Randomised comparison of 5 years of adjuvant tamoxifen with continuous therapy for operable breast cancer. The Scottish Cancer Trials Breast Group

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.

Optimising adjuvant endocrine treatment of breast cancer with aromatase inhibitors

There is mounting evidence that aromatase inhibitors (AIs) are superior to tamoxifen as adjuvant treatment for postmenopausal women with oestrogen receptor positive breast cancer. Nevertheless, tamoxifen still remains a useful and relatively nontoxic treatment, and further work is necessary to determine which patients need an AI. In terms of cost-effectiveness, letrozole has been estimated to be superior to tamoxifen. Anastrozole, letrozole and exemestane have not been compared directly in an adjuvant setting but letrozole proved superior to anastrozole in patients with advanced breast cancer. Although tumour receptor phenotype may be useful in selection for tamoxifen or AI, the evidence is mixed. Optimal sequencing and duration of treatment have yet to be determined. If nationally funded and organised trials could be instigated, these would give timely and reliable data, so that adjuvant endocrine treatment of breast cancer could be tailored to needs of the individual patient.

The evolving role of aromatase inhibitors in adjuvant breast cancer therapy

The development of third-generation aromatase inhibitors (AIs) has brought about a major change in the therapeutic approach to patients with hormone-sensitive breast cancer. In randomized clinical trials, each of the third-generation AIs has demonstrated efficacy in the adjuvant treatment of postmenopausal women with receptor-positive tumors. Anastrozole has been shown to improve disease-free survival when compared with standard first-line tamoxifen, letrozole has been shown to further reduce the rate of breast cancer events when given as extended adjuvant therapy in women completing between 4.5 and 6 years of tamoxifen, and exemestane has been shown to improve disease-free survival when substituted for tamoxifen after an initial 2-3 years of adjuvant therapy. Although long-term follow-up for safety and overall survival continues in each of these trials, currently available data suggest that an AI should now be included as part of adjuvant endocrine therapy for the great majority of receptor-positive postmenopausal patients. To address these rapidly evolving issues related to the endocrine adjuvant treatment of postmenopausal women, an expert panel met in March 2004 in Hamburg, Germany, the site of the Fourth European Breast Cancer Conference. The panel's overview of recent endocrine data is presented along with updated results where available. In addition, case-based discussions are included to provide direction on how to integrate recent endocrine adjuvant clinical trial findings into everyday practice.

Adjuvant endocrine therapies for postmenopausal women with early breast cancer: Standards and not

Hormonal manipulations have been used for more than 100 years for the treatment of metastatic breast cancer and after definition of the concept of micro-metastases also in the adjuvant setting. In the postmenopausal population, tamoxifen has played the most important role for almost four decades. Progestins or the first generation of aromatase inhibitors (AIs) were only marginally used in the adjuvant setting due to their prohibitive toxicity. The new generation of anti-estrogen compounds, the selective estrogen receptor down-regulators (SERDs) like fulvestrant have a higher affinity for the estrogen receptor than tamoxifen, but none of its agonist activities, and have shown promising clinical activity in the treatment of advanced breast cancer. The third generation of AIs investigated in six large trials has been reported to be superior to tamoxifen in terms of disease-free survival, but not in terms of survival. These trials will be discussed in terms of results in different subpopulations and of toxicity.

Randomized trial of letrozole following tamoxifen as extended adjuvant therapy in receptor-positive breast cancer: updated findings from NCIC CTG MA.17

BACKGROUND

Most recurrences in women with breast cancer receiving 5 years of adjuvant tamoxifen occur after 5 years. The MA.17 trial, which was designed to determine whether extended adjuvant therapy with the aromatase inhibitor letrozole after tamoxifen reduces the risk of such late recurrences, was stopped early after an interim analysis showed that letrozole improved disease-free survival. This report presents updated findings from the trial.

METHODS

Postmenopausal women completing 5 years of tamoxifen treatment were randomly assigned to a planned 5 years of letrozole (n = 2593) or placebo (n = 2594). The primary endpoint was disease-free survival (DFS); secondary endpoints included distant disease-free survival, overall survival, incidence of contralateral tumors, and toxic effects. Survival was examined using Kaplan-Meier analysis and log-rank tests. Planned subgroup analyses included those by axillary lymph node status. All statistical tests were two-sided.

RESULTS

After a median follow-up of 30 months (range = 1.5-61.4 months), women in the letrozole arm had statistically significantly better DFS and distant DFS than women in the placebo arm (DFS: hazard ratio [HR] for recurrence or contralateral breast cancer = 0.58, 95% confidence interval [CI] = 0.45 to 0.76; P < .001; distant DFS: HR = 0.60, 95% CI = 0.43 to 0.84; P = .002). Overall survival was the same in both arms (HR for death from any cause = 0.82, 95% CI = 0.57 to 1.19; P = .3). However, among lymph node-positive patients, overall survival was statistically significantly improved with letrozole (HR = 0.61, 95% CI = 0.38 to 0.98; P = .04). The incidence of contralateral breast cancer was lower in women receiving letrozole, but the difference was not statistically significant. Women receiving letrozole experienced more hormonally related side effects than those receiving placebo, but the incidences of bone fractures and cardiovascular events were the same.

CONCLUSION

Letrozole after tamoxifen is well-tolerated and improves both disease-free and distant disease-free survival but not overall survival, except in node-positive patients.

Adjuvant endocrine therapy in postmenopausal women with early breast cancer: Where are we now?

