherapy. The absolute risk of developing leukemia is lower by orders of magnitude than the improvement in breast cancer mortality that results from adjuvant chemotherapy. Tamoxifen is associated with a two- to threefold increase in the risk of developing endometrial cancer, or about 80 excess cases per 10,000 treated women at 10 years. The benefits of adjuvant therapy outweigh the risks of developing second cancers. Additional studies are needed to more precisely identify patients who are or are not likely to benefit from adjuvant therapy, and individual host and treatment factors that influence the development of second cancer.

The best use of adjuvant endocrine treatments

Endocrine therapy remains important in the adjuvant treatment of pre- and postmenopausal women. Adjuvant ovarian ablation with or without tamoxifen produces effects which are equivalent to those of CMF (cyclophosphamide, methotrexate and 5-fluorouracil) chemotherapy in premenopausal women with oestrogen receptor (ER) and/or progesterone receptor (PgR) positive breast cancer. Tamoxifen alone is also effective in these women. Concurrent use of tamoxifen and ovarian ablation may be even more effective, but more studies are needed. Tamoxifen remains a standard adjuvant therapy for postmenopausal women with ER and/or PgR positive tumours. Current information supports the use of 5 years of tamoxifen but additional studies comparing 5 years to longer duration are ongoing. The aromatase inhibitor (AI) anastrozole has now been demonstrated to be better than tamoxifen in preventing recurrence in early reports from the Arimidex vs Tamoxifen And the Combination (ATAC) Trial. Ongoing trials of this and other AIs before, after, concurrent with, or substituted for tamoxifen in the adjuvant setting may soon revolutionize our approach for postmenopausal women. Adjuvant bisphosphonates have been shown to reduce the incidence of bone metastases and improve survival in two of three published adjuvant trials and are being further studied. Her-2 neu status is being explored as a predictive factor for selection of endocrine therapy, but is not yet considered standard for this purpose.

Adjuvant therapy for older women with breast cancer

The major risk factor for breast cancer is increasing age and more than half of all breast cancers in affluent nations occur in women 65 years and older. Co-morbidity is a key consideration in offering systemic adjuvant treatment to older women since significant co-morbidity minimizes the potential value of any adjuvant therapy. Tamoxifen has clearly been shown to significantly decrease the risk of recurrence and improve survival in women of all ages who have estrogen (ER) or progesterone receptor (PR) positive invasive breast cancer, including those 70 years and older. Chemotherapy in older patients can improve survival but adds little to tamoxifen in women with node-negative, ER+ or PR+ tumors: it should be reserved for older women who have reasonable life-expectancy and larger node-negative tumors, or node-positive tumors. Ageism is still a barrier to clinical trials participation and clinical trials focusing on older women are needed.

Antiestrogen resistance in breast cancer and the role of estrogen receptor signaling

Antiestrogens include agents such as tamoxifen, toremifene, raloxifene, and fulvestrant. Currently, tamoxifen is the only drug approved for use in breast cancer chemoprevention, and it remains the treatment of choice for most women with hormone receptor positive, invasive breast carcinoma. While antiestrogens have been available since the early 1970s, we still do not fully understand their mechanisms of action and resistance. Essentially, two forms of antiestrogen resistance occur: de novo resistance and acquired resistance. Absence of estrogen receptor (ER) expression is the most common de novo resistance mechanism, whereas a complete loss of ER expression is not common in acquired resistance. Antiestrogen unresponsiveness appears to be the major acquired resistance phenotype, with a switch to an antiestrogen-stimulated growth being a minor phenotype. Since antiestrogens compete with estrogens for binding to ER, clinical response to antiestrogens may be affected by exogenous estrogenic exposures. Such exposures include estrogenic hormone replacement therapies and dietary and environmental exposures that directly or indirectly increase a tumor's estrogenic environment. Whether antiestrogen resistance can be conferred by a switch from predominantly ERalpha to ERbeta expression remains unanswered, but predicting response to antiestrogen therapy requires only measurement of ERalpha expression. The role of altered receptor coactivator or corepressor expression in antiestrogen resistance also is unclear, and understanding their roles may be confounded by their ubiquitous expression and functional redundancy. We have proposed a gene network approach to exploring the mechanistic aspects of antiestrogen resistance. Using transcriptome and proteome analyses, we have begun to identify candidate genes that comprise one component of a larger, putative gene network. These candidate genes include NFkappaB, interferon regulatory factor-1, nucleophosmin, and the X-box binding protein-1. The network also may involve signaling through ras and MAPK, implicating crosstalk with growth factors and cytokines. Ultimately, signaling affects the expression/function of the proliferation and/or apoptotic machineries.

