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

Insights adjusting for non-adherence in randomized clinical trials: a reanalysis of an adjuvant trial of tamoxifen duration in early breast cancer

BACKGROUND

Several randomized clinical trials provide evidence of the survival benefit of extended adjuvant tamoxifen in women with estrogen receptor (ER)-positive early breast cancer (BC). However, non-adherence may lead to underestimate treatment effects using intention to treat (ITT) methods. We reanalyzed a randomized trial using contemporary statistical methods adjusting for non-adherence.

METHODS

The TAM01 study was a phase 3 trial including women with early BC, who had completed 2-3 years of adjuvant tamoxifen between 1986 and 1995. Participants were randomly assigned to continue tamoxifen up to 10 years or to discontinue the treatment at randomization. Invasive disease-free survival (iDFS) and overall survival (OS) were estimated using marginal structural models (MSM) and rank preserving structural failure time model (RPSFTM).

RESULTS

Of 3830 patients enrolled, 2485 were randomized to extended tamoxifen, and 1345 to treatment discontinuation. The 10-year non-adherence rate in the extended group was 27.2%. Among women with ER-positive BC (n = 2402), extended tamoxifen was associated with a 45% and 21% relative improvement in iDFS by MSM and RPSFTM, respectively (Hazard Ratio (HR), 0.55; 95% Confidence Interval (CI), 0.48-0.64 and HR, 0.79; 95%CI, 0.67-0.95, respectively), a considerable greater benefit than in the ITT analysis (HR, 0.90; 95%CI, 0.81-0.99). The OS reanalysis revealed a substantial benefit of extended tamoxifen (MSM: HR, 0.70; 95%CI, 0.59-0.83; RPSFTM: HR, 0.85; 95%CI, 0.67-1.04), compared to the ITT analyses (HR, 0.94; 95%CI, 0.84-1.07).

CONCLUSION

This analysis emphasizes both the importance of adherence to hormonotherapy in hormone-receptor positive early BC and the usefulness of more complex statistical analyses.

Overcoming oncogene addiction in breast and prostate cancers: a comparative mechanistic overview

Prostate cancer (PCa) and breast cancer (BCa) are both hormone-dependent cancers that require the androgen receptor (AR) and estrogen receptor (ER, ESR1) for growth and proliferation, respectively. Endocrine therapies that target these nuclear receptors (NRs) provide significant clinical benefit for metastatic patients. However, these therapeutic strategies are seldom curative and therapy resistance is prevalent. Because the vast majority of therapy-resistant PCa and BCa remain dependent on the augmented activity of their primary NR driver, common mechanisms of resistance involve enhanced NR signaling through overexpression, mutation, or alternative splicing of the receptor, coregulator alterations, and increased intracrine hormonal synthesis. In addition, a significant subset of endocrine therapy-resistant tumors become independent of their primary NR and switch to alternative NR or transcriptional drivers. While these hormone-dependent cancers generally employ similar mechanisms of endocrine therapy resistance, distinct differences between the two tumor types have been observed. In this review, we compare and contrast the most frequent mechanisms of antiandrogen and antiestrogen resistance, and provide potential therapeutic strategies for targeting both advanced PCa and BCa.

[Desire for pregnancy and breast cancer]

Breast cancer affects about 3,000 new women of childbearing age each year. The desire for pregnancy is therefore a frequent issue in the management of breast cancer. We reviewed the current state of knowledge and recommendations in high-risk women, on the consideration of this desire for pregnancy in therapeutic management, the way to approach it, the preservation of fertility in the care process and finally on the outcomes of pregnancy after breast cancer. We evaluated the desire for pregnancy, qualitatively and quantitatively, after breast cancer through a literature review.