Tamoxifen has been the standard of care for adjuvant endocrine therapy of early breast cancer. In postmenopausal women, data now suggest that alternative agents (aromatase inhibitors [AIs]) may have improved long-term risk:benefit profiles and thus have the potential to improve outcome. The 'Arimidex', Tamoxifen, alone or in combination (ATAC) trial has shown that anastrozole provides improved disease-free survival (DFS) and time to recurrence, significantly reduced time to distant metastases and superior overall tolerability compared with tamoxifen when used as initial adjuvant therapy. Results have already led to a reconsideration of current recommendations for adjuvant therapy. Other ongoing trials include studies that are evaluating the benefits of sequencing of endocrine agents both within the standard 5-year adjuvant treatment period and as additional therapy in the post-adjuvant period. Three recently reported trials have suggested that switching from tamoxifen to an AI after 2-3 years of treatment leads to better outcomes than 5 years of tamoxifen. Finally, the NCIC MA 17 trial has shown that switching to an AI after 5 years of tamoxifen improves DFS compared with placebo. These are momentous discoveries that have improved our biological understanding and will inevitably change the management of breast cancer in the near future.

Switching to anastrozole versus continued tamoxifen treatment of early breast cancer: preliminary results of the Italian Tamoxifen Anastrozole Trial

PURPOSE

Tamoxifen, which is actually the gold standard adjuvant treatment in estrogen receptor-positive early breast cancer, is associated with an increased risk of endometrial cancer and other life-threatening events. Moreover, many women relapse during or after tamoxifen therapy because of the development of resistance. Therefore new approaches are required.

PATIENTS AND METHODS

We conducted a prospective randomized trial to test the efficacy of switching postmenopausal patients who were already receiving tamoxifen to the aromatase inhibitor anastrozole. After 2 to 3 years of tamoxifen treatment, patients were randomly assigned either to receive anastrozole 1 mg/d or to continue receiving tamoxifen 20 mg/d, for a total duration of treatment of 5 years. Disease-free survival was the primary end point. Event-free survival, overall survival, and safety were secondary end points.

RESULTS

Four hundred forty-eight patients were enrolled. All women had node-positive, estrogen receptor-positive tumors. At a median follow-up time of 36 months, 45 events had been reported in the tamoxifen group compared with 17 events in the anastrozole group (P = .0002). Disease-free and local recurrence-free survival were also significantly longer in the anastrozole group (hazard ratio [HR] = 0.35; 95% CI, 0.18 to 0.68; P = .001 and HR = 0.15; 95% CI, 0.03 to 0.65; P = .003, respectively). Overall, more adverse events were recorded in the anastrozole group compared with the tamoxifen group (203 v 150, respectively; P = .04). However, more events were life threatening or required hospitalization in the tamoxifen group than in the anastrozole group (33 of 150 events v 28 of 203 events, P = .04).

CONCLUSION

Switching to anastrozole after the first 2 to 3 years of treatment is well tolerated and significantly improves event-free and recurrence-free survival in postmenopausal patients with early breast cancer.

Hormonal therapy for primary breast cancer: scientific rationale and status of clinical research

Endocrine therapies have played an important role in the management of breast cancer for many years. Tamoxifen had been the unchallenged standard in the adjuvant setting until recently. Data from recent clinical trials have emphasized the emerging roles of aromatase inhibitors and ovarian ablation in patients with early breast cancer. This review highlights previous data that led to the recognition of tamoxifen as the gold standard hormonal therapy in the adjuvant treatment of early breast cancer. We then discuss clinical trials demonstrating the impact of aromatase inhibitors as an alternative to tamoxifen or as a component of sequential treatment with tamoxifen in postmenopausal women with early breast cancer. Finally, we review data related to the incorporation of ovarian ablation into the treatment of early breast cancer in premenopausal women.

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.

Comparison of two-year and five-year tamoxifen use in Japanese post-menopausal women

AIM

Large multicenter, randomized trials have revealed the advantages of using tamoxifen for 5 years vs 2 years in breast cancer patients. The aim of this report is to confirm the optimal duration of tamoxifen administration in a study of Japanese breast cancer patients.

METHODS

Japanese post-menopausal estrogen receptor-positive breast cancer patients treated with mastectomy were randomly assigned to either a 5-year or 2-year course of tamoxifen. The primary endpoint was disease-free survival, with secondary endpoints of overall survival and a reduction in the development of metachronous contra-lateral breast cancer.

RESULTS

A total of 256 breast cancer patients were randomized to a 5-year or 2-year tamoxifen administration group. After a median follow-up time of 81 months, there were no significant differences seen in terms of disease-free or overall survival (p=0.65 and 0.56, respectively). Furthermore, the impact of the 5-year use of tamoxifen on the development of contra-lateral breast cancer did not reach statistical significance (p=0.0511). However, 5-year tamoxifen use was closely associated with gynaecological complications (p=0.0081).

CONCLUSION

We could not show a beneficial effect of using tamoxifen for 5 years over 2 years in Japanese estrogen receptor-positive patients. This is likely due to the small number of patients enrolled in our study; however, racial disparity may influence this result. A reevaluation is necessary to study the advantages of the 5-year use of tamoxifen in the Japanese racial subgroup.

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.

Lumpectomy plus tamoxifen with or without irradiation in women 70 years of age or older with early breast cancer

BACKGROUND

In women 70 years of age or older who have early breast cancer, it is unclear whether lumpectomy plus tamoxifen is as effective as lumpectomy followed by tamoxifen plus radiation therapy.

METHODS

Between July 1994 and February 1999, we randomly assigned 636 women who were 70 years of age or older and who had clinical stage I (T1N0M0 according to the tumor-node-metastasis classification), estrogen-receptor-positive breast carcinoma treated by lumpectomy to receive tamoxifen plus radiation therapy (317 women) or tamoxifen alone (319 women). Primary end points were the time to local or regional recurrence, the frequency of mastectomy for recurrence, breast-cancer-specific survival, the time to distant metastasis, and overall survival.

RESULTS

The only significant difference between the two groups was in the rate of local or regional recurrence at five years (1 percent in the group given tamoxifen plus irradiation and 4 percent in the group given tamoxifen alone, P<0.001). There were no significant differences between the two groups with regard to the rates of mastectomy for local recurrence, distant metastases, or five-year rates of overall survival (87 percent in the group given tamoxifen plus irradiation and 86 percent in the tamoxifen group, P=0.94). Assessment by physicians and patients of cosmetic results and adverse events uniformly rated tamoxifen plus irradiation inferior to tamoxifen alone.