A randomized trial of letrozole in postmenopausal women after five years of tamoxifen therapy for early-stage breast cancer

BACKGROUND

In hormone-dependent breast cancer, five years of postoperative tamoxifen therapy--but not tamoxifen therapy of longer duration--prolongs disease-free and overall survival. The aromatase inhibitor letrozole, by suppressing estrogen production, might improve the outcome after the discontinuation of tamoxifen therapy.

METHODS

We conducted a double-blind, placebo-controlled trial to test the effectiveness of five years of letrozole therapy in postmenopausal women with breast cancer who have completed five years of tamoxifen therapy. The primary end point was disease-free survival.

RESULTS

A total of 5187 women were enrolled (median follow-up, 2.4 years). At the first interim analysis, there were 207 local or metastatic recurrences of breast cancer or new primary cancers in the contralateral breast--75 in the letrozole group and 132 in the placebo group--with estimated four-year disease-free survival rates of 93 percent and 87 percent, respectively, in the two groups (P< or =0.001 for the comparison of disease-free survival). A total of 42 women in the placebo group and 31 women in the letrozole group died (P=0.25 for the comparison of overall survival). Low-grade hot flashes, arthritis, arthralgia, and myalgia were more frequent in the letrozole group, but vaginal bleeding was less frequent. There were new diagnoses of osteoporosis in 5.8 percent of the women in the letrozole group and 4.5 percent of the women in the placebo group (P=0.07); the rates of fracture were similar. After the first interim analysis, the independent data and safety monitoring committee recommended termination of the trial and prompt communication of the results to the participants.

CONCLUSIONS

As compared with placebo, letrozole therapy after the completion of standard tamoxifen treatment significantly improves disease-free survival.

American Society of Clinical Oncology 2003 update on the role of bisphosphonates and bone health issues in women with breast cancer

PURPOSE

To update the 2000 ASCO guidelines on the role of bisphosphonates in women with breast cancer and address the subject of bone health in these women.

RESULTS

For patients with plain radiographic evidence of bone destruction, intravenous pamidronate 90 mg delivered over 2 hours or zoledronic acid 4 mg over 15 minutes every 3 to 4 weeks is recommended. There is insufficient evidence supporting the efficacy of one bisphosphonate over the other. Starting bisphosphonates in women who demonstrate bone destruction through imaging but who have normal plain radiographs is considered reasonable treatment. Starting bisphosphonates in women with only an abnormal bone scan but without evidence of bone destruction is not recommended. The presence or absence of bone pain should not be a factor in initiating bisphosphonates. In patients with a serum creatinine less than 3.0 mg/dL (265 mumol/L), no change in dosage, infusion time, or interval is required. Infusion times less than 2 hours with pamidronate or less than 15 minutes with zoledronic acid should be avoided. Creatinine should be monitored before each dose of either agent in accordance with US Food and Drug Administration (FDA) labeling. Oncology professionals, especially medical oncologists, need to take an expanded role in the routine and regular assessment of the osteoporosis risk in women with breast cancer. The panel recommends an algorithm for patient management to maintain bone health.

CONCLUSION

Bisphosphonates provide a supportive, albeit expensive and non-life-prolonging, benefit to many patients with bone metastases. Current research is focusing on bisphosphonates as adjuvant therapy. Although new data addressing when to stop therapy, alternative doses or schedules for administration, and how to best coordinate bisphosphonates with other palliative therapies are needed, they are not currently being investigated.