Targeting of EGFR, VEGFR2, and Akt by Engineered Dual Drug Encapsulated Mesoporous Silica-Gold Nanoclusters Sensitizes Tamoxifen-Resistant Breast Cancer

Tamoxifen administration enhanced overall disease-free survival and diminished mortality rates in cancer patients. However, patients with breast cancer often fail to respond for tamoxifen therapy due to the development of a drug-resistant phenotype. Functional analysis and molecular studies suggest that protein mutation and dysregulation of survival signaling molecules such as epidermal growth factor receptor, vascular endothelial growth factor receptor 2, and Akt contribute to tamoxifen resistance. Various strategies, including combinatorial therapies, show chemosensitize tamoxifen-resistant cancers. Based on chemotoxicity issues, researchers are actively investigating alternative therapeutic strategies. In the current study, we fabricate a mesoporous silica gold cluster nanodrug delivery system that displays exceptional tumor-targeting capability, thus promoting accretion of drug indices at the tumor site. We employ dual drugs, ZD6474, and epigallocatechin gallate (EGCG) that inhibit EGFR2, VEGFR2, and Akt signaling pathways since changes in these signaling pathways confer tamoxifen resistance in MCF 7 and T-47D cells. Mesoporous silica gold cluster nanodrug delivery of ZD6474 and EGCG sensitize tamoxifen-resistant cells to apoptosis. Western and immune-histochemical analyses confirmed the apoptotic inducing properties of the nanoformulation. Overall, results with these silica gold nanoclusters suggest that they may be a potent nanoformulation against chemoresistant cancers.

Adjuvant endocrine monotherapy for postmenopausal early breast cancer patients with hormone-receptor positive: a systemic review and network meta-analysis

BACKGROUND

In patients with hormone receptor-positive postmenopausal of early stage breast cancer, adjuvant endocrine monotherapies include letrozole, anastrozole, exemestane, toremifene and tamoxifen. But the optimum regimen remains controversial.

METHODS

PubMed, Cochrane Database and ClinicalTrials.gov were systematically reviewed of abstract for randomized-controlled trials (RCTs) to assess the efficacy of tamoxifen, letrozole, exemestane, anastrozle and toremifene for postmenopausal patients with hormone-receptor positive (HR+), who have not received prior therapy for early stage breast cancer. The outcomes were measured by disease-free survival (DFS) and overall survival (OS). We evaluated relative hazard ratios (HRs) for death of different therapies by combination hazard ratios for death of included trials. The SUCRA values were used to evaluate the rankings of efficacy for these monotherapies.

RESULTS

A total of fourteen studies including 19,517 patients in our research were absorbed and estimated. The superiority of efficacy for DFS were 5-year letrozole and 10-year tamoxifen (SUCRA values 0.743/0.657) in all comparisons. A more efficient SUCRA values for OS were 5-year Exemestane, 5-year letrozole and 10-year tamoxifen (0.756/0.677/0.669).

CONCLUSIONS

Clinically important differences exist between commonly prescribed different adjuvant endocrine monotherapy regimens for both efficacy and acceptability in favor of exemestane and letrozole. 10-year tamoxifen for early breast cancer patients is noninferior to 5-year anastrozle, and might be the best choice where aromatase inhibitors (AIs) are not easy to acquire.

Risk of Recurrence or Contralateral Breast Cancer More than 5 Years After Diagnosis of Hormone Receptor-Positive Early-Stage Breast Cancer

BACKGROUND

Three large studies have shown a survival benefit from 10 years of adjuvant hormone therapy (AHT). We evaluated the risk of an event 5 years after the initial breast cancer (BC) diagnosis and identified the prognostic factors to assist clinicians considering extended AHT.

PATIENTS AND METHODS

Patients newly referred to the BC Cancer Agency with stage I to III estrogen receptor-positive BC diagnosed from 1989 to 2004 who had undergone AHT were identified by the BC Cancer Agency's Breast Cancer Outcomes Unit. Cases with recurrence, death, or contralateral BC occurring within the first 5 years were excluded. The 10-year event-free survival (EFS) and 95% confidence intervals (CIs) were calculated using the Kaplan-Meier method. This provided estimates of recurrence risk after the fifth year following the diagnosis. The histopathologic and age variables were examined for prognostic value by univariate analysis.