CONCLUSIONS

Lumpectomy plus adjuvant therapy with tamoxifen alone is a realistic choice for the treatment of women 70 years of age or older who have early, estrogen-receptor-positive breast cancer.

Adjuvant endocrine therapy

Endocrine therapy remains a cornerstone of systemic therapy for breast cancer even though it was first introduced more than a century ago. In the past three decades a large number of randomized trials involving several tens of thousands of patients have been performed to determine the role of endocrine therapy in the adjuvant setting. The results of these studies indicate that hormonal therapy should be considered the standard adjuvant systemic treatment for the majority of patients with invasive breast cancer irrespective of age, menopausal status or tumour stage. This chapter aims to describe the "state of the art" relative to the use of adjuvant endocrine therapy with special focus on a number of salient issues, including: (i) the role of ovarian ablation and luteinising hormone releasing hormone (LHRH) analogues among pre-menopausal patients; (ii) optimal duration of tamoxifen; (iii) adjuvant therapy with third-generation, selective aromatase inhibitors; (iv) predictive biomarkers; (v) side-effects; (vi) combination endocrine therapy; (vii) future development of endocrine therapy.

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.

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.

Adjuvant systemic therapy of early stage breast cancer

Adjuvant chemotherapy reduces the risk of recurrence and mortality in patients with early stage breast cancer. Anthracycline-based regimens are the most widely used standard in the United States. The inclusion of the taxanes into adjuvant chemotherapy programs offers an improvement in disease-free survival rates and probably overall survival rates compared to an anthracycline-based regimen alone. Although adjuvant chemotherapy is effective in all age groups, the magnitude of benefit is greatest in younger premenopausal patients. Treatment decisions need to be individualized. Dose-dense chemotherapy approaches are promising and can be considered an option for patients with early stage breast cancer. Adjuvant tamoxifen therapy should be administered for 5 years in patients with hormone receptor-positive breast cancer. Adjuvant tamoxifen should be administered after the completion of adjuvant chemotherapy. Data from the ATAC (Arimidex, tamoxifen, alone, or in combination) trial provide a compelling argument for choosing anastrozole as adjuvant endocrine therapy in postmenopausal women with hormone receptor-positive early stage breast cancer. Long-term follow-up of patients is necessary to determine the effects of chronic aromatase inhibitor treatment on bone density, cognitive function, and other endpoints.

Tamoxifen ("Nolvadex"): a review

Tamoxifen has been used in the management of breast cancer for over 30 years. Since its introduction for the treatment of advanced breast cancer, its indications have increased to include the treatment of early breast cancer, ductal carcinoma in situ, and more recently for breast cancer chemoprevention. Tamoxifen has a good tolerability profile and moreover, unlike many other endocrine therapies, it is efficacious in both pre- and postmenopausal women. It is the combination of efficacy and tolerability that allows tamoxifen to maintain its position as the hormonal treatment of choice for most patients with oestrogen-receptor positive breast cancer. Ongoing studies will provide further information about the optimal duration of tamoxifen therapy and how it compares with the newer aromatase inhibitors.

Duration of adjuvant tamoxifen therapy

The benefit of using adjuvant tamoxifen to treat breast cancer has been firmly established for patients with estrogen receptor (ER)-positive tumors, regardless of age, lymph node status, or menopausal status. Uncertainty remains, however, regarding the optimal duration of tamoxifen therapy. We reviewed the findings of randomized clinical trials that directly compared alternative treatment durations. Trials comparing short-term adjuvant treatment with tamoxifen (i.e., 1-3 years) with treatments having durations of about 5 years consistently have demonstrated additional benefits stemming from the longer therapy. Trials testing 5 years of treatment with longer durations have, in the aggregate, suggested no additional benefit for the patient. Nevertheless, the number of recurrences reported to date in these trials is not large, and the results of the individual trials are heterogeneous. Furthermore, as a result of tamoxifen's "carryover" effect, duration trials require considerable follow-up before definitive results can be established. Until more definitive data become available, adjuvant treatment with tamoxifen should be limited to 5 years outside the clinical trials setting. Continued accrual of ER-positive patients to ongoing tamoxifen duration trials, including the Adjuvant Tamoxifen Treatment Offer More (aTTom) and Adjuvant Tamoxifen Longer Against Shorter (ATLAS) trials, is appropriate. Alternatively, patients who remain disease free after 5 years of tamoxifen therapy should be encouraged to participate in trials testing crossover to other hormonal interventions, including selective ER modulators or aromatase inhibitors.

Medical management of breast cancer: today and tomorrow

The medical management of invasive breast cancer has evolved based on the recognition that surgery alone was associated with few long-term cures. This Update will review the current status of breast cancer medical management in three areas: prevention in individuals with an elevated risk, adjuvant (postoperative) treatment of early breast cancer, and treatment principles in metastatic disease. Tamoxifen has emerged as a promising agent in the treatment of women at an increased risk for breast cancer and in those with in situ disease. However, the risks of treatment must be carefully weighed against the benefits in these cohorts of women with an excellent overall prognosis. This same principle can be applied to the use of adjuvant treatment in early invasive breast cancer, where the goal is cure. Adjuvant polychemotherapy is recommended in women considered at high-risk for relapse and death. In addition, women with hormone-sensitive breast cancer are offered adjuvant taxmoxifen. Nonetheless, there are some patients with low-risk disease or those with significant co-morbidities that are unlikely to benefit from adjuvant therapies and likely to sustain toxicities. The treatment goal in metastatic breast cancer is focused on palliation of symptoms as fewer than 10% of such patients achieve 5-year survival. However, novel targeted therapies are changing the treatment armamentarium and hold great promise. These new directions of treatment will be discussed as well as areas of controversy.