Structure-function studies of aromatase and its inhibitors: a progress report

The utilization of computer modeling, site-directed mutagenesis, inhibition kinetic analysis and reaction metabolite analysis allows us to better understand the structure-function relationship between aromatase and its inhibitors. Our results have helped in determining how steroidal and nonsteriodal aromatase inhibitors bind to the active site of the enzyme. This information has also aided in the understanding of the reaction mechanism of aromatase. Furthermore, our structure-function studies of aromatase have generated important information for predicting how environmental chemicals interact with the enzyme. During the last 2 years, a new aromatase computer model based on the X-ray structure of rabbit cytochrome P450 2C5 has been generated and used to evaluate the results obtained from new aromatase mutants produced in this laboratory. In addition, we have succeeded in the expression and purification of functionally active aromatase using an Escherichia coli expression method. The catalytic properties of this recombinant aromatase are similar to those properties exhibited by the human placental aromatase preparation and the mammalian cell-expressed enzyme. The E. coli expressed aromatase will be very useful for further structure-function studies of aromatase. Our laboratory has also evaluated the growth-inhibiting activity of aromatase inhibitors in estrogen receptor-positive breast cancer using three-dimensional cell cultures of aromatase-over expressing MCF-7 and T-47D cell lines (i.e. MCF-7aro and T-47Daro). Our results demonstrate that these three-dimensional cultures are valuable approaches to assess the growth-inhibiting activity of aromatase inhibitors. Finally, we have identified several phytochemicals to be potent inhibitors of aromatase. To demonstrate the impact of the phytochemicals on estrogen formation in vivo, we showed that the intake of anti-aromatase chemicals from red wine was capable of suppressing MCF-7aro-mediated tumor formation in nude mice and aromatase-induced hyperplasia in a transgenic mouse model in which aromatase is over-expressed in the mammary tissue.

The intratumoral aromatase model: studies with aromatase inhibitors and antiestrogens

Aromatase inhibitors have now been approved as first-line treatment options for hormone-dependent advanced breast cancer. When compared to tamoxifen, these aromatase inhibitors provide significant survival and tolerability advantages. However, the optimal use of an aromatase inhibitor and tamoxifen remains to be established. To date, the intratumoral aromatase xenograft model has proved accurate in predicting the outcome of clinical trials. Utilizing this model, we performed long-term studies with tamoxifen and letrozole to determine time to disease progression with each of the treatment regimens. Aromatase-transfected MCF-7Ca human breast cancer cells were grown as tumor xenografts in female ovariectomized athymic nude mice in which androstenedione was converted to estrogen and stimulated tumor growth. When tumor volumes were approximately 300 mm3, the animals were grouped for continued supplementation with androstenedione only (control) or for treatment with letrozole 10 microg per day (long-term), tamoxifen 100 microg per day (long-term), letrozole alternating to tamoxifen (4-week rotation), tamoxifen alternating to letrozole (4-week rotation), or a combination of the two drugs. Tumors of control mice had doubled in volume in 3-4 weeks. In mice treated with tamoxifen and the combination, tumor doubling time was significantly shorter (16 and 18 weeks, respectively) than with letrozole (34 weeks). Furthermore, alternating letrozole and tamoxifen treatment every 4 weeks was less effective than letrozole alone. Tumors doubled in 17-18 weeks when the starting treatment was tamoxifen and in 22 weeks when the starting treatment was letrozole. Tumors progressing on tamoxifen remained sensitive to second-line therapy with letrozole (10 microg per day). However, when mice with letrozole-resistant tumors were switched to antiestrogen treatment, tumors did not respond to tamoxifen (100 microg per day) or faslodex (1 mg per day). This suggests that advanced breast cancers treated with letrozole may be insensitive to subsequent second-line hormonal agents. Thus, although letrozole was determined to be an effective second-line treatment option for tumors progressing on tamoxifen, antiestrogen therapy does not appear to be effective for tumors progressing on letrozole. However, response to second-line treatment was observed in a model where tumors that had progressed on letrozole were transplanted to new mice. These tumors had been allowed to grow in the presence of supplemented androstenedione but absence of letrozole. This suggests that resistance to letrozole may be reversible, allowing tumors to respond to subsequent antiestrogens and letrozole.

Meeting highlights: updated international expert consensus on the primary therapy of early breast cancer

This account of the highlights of the eighth St Gallen (Switzerland) meeting in 2003 emphasizes new information that has emerged during the 2 years since the seventh meeting in 2001. This article should be read in conjunction with the report of that earlier meeting. Recommendations for patient care are so critically dependent on assessment of endocrine responsiveness that the importance of high-quality steroid hormone receptor determination and standardized quantitative reporting cannot be overemphasized. The International Consensus Panel modified the risk categories so that only endocrine receptor-absent status was sufficient to reclassify an otherwise low-risk, node-negative disease into the category of average risk. Absence of steroid hormone receptors also was recognized as indicating endocrine nonresponsiveness. Some important areas highlighted at the recent meeting include: (1) recognition of the separate nature of endocrine-nonresponsive breast cancer-both invasive cancers and ductal carcinoma-in-situ; (2) improved understanding of the mechanisms of acquired endocrine resistance, which offer exciting prospects for extending the impact of successful sequential endocrine therapies; (3) presentation of high-quality evidence indicating that chemotherapy and tamoxifen should be used sequentially rather than concurrently; (4) availability of a potential alternative to tamoxifen for treatment of postmenopausal women with endocrine-responsive disease; and (5) the promise of newly defined prognostic and predictive markers.