RESULTS

Within our cohort, 6615 women were postmenopausal and 1886 were premenopausal at the BC diagnosis. The median follow-up period was 11 years. The 10-year EFS for women aged < 50 years with stage I, II, and III disease was 94.8% (95% CI, 92.8%-96.3%), 88.3% (95% CI, 86.0%-90.2%), and 80.4% (95% CI, 73.6%-85.6%), respectively. Among women aged ≥ 50 years, the corresponding EFS rates were 94.8% (95% CI, 93.8%-95.6%), 86.3% (95% CI, 85.0%-87.5%), and 73.8% (95% CI, 69.1%-77.8%). EFS varied significantly by grade. The 10-year recurrence risk was < 10% with stage I cancer (any grade) and for stage II (node-negative and node-positive), grade I cancer.

CONCLUSION

Our data have identified BCs associated with a very low recurrence risk 5 to 10 years after diagnosis, providing women with such cancers confidence about a decision to discontinue AHT after 5 years.

Extended adjuvant tamoxifen for early breast cancer: a meta-analysis

Background

Hormone receptor positive breast cancer is characterized by the potential for disease recurrence many years after initial diagnosis. Endocrine therapy has been shown to reduce the risk of such recurrence, but the optimal duration of endocrine therapy remains unclear.

Methods

We conducted a systematic review and meta-analysis to quantify the benefits and harms of extended adjuvant tamoxifen (>5 years of therapy) compared with adjuvant tamoxifen (5 years of therapy). Odds ratios (ORs) and 95% confidence intervals (CIs) were computed for disease recurrence, death and adverse events. Subgroup analyses by timing of recurrence and baseline lymph node and menopause status were carried.

Results

Five trials comprising 21,554 patients were included. Extended adjuvant tamoxifen was not associated with a significant reduction in the risk of recurrence (OR:0.89, 95% CI 0.76–1.05, p = 0.17). There was no association between extended adjuvant tamoxifen and all-cause death (OR:0.99, 95% CI 0.84–1.16, p = 0.88). There was an apparent reduction in risk of recurrence occurring after completion of extended adjuvant tamoxifen with little evidence of effect during therapy, however, this difference was not significant (p for difference 0.10). Subgroup analysis suggested that a greater effect size among lymph node positive patients compared with those who are lymph node negative (NNT: 25 vs. 49). There was no apparent difference in the effect between pre- and post-menopausal patients. Endometrial carcinoma was substantially more frequent with extended adjuvant tamoxifen (OR:2.06, 95% CI 1.65–2.58, p<0.001, number needed to harm:89).

Conclusion

In unselected patients, extended adjuvant tamoxifen is not associated with a significant reduction in recurrence, or a reduction in all-cause death. Patients with lymph node positive breast cancer may derive some benefit. Reduction in the risk of recurrence appears to occur only after completion of extended adjuvant therapy.

GPR30 as an initiator of tamoxifen resistance in hormone-dependent breast cancer

Introduction

Tamoxifen is widely used to treat hormone-dependent breast cancer, but its therapeutic benefit is limited by the development of drug resistance. Here, we investigated the role of estrogen G-protein coupled receptor 30 (GPR30) on Tamoxifen resistance in breast cancer.

Methods

Primary tumors (PTs) of breast cancer and corresponding metastases (MTs) were used to evaluate the expression of GPR30 and epidermal growth factor receptor (EGFR) immunohistochemically. Tamoxifen-resistant (TAM-R) subclones derived from parent MCF-7 cells were used to investigate the role of GPR30 in the development of tamoxifen resistance, using MTT assay, western blot, RT-PCR, immunofluorescence, ELISA and flow cytometry. TAM-R xenografts were established to assess anti-tumor effects of combination therapy with GPR30 antagonist G15 plus 4-hydroxytamoxifen (Tam), using tumor volume measurement and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL).

Results

In 53 human breast cancer specimens, GPR30 expression in MTs increased compared to matched PTs; in MTs, the expression patterns of GPR30 and EGFR were closely related. Compared to parent MCF-7 cells, TAM-R cells had greater growth responses to 17β-estradiol (E2), GPR30 agonist G1 and Tam, and significantly higher activation of Mitogen-activated protein (MAP) kinases; but this increased activity was abolished by G15 or AG1478. In TAM-R cells, GPR30 cell-surface translocation facilitated crosstalk with EGFR, and reduced cAMP generation, attenuating inhibition of EGFR signaling. Combination therapy both promoted apoptosis in TAM-R cells and decreased drug-resistant tumor progression.