The value of adjuvant treatment in young women with breast cancer

The postoperative management of breast cancer is an ever-changing field. Young patients, in particular, have attracted recent interest as it has become apparent that age alone is a poor prognostic indicator for breast cancer. Adjuvant therapies indisputably delay breast cancer recurrence and save lives, and should be considered for all young patients. Chemotherapy is increasingly being considered appropriate for all women under the age of 35 years, regardless of other risk factors, but poses the particularly difficult problem of infertility for these young women. As the additional benefits of anthracyclines and taxanes in the adjuvant setting become clear, chemotherapy regimens are also becoming increasingly intensive and the risk of myocardial damage and leukaemia should not be ignored. The benefits of chemotherapy need to be weighed against the possible dangers, and therapy should be individualised according to cancer pathology and patient circumstance. Tamoxifen should be given for 5 years to all women whose cancer is estrogen receptor positive, regardless of whether the patient has received chemotherapy. If chemotherapy is not given, the addition of luteinising hormone-releasing hormone (LHRH) agonists to tamoxifen in patients with estrogen receptor positive breast cancers appears to be beneficial. The addition of LHRH agonists to chemotherapy and tamoxifen is currently being evaluated in randomised trials. Radiotherapy should be given after breast conservation surgery, and should include the axilla if nodes are involved and the axilla has not been surgically cleared. Chest wall radiotherapy should be considered following mastectomy in young women considered at high risk of local recurrence, but the long-term morbidity and mortality of local radiation therapy, which is increased in young women, needs to be considered.

Adjuvant therapy for breast cancer--results from the USA consensus conference

The National Institutes of Health, USA sponsored a Consensus Development Conference on November 1-3, 2000 to review several major questions regarding the adjuvant treatment of breast cancer. A non-governmental group of oncology experts was selected to review clinical trial data and judge the evidence presented by 33 breast cancer researchers. Their conclusions resulted in the following recommendations: (1) Prognostic factors critical for determining risk of recurrence are age, axillary lymph node status, tumor size, histologic type and grade and hormone receptor status. (2) Tamoxifen, administered for 5 years, significantly improves long-term survival for women of all age groups with hormone receptor-positive tumors. Ovarian ablation also prolongs survival in premenopausal women. (3) Multi-agent chemotherapy of 4-6 months duration is associated with an improvement in survival in both hormone receptor-positive and -negative tumors. Anthracycline-containing regimens offer the greatest survival advantage. The role of taxanes is uncertain but they may be useful in selected patients with node-positive tumors. Women with small, node-negative tumors, women over age 70, and those with tumors of favorable histologic subtype (mucinous or tubular) may not require chemotherapy. (4) Adjuvant radiotherapy to the regional lymph nodes and chest wall following mastectomy is indicated for women with 4 or more axillary nodes. (5) Physicians should employ effective visual aids to help them present a complete and balanced view of the absolute benefits versus the side-effects of adjuvant treatments. Important avenues of future research were also discussed and suggestions were made.

Adaptive hypersensitivity to estradiol: potential mechanism for secondary hormonal responses in breast cancer patients

Women with hormone dependent breast cancer initially respond to hormone deprivation therapy with tamoxifen or oophorectomy for 12-18 months but later relapse. Upon secondary therapy with aromatase inhibitors, patients often experience further tumor regression. The mechanisms responsible for secondary responses are unknown. We postulated that hormone deprivation induces hypersensitivity to estradiol. Evidence of this phenomenon was provided in a model system involving MCF-7 cells grown in vitro and in xenografts. To determine if the ER transcriptional process is involved in hypersensitivity, we examined the effect of estradiol on ER reporter activity, PgR, PS2, and c-myc as markers and found no alterations in hypersensitive cells. Next, we examined whether MAP kinase may be upregulated in the hypersensitive cells as a reflection of increased growth factor secretion or action. Basal MAP kinase activity was increased both in vitro and in vivo in hypersensitive cells. Proof of principle studies indicated that an increase in MAP kinase activity induced by TGFalpha administration caused a two- to three-fold shift to the left in estradiol dose response curves in wild type cells. Blockade of MAP kinase with PD98059 returned the shifted curve back to baseline. These data suggested that MAP kinase overexpression could induce hypersensitivity. To determine why MAP kinase was increased, we excluded constitutive receptor activity and growth factor secretion by the demonstration that the pure anti-estrogen, ICI 182780, could inhibit MAP kinase activation. We also excluded hypersensitivity to estradiol induced growth factor secretion, and thus MAP kinase activation, since estradiol stimulated MAP kinase at 24, 48, and 72 h at the same concentrations in hypersensitive as in wild type cells. Surprisingly, a series of experiments suggested that MAP kinase increased in hypersensitive cells as a result of estrogen activation via a non-genomic pathway. We examined the classical signal pathway in which SHC is phosphorylated and binds to SOS and GRB-2 to activate Ras, Raf, and MAP kinase. With 5-20 min of exposure, estradiol caused binding of SHC to the estrogen receptor, phosphorylation of SHC, binding of GRB-2 to SOS, and activation of MAP kinase. All of these affects could be blocked by ICI 182780. Taken together, these observations suggest that the cell membrane ER pathway may be responsible for upregulation of MAP kinase and hypersensitivity in cells adapted to estradiol deprivation.

Use of SERMs for the adjuvant therapy of early-stage breast cancer

Tamoxifen was the first in a class of drugs now commonly referred to as selective estrogen receptor modulators or SERMs. SERMs exhibit tissue-specific estrogenic agonist/antagonist activity through their ability to bind to the estrogen receptor alpha (ER) protein and interact with coregulatory proteins, thereby modulating transcription of estrogen target genes. Since its first approval by the United States Food and Drug Administration (FDA) in 1977, tamoxifen has been found to (a) lower the risk of recurrence and death for women with early-stage hormone receptor-positive breast cancer, irrespective of menopausal and node status or use of adjuvant chemotherapy; (b) reduce the risk of invasive breast cancer following breast conservation in women with ductal carcinoma in situ (DCIS); and (c) reduce the risk of breast cancer in high-risk women. Toremifene is the only other SERM approved by the FDA for breast cancer treatment. However, it offers no clear clinical advantage over tamoxifen in the adjuvant or metastatic settings. Several other SERMs are in various phases of clinical development. In addition, strategies to combine SERMs with other endocrine therapy like ovarian suppression or aromatase inhibitors are active areas of investigations. At present, SERMs are recognized as the first targeted and relatively nontoxic medical therapy for women with high-risk or steroid hormone receptor-positive breast cancer.