Aromatase inhibitors as adjuvant therapies in patients with breast cancer

There is increasing evidence that endocrine therapy has an important role in patients with oestrogen receptor positive breast cancer. Several large meta-analyses have reinforced the value of both ovarian ablation and tamoxifen in improving survival. Over the past decade, aromatase inhibitors have become the treatment of choice for second-line therapy of metastatic breast cancer, and the third generation inhibitors have now an established reputation for good patient tolerability. Early studies indicated that aminoglutethimide/hydrocortisone could benefit postmenopausal patients with primary breast cancer, and in 2001, the ATAC study showed that the third generation aromatase inhibitor, anastrozole, seemed superior to tamoxifen in that anastrozole-treated patients had a longer disease-free survival. Other studies will report on the relative merits of the steroidal inhibitor exemestane as well as non-steroidal letrozole. The exact duration and sequencing of treatment, together with the long-term effects on bone are at present, unknown.

Androgen receptors frequently are expressed in breast carcinomas: potential relevance to new therapeutic strategies

BACKGROUND

Several studies have demonstrated the biologic and therapeutic significance of estrogen and progesterone receptors (ER and PR) in breast carcinomas. The aim of the current study was to examine the presence of androgen receptors (AR) in breast carcinomas.

METHODS

Two hundred cases of breast carcinoma, consisting of 145 invasive and 55 noninvasive (ductal carcinoma in situ [DCIS]) lesions, were examined using a monoclonal antibody against AR on formalin-fixed, paraffin-embedded archival material. The results were analyzed for correlations with immunohistochemically determined ER, PR, and HER-2/neu expression.

RESULTS

Eighty-seven of the 145 cases (60%) of invasive carcinoma and 45 of the 55 cases (82%) of DCIS were AR-positive according to internationally standardized guidelines. The vast majority of Grade 1 carcinomas were positive for AR (90% of invasive Grade 1 carcinomas and 95% of Grade 1 DCIS), whereas in Grade 3 invasive carcinomas and DCIS, positive immunoreactions for AR were observed in 46% and 76% of cases, respectively. Among the cases of Grade 3 carcinoma, 33 invasive carcinomas (39%) and 17 DCIS lesions (68%) were ER-negative but AR-positive. Among Grade 1 carcinomas (invasive and DCIS), not a single case was positive for HER-2/neu, but most cases were intensely positive for AR. In contrast, many invasive Grade 3 carcinomas exhibited agreement between AR status and HER-2/neu status (AR-positive and HER-2/neu-positive, 30.5%; AR-negative and HER-2/neu-negative, 42.5%).

CONCLUSIONS

Androgen receptors are commonly expressed in DCIS and in invasive breast carcinoma. A significant number of poorly differentiated carcinomas are ER-negative and PR-negative but AR-positive. Immunohistochemical examination of AR would be desirable because it would provide additional information about steroid receptors in breast carcinomas.

The current status of aromatase inhibitors in the management of breast cancer

The third generation of specific AIs have made a very exciting contribution to the management of hormone responsive breast cancer. We can now state with confidence that their role in advanced breast cancer has overtaken that of tamoxifen, which should be relegated to a second-line treatment. Indeed, as a recent publication confirmed that first-line anastrozole followed by tamoxifen is an effective treatment sequence, this sequence may be considered the best choice for treating patients with hormone receptor-positive ABC. As far as the primary disease is concerned, the ATAC data certainly suggest that there is an alternative to tamoxifen in selected postmenopausal women with hormone receptor-positive disease. With more mature follow-up the study might even show that after a passage of nearly 20 years tamoxifen has lost its lead position in the adjuvant stakes as well.

A randomized trial of low-dose tamoxifen on breast cancer proliferation and blood estrogenic biomarkers

BACKGROUND

Tamoxifen reduces the risk of breast cancer in women at high risk for the disease but increases the risk for endometrial tumors and venous thromboembolisms, possibly in a dose-dependent fashion. We compared the effects of tamoxifen at 1 mg/day and 5 mg/day with those of the standard dose of 20 mg/day on breast cancer proliferation using a surrogate endpoint marker (Ki-67 expression) and blood biomarkers associated with breast cancer, cardiovascular disease, and bone fracture risk.