Conclusions

Long-term endocrine treatment facilitates the translocation of GPR30 to cell surfaces, which interferes with the EGFR signaling pathway; GPR30 also attenuates the inhibition of MAP kinases. These factors contribute to tamoxifen resistance development in breast cancer. Combination therapy with GPR30 inhibitors and tamoxifen may provide a new therapeutic option for drug-resistant breast cancer.

Celecoxib alleviates tamoxifen-instigated angiogenic effects by ROS-dependent VEGF/VEGFR2 autocrine signaling

BACKGROUND

Tamoxifen (TAM) is widely used in the chemotherapy of breast cancer and as a preventive agent against recurrence after surgery. However, extended TAM administration for breast cancer induces increased VEGF levels in patients, promoting new blood vessel formation and thereby limiting its efficacy. Celecoxib (CXB), a selective COX-2 inhibitor, suppresses VEGF gene expression by targeting the VEGF promoter responsible for its inhibitory effect. For this study, we had selected CXB as non-steroidal anti-inflammatory drug in combination with TAM for suppressing VEGF expression and simultaneously reducing doses of both the drugs.

METHODS

The effects of CXB combined with TAM were examined in two human breast cancer cell lines in culture, MCF7 and MDA-MB-231. Assays of proliferation, apoptosis, angiogenesis, metastasis, cell cycle distribution, and receptor signaling were performed.

RESULTS

Here, we elucidated how the combination of TAM and CXB at nontoxic doses exerts anti-angiogenic effects by specifically targeting VEGF/VEGFR2 autocrine signaling through ROS generation. At the molecular level, TAM-CXB suppresses VHL-mediated HIF-1α activation, responsible for expression of COX-2, MMP-2 and VEGF. Besides low VEGF levels, TAM-CXB also suppresses VEGFR2 expression, confirmed through quantifying secreted VEGF levels, luciferase and RT-PCR studies. Interestingly, we observed that TAM-CXB was effective in blocking VEGFR2 promoter induced expression and further 2 fold decrease in VEGF levels was observed in combination than TAM alone in both cell lines. Secondly, TAM-CXB regulated VEGFR2 inhibits Src expression, responsible for tumor progression and metastasis. FACS and in vivo enzymatic studies showed significant increase in the reactive oxygen species upon TAM-CXB treatment.

CONCLUSIONS

Taken together, our experimental results indicate that this additive combination shows promising outcome in anti-metastatic and apoptotic studies. In a line, our preclinical studies evidenced that this additive combination of TAM and CXB is a potential drug candidate for treatment of breast tumors expressing high levels of VEGF and VEGFR2. This ingenious combination might be a better tailored clinical regimen than TAM alone for breast cancer treatment.

Hormonal therapy in breast cancer: a model disease for the personalization of cancer care

The treatment of breast cancer is driven by subtype classification, of which the assessment of hormone receptor status is one of the important determinants of therapy. The use of hormonal therapy to treat estrogen-receptor positive breast cancer has been studied for over a century and is one of the well-described uses of personalized medicine. In this review, we will describe the classification of hormone receptor status and the various endocrine treatment strategies. Opportunities for personalization of care are illustrated.

Adjuvant endocrine therapy for premenopausal women with breast cancer

AIMS

Endocrine therapy is a pivotal treatment for women with hormone-receptor positive breast cancer. In premenopausal women, endocrine therapy primarily consists of tamoxifen and ovarian suppressive strategies. Younger women experience improvements in the risks of relapse or death from breast cancer with the use of chemotherapy as well, with part of this benefit explained by resultant premature amenorrhea. Unfortunately despite a centuries worth of clinical trials, the most efficacious combination of hormonal therapies and chemotherapy has yet to be determined. This paper serves as a comprehensive review of the substantial data in the adjuvant treatment of premenopausal, hormone receptor-positive women with breast cancer.