National Institutes of Health Consensus Development Conference Statement: adjuvant therapy for breast cancer, November 1-3, 2000

OBJECTIVE

Our goal was to provide health-care providers, patients, and the general public with an assessment of currently available data regarding the use of adjuvant therapy for breast cancer.

PARTICIPANTS

The participants included a non-Federal, non-advocate, 14-member panel representing the fields of oncology, radiology, surgery, pathology, statistics, public health, and health policy as well as patient representatives. In addition, 30 experts in medical oncology, radiation oncology, biostatistics, epidemiology, surgical oncology, and clinical trials presented data to the panel and to a conference audience of 1000.

EVIDENCE

The literature was searched with the use of MEDLINE(TM) for January 1995 through July 2000, and an extensive bibliography of 2230 references was provided to the panel. Experts prepared abstracts for their conference presentations with relevant citations from the literature. Evidence from randomized clinical trials and evidence from prospective studies were given precedence over clinical anecdotal experience.

CONSENSUS PROCESS

The panel, answering predefined questions, developed its conclusions based on the evidence presented in open forum and the scientific literature. The panel composed a draft statement, which was read in its entirety and circulated to the experts and the audience for comment. Thereafter, the panel resolved conflicting recommendations and released a revised statement at the end of the conference. The panel finalized the revisions within a few weeks after the conference. The draft statement was made available on the World Wide Web immediately after its release at the conference and was updated with the panel's final revisions. The statement is available at http://consensus.nih.gov.

CONCLUSIONS

The panel concludes that decisions regarding adjuvant hormonal therapy should be based on the presence of hormone receptor protein in tumor tissues. Adjuvant hormonal therapy should be offered only to women whose tumors express hormone receptor protein. Because adjuvant polychemotherapy improves survival, it should be recommended to the majority of women with localized breast cancer regardless of lymph node, menopausal, or hormone receptor status. The inclusion of anthracyclines in adjuvant chemotherapy regimens produces a small but statistically significant improvement in survival over non-anthracycline-containing regimens. Available data are currently inconclusive regarding the use of taxanes in adjuvant treatment of lymph node-positive breast cancer. The use of adjuvant dose-intensive chemotherapy regimens in high-risk breast cancer and of taxanes in lymph node-negative breast cancer should be restricted to randomized trials. Ongoing studies evaluating these treatment strategies should be supported to determine if such strategies have a role in adjuvant treatment. Studies to date have included few patients older than 70 years. There is a critical need for trials to evaluate the role of adjuvant chemotherapy in these women. There is evidence that women with a high risk of locoregional tumor recurrence after mastectomy benefit from postoperative radiotherapy. This high-risk group includes women with four or more positive lymph nodes or an advanced primary cancer. Currently, the role of postmastectomy radiotherapy for patients with one to three positive lymph nodes remains uncertain and should be tested in a randomized controlled trial. Individual patients differ in the importance they place on the risks and benefits of adjuvant treatments. Quality of life needs to be evaluated in selected randomized clinical trials to examine the impact of the major acute and long-term side effects of adjuvant treatments, particularly premature menopause, weight gain, mild memory loss, and fatigue. Methods to support shared decision-making between patients and their physicians have been successful in trials; they need to be tailored for diverse populations and should be tested for broader dissemination.

Five versus more than five years of tamoxifen for lymph node-negative breast cancer: updated findings from the National Surgical Adjuvant Breast and Bowel Project B-14 randomized trial

BACKGROUND

Previously reported information from B-14, a National Surgical Adjuvant Breast and Bowel Project (NSABP) randomized, placebo-controlled clinical trial, demonstrated that patients with estrogen receptor (ER)-positive breast cancer and negative axillary lymph nodes experienced a prolonged benefit from 5 years of tamoxifen therapy. When these women were rerandomized to receive either placebo or more prolonged tamoxifen therapy, they obtained no additional advantage from tamoxifen through 4 years of follow-up. Because the optimal duration of tamoxifen administration continues to be controversial and because there have been 3 more years of follow-up and a substantial increase in the number of events since our last report, an update of the B-14 study is appropriate.

METHODS

Patients (n = 1172) who had completed 5 years of tamoxifen therapy and who were disease free were rerandomized to receive placebo (n = 579) or tamoxifen (n = 593). Survival, disease-free survival (DFS), and relapse-free survival (RFS) were estimated by the Kaplan-Meier method; the differences between the treatment groups were assessed by the log-rank test. Relative risks of failure (with 95% confidence intervals) were determined by the Cox proportional hazards model. P values were two-sided.

RESULTS

Through 7 years after reassignment of tamoxifen-treated patients to either placebo or continued tamoxifen therapy, a slight advantage was observed in patients who discontinued tamoxifen relative to those who continued to receive it: DFS = 82% versus 78% (P =.03), RFS = 94% versus 92% (P =.13), and survival = 94% versus 91% (P =.07), respectively. The lack of benefit from additional tamoxifen therapy was independent of age or other characteristics.

CONCLUSION

Through 7 years of follow-up after rerandomization, there continues to be no additional benefit from tamoxifen administered beyond 5 years in women with ER-positive breast cancer and negative axillary lymph nodes.