METHODS

We randomly assigned 120 women with estrogen receptor (ER)-positive breast cancer to tamoxifen at 1, 5, or 20 mg/day for 4 weeks. Expression of the tumor proliferation marker Ki-67 and of biomarkers of breast cancer (insulin-like growth factor-I, sex hormone-binding globulin), cardiovascular disease (cholesterol, triglycerides, ultrasensitive C-reactive protein, fibrinogen, antithrombin-III), and bone fracture (type I collagen C-telopeptide) risk were determined before (baseline) and after treatment. All levels were compared with those in two nonrandomized control groups (34 women with ER-negative breast cancer and 29 additional women with ER-positive breast cancer). Data were analyzed by analysis of covariance. All statistical tests were two-sided.

RESULTS

Expression of Ki-67 decreased in all three tamoxifen groups, with no difference in the magnitude of reduction among groups (P =.81). Relative to baseline, Ki-67 expression decreased by a median of 15.0% (95% confidence interval = 0.0% to 24.1%) among the tamoxifen groups but increased by 12.8% (95% confidence interval = 0.0% to 19.6%) among the nonrandomized control groups. Several blood biomarkers showed dose-response relationships with tamoxifen, including decreased insulin-like growth factor-I, increased sex hormone-binding globulin, and decreased low-density lipoprotein-cholesterol, ultrasensitive C-reactive protein, fibrinogen, and antithrombin-III levels.

CONCLUSIONS

The effects on Ki-67 expression of lower doses of tamoxifen were comparable to those achieved with the standard dose, although the effects on blood biomarkers were variable. The effects of lower doses of tamoxifen should be assessed further in randomized trials.

Low neuropsychologic performance among adult cancer survivors treated with chemotherapy

Decline in neuropsychologic test performance following adjuvant chemotherapy for various types of cancer has gained much research attention over the past decade. From available data, about one fourth to one third of individuals undergoing systemic chemotherapy exhibit measurable decrements in performance of standard tests of cognitive function. Many cancer survivors report that cognitive problems interfere with function and compromise quality of life. However, these declines appear subtle and there are little available longitudinal data examining pre- to post-treatment cognitive change. Further, there is little available evidence identifying the causes of cognitive decline. This paper reviews current literature on low neuropsychologic performance following systemic chemotherapy and hypotheses on the causes of cognitive symptoms following chemotherapy. Future research directions, with emphasis on longitudinal research design as well as treatment implications, are discussed.

The role of aromatase inhibitors in early breast cancer

The role of hormonal therapy for the treatment of patients with early stage breast cancer has been evaluated in many studies. The results of these studies establish tamoxifen as the gold standard of hormonal therapy for the adjuvant treatment of hormone receptor-positive invasive breast cancer in pre- and postmenopausal women. Studies show tamoxifen reduces the risk of invasive breast cancer in women at increased risk for the disease, including women with ductal carcinoma in situ. Tamoxifen has adverse effects such as hot flashes, increased risk of uterine cancer in postmenopausal women, and rare occurrence of thromboembolic disease. Despite the multiple therapeutic roles of tamoxifen, alternatives are needed. Aromatase inhibitors (AI) are drugs with antiestrogenic activity. AIs function by inhibiting the peripheral conversion of adrenally synthesized androstenedione to estradiol through inhibition of the aromatase enzyme. AIs do not suppress estradiol synthesis by the ovary adequately. Therefore, AIs are effective in reducing circulating estradiol levels in postmenopausal women, but not premenopausal women. Selective nonsteroidal AIs, including anastrozole (Arimidex; AstraZeneca, Wilmington, DE) and letrozole (Femara; Novartis, East Hanover, NJ), and the steroidal AI exemestane (Aromasin; Pharmacia, Peapack, NJ) have been associated with increased specificity and improved therapeutic index compared to nonselective AIs such as aminoglutethamide. Nonsteroidal and steroidal AIs have demonstrated to be superior to megestrol acetate in second-line therapy of postmenopausal women with metastatic breast cancer, and selective nonsteroidal AIs have shown to be superior to tamoxifen in first-line therapy of postmenopausal women with metastatic breast cancer. The ATAC (Arimidex, tamoxifen, alone, or in combination) trial is the only published randomized trial comparing the efficacy of an AI to tamoxifen for the adjuvant treatment of women with early breast cancer. This large study showed that at a median follow-up time of 33 months, anastrozole alone results in significant improvement in disease-free survival rates, reduction in contralateral breast cancers, and increased tolerability, compared to tamoxifen in postmenopausal women. Although the long-term effects of AIs are not known, the early positive results of the ATAC trial led to the approval of anastrozole by the US Food and Drug Administration for use as adjuvant hormonal therapy for postmenopausal women with hormone receptor-positive invasive breast cancer. Thus, there is an alternative to tamoxifen for postmenopausal women with relative/absolute contraindications to tamoxifen use or patients who choose not to take tamoxifen because of its side-effect profile. New AIs may challenge the position of tamoxifen as the gold standard for the treatment of early stage breast cancer in postmenopausal women.