METHODS AND RESULTS

PubMed and American Society of Clinical Oncology (ASCO) Proceedings searches from 1896 to present were performed. All of the trials examining the role of ovarian suppression and tamoxifen with and without chemotherapy in premenopausal women were included. The current data suggests that endocrine therapy can be an important alternative to chemotherapy in select patient populations, and improvements in outcome are also seen with the combination of hormonal and chemotherapy strategies in other populations. A majority of the trials examined did not use what is considered to be current standards of care regarding chemotherapy regimens and durations of adjuvant hormonal therapy. Many unanswered questions remain particularly regarding the combined use of ovarian suppression and tamoxifen in women who are also receiving chemotherapy.

CONCLUSION

There is a persistent need to define optimal endocrine therapy in premenopasusal women with hormone-receptor positive breast cancer. Contemporaneous trials, such as the SOFT trial will provide direction, and additional biomarker and pharmacogenomic data will further supplement individualized patient decision making.

Endocrine therapy for the treatment of postmenopausal women with breast cancer

The treatment of women with estrogen receptor-positive breast cancer has advanced significantly in the past decade. Tamoxifen was the gold standard hormonal therapy for breast cancer until the introduction of aromatase inhibitors and fulvestrant. Many of these new treatments are useful only for patients who are postmenopausal. There are data to support the use of these new agents both in the metastatic and adjuvant settings. Here, we briefly review the recent clinical trials supporting the use of these agents in both the adjuvant and metastatic settings. We will discuss possible mechanisms of resistance to endocrine agents that could be exploited therapeutically to improve the outcome for patients with hormone receptor-positive breast cancers.

Controversies of adjuvant endocrine treatment for breast cancer and recommendations of the 2007 St Gallen conference

Endocrine treatment for breast cancer was introduced more than a century ago. The discovery of hormone receptors has allowed targeting of endocrine treatment to patients whose primary tumours express these receptors. In the adjuvant setting, different approaches are used in premenopausal or postmenopausal women. In premenopausal patients, suppression of ovarian function and the use of tamoxifen are the most important therapeutic options, even though questions on timing, duration, and combination of these compounds remain unanswered. The use of aromatase inhibitors in combination with ovarian-function suppression is currently under investigation in the premenopausal setting. In postmenopausal patients, aromatase inhibitors given after 2-3 years or 5 years of tamoxifen have shown a significant benefit over tamoxifen alone. However, questions on this treatment also remain unanswered. For example, whether all patients should receive an aromatase inhibitor or whether some subgroups of patients might be optimally treated by tamoxifen alone is yet to be established. In this paper we review the published work on adjuvant endocrine treatment in breast cancer and provide recommendations from the 2007 St Gallen International Conference on Primary Therapy of Early Breast Cancer.

Patient centered experiences in breast cancer: predicting long-term adherence to tamoxifen use

BACKGROUND

Among breast cancer patients, tamoxifen use is associated with reduced risk of disease relapse and death, but it is often difficult for women to sustain therapy during the 5 years required to obtain maximum benefit.

OBJECTIVES

We sought to examine the influence of patient-centered care activities on ongoing tamoxifen use 4 years after initiation, we examined key components of patient-centered care and rates of ongoing tamoxifen.

METHODS

Using a prospective cohort study that included observational data from the National Initiative for Cancer Care Quality (NICCQ), we studied 881 patients with stage I-III breast cancer who were registered with an initial diagnosis in 1998 by an American College of Surgeons-approved hospital cancer registry in 1 of 5 metropolitan areas, who initiated tamoxifen treatment. A patient survey and medical record abstraction were used as measurements.

RESULTS

Among women who initiated tamoxifen, 79% were still taking it 4 years later. Other than older age and the severity of side effects, other demographic, clinical and cancer characteristics, and treatments did not predict ongoing tamoxifen use. In contrast, after adjusting for these factors, the proportion of patients with ongoing tamoxifen use was lower for patients reporting less support than needed (82% vs. 69%, P = 0.0051), less than wanted role in decision-making (80% vs. 70%, P = 0.0486), decision-making about tamoxifen without doctor input (79% vs. 64%, P = 0.0182), and for patients who weren't told about side effects in advance (82% vs. 72%, P = 0.0016).