Prospective study on gynaecological effects of two antioestrogens tamoxifen and toremifene in postmenopausal women

To assess and compare the gynaecological consequences of the use of 2 antioestrogens we examined 167 postmenopausal breast cancer patients before and during the use of either tamoxifen (20 mg/day, n = 84) or toremifene (40 mg/day, n = 83) as an adjuvant treatment of stage II-III breast cancer. Detailed interview concerning menopausal symptoms, pelvic examination including transvaginal sonography (TVS) and collection of endometrial sample were performed at baseline and at 6, 12, 24 and 36 months of treatment. In a subgroup of 30 women (15 using tamoxifen and 15 toremifene) pulsatility index (PI) in an uterine artery was measured before and at 6 and 12 months of treatment. The mean (+/-SD) follow-up time was 2.3 +/- 0.8 years. 35% of the patients complained of vasomotor symptoms before the start of the trial. This rate increased to 60.0% during the first year of the trial, being similar among patients using tamoxifen (57.1%) and toremifene (62.7%). Vaginal dryness, which was present in 6.0% at baseline, increased during the use of tamoxifen (26.2%) and toremifene (24.1%). Endometrial thickness increased from baseline (3.9 +/- 2.7 mm) to 6.8 +/- 4.2 mm at 6 months (P< 0.001), and no difference emerged between the 2 regimens in this regard. Before the start of the antioestrogen regimen, the endometrium was atrophic in 71 (75.5%) and proliferative in 19 of 94 (20.2%) samples; 4 patients had benign endometrial polyps. During the use of antioestrogen altogether 339 endometrial samples were taken (159 in tamoxifen group, 180 in toremifene group). The endometrium was proliferative more often in the tamoxifen group (47.8%) than in the toremifene group (32.2%) (P< 0.0001). 20 patients had a total of 24 polyps (17 in tamoxifen and 9 in toremifene group, P< 0.05) during the use of antioestrogens. One patient in the toremifene group developed endometrial adenocarcinoma at 12 months, and one patient had breast cancer metastasis on the endometrium. Tamoxifen failed to affect the PI in the uterine artery, but toremifene reduced it by 15.0% (P< 0.05) by 12 months. In conclusion, tamoxifen and toremifene cause similarly vasomotor and vaginal symptoms. Neither regimen led to the development of premalignant endometrial changes. Our data suggest that so close endometrial surveillance as used in our study may not be mandatory during the first 3 years of use of antioestrogen treatment.

Operable breast cancer

Breast cancer is the most common malignancy among American women. As a result of widespread screening, most patients present with operable breast cancer that is treated with curative intent. It is well established that the appropriate use of adjuvant therapy improves the disease-free and overall survival of patients with breast cancer. Adjuvant systemic therapy options include tamoxifen for hormone receptor-positive patients, and systemic polychemotherapy. It is standard clinical practice to administer adjuvant systemic therapy to patients with node-positive and high-risk, node-negative breast cancer.

Scottish adjuvant tamoxifen trial: a randomized study updated to 15 years

BACKGROUND AND METHODS

The Scottish Adjuvant Tamoxifen Trial (main trial) was initiated in April 1978 to assess the effect of tamoxifen given to patients with breast cancer immediately after mastectomy (or mastectomy plus radiation therapy) (adjuvant arm) or only after the patients had had a relapse (control arm); 1323 patients were randomly assigned (667 to the adjuvant arm and 656 to the control arm). Results have been reported for the follow-up period from 2.5 through 8 years. In this article, we report updated results after a median follow-up of 15 years. If agreeable and eligible, patients who were disease free at 5 years in the adjuvant arm of the main trial were entered into a duration trial and randomly assigned either to stop taking tamoxifen (169 patients) or to continue taking it indefinitely until relapse or death (173 patients). For this update, we analyzed information on death, recurrence, survival, and other malignancies for all but 21 of the 560 living patients from the original and duration trials to determine the probabilities of total survival, systemic relapse of disease, and death from breast cancer. All statistical tests are two-sided.

RESULTS

The beneficial effect of adjuvant tamoxifen given for 5 years on the probability of total survival (P =.006), systemic relapse (P =.007), and death from breast cancer (P =.002) has been maintained through 15 years. No additional benefit was observed in those randomly assigned to continue taking tamoxifen beyond 5 years.

CONCLUSION

Information from this study suggests that, if adjuvant tamoxifen is given to women with operable breast cancer, it need not be for more than 5 years.

Tamoxifen for early breast cancer

BACKGROUND

There have been many randomised trials of adjuvant tamoxifen among women with early breast cancer, and an updated overview of their results is presented.

OBJECTIVES

In this report, the Early Breast Cancer Trialists' Collaborative Group present their third 5-yearly systematic overview (meta-analysis) of treatment with tamoxifen.

SEARCH STRATEGY

Trial identification procedures for the EBCTCG overviews have been described elsewhere. See under "EBCTCG" in the Breast Cancer Collaborative Review Group module.

SELECTION CRITERIA

All randomised trials that began before 1990 and compared adjuvant tamoxifen for any duration versus no such treatment for women with early breast cancer.

DATA COLLECTION AND ANALYSIS

In 1995, information was sought on each woman in any randomised trial that began before 1990 of adjuvant tamoxifen versus no tamoxifen before recurrence. Information was obtained and analysed centrally on each of 37,000 women in 55 such trials, comprising about 87% of the worldwide evidence. Compared with the previous such overview, this approximately doubles the amount of evidence from trials of about 5 years of tamoxifen and, taking all trials together, on events occurring more than 5 years after randomisation.