Aromatase inhibitors for treatment of postmenopausal patients with breast cancer

The third generation of aromatase inhibitors and inactivators, such as anastrozole (Arimidex), letrozole (Femara) and exemestane (Aromasin), have become available for treatment of postmenopausal breast cancer patients. Several clinical trials have demonstrated that these new drugs can achieve better treatment results than megestrol acetate (Megace) and may replace tamoxifen for the first-line hormonal therapy for metastatic breast cancer patients. In fact, these drugs are now used in many hospitals and clinics for patients with metastatic breast cancer who were previously given tamoxifen as adjuvant treatment. However, the primary concern is whether they can be used as first-line agents for adjuvant treatment of primary breast cancer or are suitable for breast cancer prevention in view of possible adverse side effects. Recently, the Arimidex and Tamoxifen Alone or in Combination trial demonstrated the superiority in terms of disease-free survival of anastrozole over tamoxifen in adjuvant use for postmenopausal patients with Stage I and II primary breast cancer. The results of this report indicate the potential of anastrozole as an alternative drug in the adjuvant setting, although the mean follow-up time is so far only 47 months. Additional data regarding survival resulting from comparative trials of letrozole and tamoxifen and of exemestane and tamoxifen are expected to be available in a few years. However, limited information is available regarding adverse events caused by long-term administration of aromatase inhibitors. Longer follow-up is needed to determine the efficacy and safety of these new aromatase inhibitors when used for adjuvant treatment of postmenopausal patients with breast cancer.

Human epidermal growth factor receptor-2 and hormonal therapies: clinical implications

Estrogen-targeted therapies such as administration of tamoxifen or aromatase inhibitors are among the most important treatment strategies in the modern management of breast cancer. Despite initial responses in the metastatic setting and prolonged disease-free intervals in the adjuvant setting, many patients subsequently become resistant to these agents. Human epidermal growth factor receptor-2 (HER2) is a transmembrane glycoprotein receptor that is overexpressed in 13%-30% of human breast cancers. There are experimental data suggesting an important role for HER2 in de novo and acquired resistance to endocrine therapies. These experimental data are discussed in this article, as are clinical data addressing the role of HER2 in resistance to endocrine therapy in the adjuvant, neoadjuvant, and metastatic settings. Responses and benefit from tamoxifen appear to be impaired in patients in whom HER2 is overexpressed. In contrast, early data from the neoadjuvant setting suggest that responses to aromatase inhibitors may be maintained in patients with HER2 overexpression.

Anastrozole as adjuvant therapy for early-stage breast cancer: implications of the ATAC trial

Tamoxifen has been the gold standard adjuvant therapeutic agent for postmenopausal women with hormone-sensitive breast cancer for > 25 years. Although it continues to play an important role in treating premenopausal women, tamoxifen's association with some serious safety and tolerability issues, including increased incidence of endometrial cancer and thromboembolic events, may be cause to limit its use in postmenopausal women. Anastrozole was the first drug to show improved efficacy and safety compared with standard therapies for first- and second-line therapy of hormone-sensitive advanced breast cancer in postmenopausal women. This article provides a review of the results of the first major analysis of the Arimidex, Tamoxifen, Alone or in Combination (ATAC) early-stage breast cancer trial, initiated in 1996, and discusses the implications for the use of anastrozole in the adjuvant setting. This randomized, double-blind, multicenter trial compared tamoxifen (20 mg once daily) with anastrozole (1 mg) alone and in combination with tamoxifen, as adjuvant endocrine treatment for postmenopausal patients with operable, invasive, early-stage breast cancer. The results of the ATAC trial show anastrozole to be more effective and better tolerated than tamoxifen in this group of patients, and an updated follow-up suggests the therapeutic index for anastrozole will continue to remain superior to that of tamoxifen. Anastrozole is now emerging as a new standard for the adjuvant treatment of postmenopausal women with hormone-sensitive early-stage breast cancer. New adjuvant trials are currently using anastrozole in the control arm.