CONCLUSIONS

Although age and the severity of side-effects remain important, patient-centered care was a primary mediator of patient adherence to ongoing cancer treatment with tamoxifen.

Breast Cancer Adjuvant Endocrine Therapy

Adjuvant endocrine therapy with the selective estrogen receptor modulator, tamoxifen, has significantly improved mortality from early-stage breast cancer for both pre- and postmenopausal women with hormone receptor-positive breast cancer. Recent large clinical trials have demonstrated a clear and consistent benefit for the incorporation of aromatase inhibitor (AI) therapy within adjuvant endocrine regimens for postmenopausal women. The AIs, which are associated with myalgias, arthralgias, and a reduction in bone mineral density, are generally well tolerated and have lower risks of endometrial carcinoma and thromboembolic events than tamoxifen. Data are awaited from ongoing trials to better define the optimal sequencing strategy, duration, and AI agent. Attempts to further optimize adjuvant endocrine therapy by identifying predictive biomarkers of response, as well as by developing strategies to overcome endocrine resistance are underway. In premenopausal women AI monotherapy is currently contraindicated and tamoxifen remains the standard of care. The role of ovarian function suppression in addition to tamoxifen or combined with AI therapy is being explored. The hope is that continued advances in endocrine therapy will translate into improved survival among both pre- and postmenopausal women with receptor-positive breast cancer.

Use of adjuvant systemic therapy for early breast cancer among women 65 years of age and older

BACKGROUND

The National Institutes of Health (NIH) consensus statement recommends adjuvant therapy for early breast cancer irrespective of age. However, the actual use of such therapy is not well documented among women over 65 years of age.

METHODS

We studied the frequency of use of adjuvant therapy and report the receipt of this therapy among 200 women aged > or = 65 years diagnosed with early breast cancer who were identified from the New Jersey State Cancer Registry.

RESULTS

In this population, 28% of patients received chemotherapy alone or in combination with hormonal therapy, whereas 42% received hormonal therapy alone. Less than half of the women with estrogen receptor-negative tumors received chemotherapy alone or in combination with hormonal treatment. Adjuvant therapy was not prescribed in 30% of patients.

CONCLUSIONS

Despite NIH recommendations, the frequency of use of adjuvant therapy in New Jersey is low among women over 65 years of age, regardless of their receptor status.

Postoperative adjuvant chemotherapy followed by adjuvant tamoxifen versus nil for patients with operable breast cancer: a randomised phase III trial of the European Organisation for Research and Treatment of Cancer Breast Group

BACKGROUND

The contribution of adjuvant tamoxifen in breast cancer patients after receiving adjuvant chemotherapy is not fully established. We investigated the impact of tamoxifen, given sequentially after completion of adjuvant chemotherapy in patients with operable breast cancer.

PATIENTS AND METHODS

Between March 1991 and June 1999, 1863 women with stages I-IIIA operable breast cancer who had undergone surgery and completed six cycles of adjuvant combination chemotherapy with either CMF, CAF, CEF, FAC or FEC were randomised to receive either tamoxifen 20 mg daily for 3 years or no further treatment. Irrespective of menstrual status and hormone receptor content of the primary tumour, patients were stratified by institute, chemotherapy scheme and age (above 50 years or younger). The main end-point was to detect a 5% increase in the 5 year survival (from 80% to 85%) in favour of antioestrogen therapy. Secondary end-points were relapse free survival (RFS), local control, incidence of second primary breast cancer and correlation of results with hormone receptor content.

RESULTS

After exclusion of all patients from three sites because of inadequate documentation, a total of 1724 patients (93%) were analysed (Tam 861 and Control 863). At a median follow-up of 6.5 years, 5-year RFS on tamoxifen was 73% versus 67% in controls (p=0.035). No difference was seen in overall survival. The benefit of tamoxifen therapy was mainly seen in the subgroup of patients with histologically documented positive axillary nodes (5-year RFS on tamoxifen 71% versus 64% in the control group, p=0.044) and in patients with tumours expressing the ER and PR positive phenotype (5-year RFS on tamoxifen 77% versus 70% in the control group, p=0.014).