MAIN RESULTS

Nearly 8000 of the women had a low, or zero, level of the oestrogen-receptor protein (ER) measured in their primary tumour. Among them, the overall effects of tamoxifen appeared to be small, and subsequent analyses of recurrence and total mortality are restricted to the remaining women (18,000 with ER-positive tumours, plus nearly 12,000 more with untested tumours, of which an estimated 8000 would have been ER-positive). For trials of 1 year, 2 years, and about 5 years of adjuvant tamoxifen, the proportional recurrence reductions produced among these 30,000 women during about 10 years of follow-up were 21% (SD 3), 29% (SD 2), and 47% (SD 3), respectively, with a highly significant trend towards greater effect with longer treatment (2p<0.00001). The corresponding proportional mortality reductions were 12% (SD 3), 17% (SD 3), and 26% (SD 4), respectively, and again the test for trend was significant (2p=0.003). The absolute improvement in recurrence was greater during the first 5 years, whereas the improvement in survival grew steadily larger throughout the first 10 years. The proportional mortality reductions were similar for women with node-positive and node-negative disease, but the absolute mortality reductions were greater in node-positive women. In the trials of about 5 years of adjuvant tamoxifen the absolute improvements in 10-year survival were 10.9% (SD 2.5) for node-positive (61.4% vs 50.5% survival, 2p<0.00001) and 5.6% (SD 1.3) for node-negative (78.9% vs 73.3% survival, 2p<0.00001). These benefits appeared to be largely irrespective of age, menopausal status, daily tamoxifen dose (which was generally 20 mg), and of whether chemotherapy had been given to both groups. In terms of other outcomes among all women studied (ie, including those with "ER-poor" tumours), the proportional reductions in contralateral breast cancer were 13% (SD 13), 26% (SD 9), and 47% (SD 9) in the trials of 1, 2, or about 5 years of adjuvant tamoxifen. The incidence of endometrial cancer was approximately doubled in trials of 1 or 2 years of tamoxifen and approximately quadrupled in trials of 5 years of tamoxifen (although the number of cases was small and these ratios were not significantly different from each other). The absolute decrease in contralateral breast cancer was about twice as large as the absolute increase in the incidence of endometrial cancer. Tamoxifen had no apparent effect on the incidence of colorectal cancer or, after exclusion of deaths from breast or endometrial cancer, on any of the other main categories of cause of death (total nearly 2000 such deaths; overall relative risk 0.99 [SD 0.05]).

REVIEWER'S CONCLUSIONS

For women with tumours that have been reliably shown to be ER-negative, adjuvant tamoxifen remains a matter for research. However, some years of adjuvant tamoxifen treatment substantially improves the 10-year survival of women with ER-positive tumours and of women whose tumours are of unknown ER status, with the proportional reductions in breast cancer recurrence and in mortality appearing to be largely unaffected by other patient characteristics or treatments.

Second cancers after adjuvant tamoxifen therapy for breast cancer in Japan

BACKGROUND

Women treated with tamoxifen for breast cancer are at increased risk of endometrial cancer. We conducted a retrospective cohort study to evaluate the risk of second primary cancers after adjuvant tamoxifen therapy for breast cancer in Japan.

PATIENTS AND METHODS

The subjects of the study were 6148 women who had been diagnosed with stage I, II, or IIIA unilateral primary breast cancer and had received surgical treatment during the period from January 1982 through December 1990 at nine institutions in Japan. The information on each patient was obtained from medical records or a prospectively compiled computer database at each institution.

RESULTS

Of the 6148 women, 3588 (58.4%) were administered tamoxifen as an adjuvant treatment and 2560 (41.6%) were not administered. Median follow-up periods were 7.64 years for tamoxifen-treated patients and 8.10 years for non-tamoxifen-treated patients, respectively. The duration of tamoxifen treatment was mostly two years or less (80.7%), and few patients received tamoxifen for more than five years. The cumulative incidence rates of all second cancers at 10 years were 4.61% and 4.09% among tamoxifen-treated and non-tamoxifen-treated patients (P = 0.62), respectively, and the incidence rate ratio (IRR) for all second cancers was 1.06 (95% confidence interval (CI): 0.77-1.47) after adjustment of several covariates. The numbers of endometrial cancers was 9 and 3 among tamoxifen-treated and non-tamoxifen-treated patients, respectively, and the IRR was 2.37 (95% CI: 0.64-8.77, P = 0.20). Of the 12 patients who developed endometrial cancer, 4 died of cancer (for 3 of them, the cause of death was breast cancer), and the other 8 patients were alive as of March 1996. Stomach cancer was the most frequent second cancer and the IRR was 1.34 (95% CI: 0.76-2.38, P = 0.31). There was no substantial increase in any other type of gastrointestinal cancer such as colorectal and liver cancers among tamoxifen-treated patients.

CONCLUSIONS

The incidence and risk of second primary cancers associated with tamoxifen therapy is low. The potential benefit of adjuvant tamoxifen therapy in breast cancer patients outweighs the risk of second primary cancers for Japanese breast cancer patients.

Safety and efficacy results of a randomized trial comparing adjuvant toremifene and tamoxifen in postmenopausal patients with node-positive breast cancer. Finnish Breast Cancer Group

PURPOSE

In this multicenter trial, toremifene 40 mg/d was compared with tamoxifen 20 mg/d, both given orally for 3 years to postmenopausal, axillary node-positive women after breast surgery.

PATIENTS AND METHODS

The first 899 patients (toremifene, n = 459; tamoxifen, n = 440) of the total of 1,480 patients accrued to the trial were included in this scheduled safety analysis. The mean follow-up time was 3.4 years.

RESULTS

The two treatment groups were well balanced with respect to patient and disease characteristics. The subjective side-effect profile was similar in both treatment groups. Slightly more vascular complications (deep vein thromboses, cerebrovascular events, and pulmonary embolisms) were seen among tamoxifen-treated patients (5.9%) as compared with toremifene-treated patients (3.5%) (P: =.11), whereas bone fractures (P: =.09) and vaginal leukorrhea (P: =.05) were more common in the toremifene group. The number of subsequent second cancers was similar. The breast cancer recurrence rate was 23.1% (n = 106) in the toremifene group and 26.1% (n = 115) in the tamoxifen group (P: =.31). When only patients with estrogen receptor (ER)-positive cancer were considered (n = 556), the risk for breast cancer recurrence was nonsignificantly lower among the toremifene-treated women, with a hazards ratio of 0.74 (90% confidence interval, 0.52 to 1.04; P: =.14). The mean time to breast cancer recurrence and overall survival were similar in both groups.

CONCLUSION

The side-effect profile of toremifene resembles that of tamoxifen. The efficacy of toremifene seems to be no less than that of tamoxifen. The trend for fewer breast cancer recurrences in the ER-positive subgroup is encouraging, but a longer follow-up is needed to confirm this.

Tamoxifen adjuvant treatment duration in early breast cancer: initial results of a randomized study comparing short-term treatment with long-term treatment. Fédération Nationale des Centres de Lutte Contre le Cancer Breast Group

PURPOSE

In 1986, The Fédération Nationale desCentres de Lutte Contre le Cancer Breast Group initiated a multicenter randomized trial to assess the usefulness of long-term adjuvant tamoxifen treatment. Short-term adjuvant tamoxifen treatment was to be compared with life long adjuvant tamoxifen treatment.

PATIENTS AND METHODS

Patients who were disease-free after 2 to 3 years of adjuvant tamoxifen treatment were eligible for the trial. From September 1986 to May 1995, 3,793 patients were randomized from France, Belgium, and Argentina. A total of 1,882 patients stopped tamoxifen (short-term group), and 1,911 patients were to continue tamoxifen for life (long-term group) at the same dose as previously prescribed. The protocol was modified in February 1997, limiting tamoxifen treatment to 10 years after randomization, thus giving a comparison between a 2- to 3-year treatment and a 12- to 13-year treatment. To date, the median duration of tamoxifen treatment is 30 months in the short-term group, and 70 months in the long-term group.

RESULTS

Overall, longer tamoxifen treatment induced a 23% reduction in relapse rates, leading to a 7-year disease-free survival rate of 78%, compared with 72% in the shorter-treatment group. In contrast, overall survival did not differ between the two groups, with a 79% overall survival rate in both groups. This improvement in disease-free survival could be observed in node-positive patients (P: =.001); however, it was not found in node-negative patients. Prolonged tamoxifen treatment corresponded to a significant increase in disease-free survival in estrogen receptor-positive patients (P: =.03) as well as in estrogen receptor-negative patients (P: =.05). Furthermore, longer treatment reduced contralateral breast cancers and did not increase the number of endometrial cancers.

CONCLUSION

Although no survival advantage was noted, patients did benefit from longer tamoxifen treatment over 3 years and had significantly better disease-free survival compared with patients who stopped hormonal treatment. Long-term follow-up is needed to assess these results. Most patients in the long-term group are still receiving treatment. Comparison of results as time passes will enable conclusions to be made on the value of long-term treatment over 5 years compared with 2 to 3 years.

Antiaromatase agents after adjuvant tamoxifen: rationale and clinical implications

Although tamoxifen is considered standard adjuvant hormonal therapy in receptor-positive, stage I and II breast cancer, information on its optimal duration of administration has only been reported recently and, for many, the subject is still a matter of scientific debate. Data suggest that there is a time period beyond which, if tamoxifen is continued, it may become ineffective or even detrimental to the patient. Tamoxifen is usually discontinued after approximately 5 years of therapy, at which time most patients are thought to be disease free; however, some patients may harbor residual micrometastases. A fraction of these patients will have micrometastatic tumor cells that are still responsive to tamoxifen, and tamoxifen discontinuation could result in cancer cell growth. The preponderance of clinical data, however, indicate that a greater fraction of patients will have micrometastatic tumor cells that have become progressively resistant to tamoxifen. In fact, tumor cell growth could be stimulated by continued therapy with the drug. Although in some patients the micrometastatic tumor cells may have become hormonally unresponsive, in most cases (tamoxifen-responsive or tamoxifen-stimulated micrometastases), the tumor remains hormonally responsive. Therefore, the use of anti-aromatase agents to reduce the level of estrogenic stimulation and, as a result, the risk of recurrence may prove to be a valuable approach at the time of tamoxifen discontinuation. The National Surgical Adjuvant Breast and Bowel Project (NSABP) is in the final stages of developing a clinical trial (NSABP B-33) to evaluate the effect of administering 2 years of therapy with the aromatase inactivator exemestane to postmenopausal, receptor-positive patients who have completed 5 years of tamoxifen therapy and are disease free at the time of tamoxifen discontinuation.

Selective estrogen receptor modulators: structure, function, and clinical use

The sex hormone estrogen is important for many physiologic processes. Prolonged stimulation of breast ductal epithelium by estrogen, however, can contribute to the development and progression of breast cancer, and treatments designed to block estrogen's effects are important options in the clinic. Tamoxifen and other similar drugs are effective in breast cancer prevention and treatment by inhibiting the proliferative effects of estrogen that are mediated through the estrogen receptor (ER). However, these drugs also have many estrogenic effects depending on the tissue and gene, and they are more appropriately called selective estrogen receptor modulators (SERMs). SERMs bind ER, alter receptor conformation, and facilitate binding of coregulatory proteins that activate or repress transcriptional activation of estrogen target genes. Theoretically, SERMs could be synthesized that would exhibit nearly complete agonist activity on the one hand or pure antiestrogenic activity on the other. Depending on their functional activities, SERMs could then be developed for a variety of clinical uses, including prevention and treatment of osteoporosis, treatment and prevention of estrogen-regulated malignancies, and even for hormone replacement therapy. Tamoxifen is effective in patients with ER-positive metastatic breast cancer and in the adjuvant setting. The promising role for tamoxifen in ductal carcinoma-in-situ or for breast cancer prevention is evolving, and its use can be considered in certain patient groups. Other SERMs are in development, with the goal of reducing toxicity and/or improving efficacy, and future agents have the potential of providing a new paradigm for maintaining the health of women.

Current status of tamoxifen use: An update for the surgical oncologist

The surgical oncologist is frequently responsible for the screening and diagnosis of women with breast cancer. In this pivotal role, they are often the first to discuss treatment options, including nonsurgical interventions, with breast cancer patients. Recent long-term clinical trial data provide support for the use of tamoxifen to prevent breast cancer in women at high risk of the disease. A breast cancer risk assessment can help identify women at higher than average risk for the disease, who may be appropriate candidates for chemoprevention. It is important for the surgical oncologist to understand the current indications and evidence regarding the use of tamoxifen for breast cancer prevention and treatment as they counsel their patients on available options.