CONCLUSIONS

Tamoxifen administered for 3 years after completion of adjuvant chemotherapy in this otherwise unselected group of patients for endocrine sensitivity had a limited impact on relapse and had no detectable effect on overall survival. The beneficial effect of tamoxifen is mainly confined to the subgroup of patients with node-positive disease and to patients with tumours expressing the ER and PR positive phenotype.

Twelve-year mortality results of a randomized trial of 2 versus 5 years of adjuvant tamoxifen for postmenopausal early-stage breast carcinoma patients (SITAM 01)

BACKGROUND

This study evaluated the impact on overall survival (OS) of 2 versus 5 years adjuvant tamoxifen in early breast carcinoma patients after 12 years of follow-up.

METHODS

Women with breast carcinoma T1-3, N0-3, M0, aged 50-70 years, were eligible for this multicenter randomized Phase III trial. Patients event-free after 2 years of tamoxifen therapy (TAM) were randomly assigned to stop or continue TAM (20 mg/day) for an additional 3 years. The primary endpoint was disease-free survival. Secondary endpoints included OS and toxicity.

RESULTS

From 1989 through 1996, 1901 patients were randomly assigned either to stop treatment (n = 958) or to continue TAM (n = 943). Overall, 98% of patients alive at the previous report (n = 1611) had updated information about OS, of whom 549 had died. The median duration of postrandomization follow-up was 115 months (interquartile range, 86-137). No statistically significant differences between the two arms were detected in the whole population (hazard ratio [HR], 1.02; 95% confidence interval [CI], 0.86-1.22) and in estrogen receptor (ER)-positive patients (HR, 0.90; 95% CI, 0.72-1.13). In the latter group, survival curves started to diverge after 90 months, showing a trend in favor of the 5-year arm. In younger (age < or =55 yrs) ER-positive patients longer TAM was associated with a 44% decrease in the risk of death (HR, 0.56; 95% CI, 0.31-1.00), while no clear benefit was documented in women older than 55 years of age (HR, 0.98; 95% CI, 0.77-1.25).

CONCLUSIONS

The benefits of longer TAM on OS start to emerge only after 9 years from diagnosis and seem to be more relevant in younger ER-positive women.

Results of two randomized trials evaluating adjuvant anthracycline-based chemotherapy in 1146 patients with early breast cancer

Two randomized trials evaluated the effect of 6 courses of anthracycline-based chemotherapy in early breast cancer. A total of 1146 patients were included: 311 high-risk node-negative premenopausal patients and 835 high-risk node-negative or node-positive postmenopausal patients. Patients were randomized after surgery to receive either no chemotherapy (control group) or 6 courses of anthracycline-based chemotherapy (CT group). Postmenopausal patients received adjuvant tamoxifen for at least two years. Radiotherapy was delivered after completion of chemotherapy in the CT group. The 10-year disease-free survival (DFS) rates were 60% in the control group and 65% in the CT group (log-rank test, p = 0.01). The 10-year distant metastasis rates were 28% and 23% (p = 0.02), and the 10-year local recurrence rates were 12% and 10%, respectively (p = 0.24). Chemotherapy was significantly less effective in post-menopausal patients with estrogen receptor-positive tumors. Adjuvant anthracycline-based chemotherapy yielded a significant benefit for DFS by lowering the risk of distant metastases. After up to 10 years of follow-up, deferring radiotherapy after chemotherapy did not compromise local control.

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.

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.

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.

Randomized trial of 2 versus 5 years of adjuvant tamoxifen for women aged 50 years or older with early breast cancer: Italian Interdisciplinary Group Cancer Evaluation Study of Adjuvant Treatment in Breast Cancer 01

PURPOSE

To compare 2 with 5 years of adjuvant tamoxifen therapy in the treatment of early breast cancer.

PATIENTS AND METHODS

Women with breast carcinoma T1-3, N0-3, M0, who were between 50 and 70 years of age, were eligible irrespective of menopausal status, tumor grade, or estrogen receptor (ER) status. Patients who were event-free after 2 years of tamoxifen therapy were randomly assigned to stop or continue tamoxifen therapy for an additional 3 years. The primary end point was length of disease-free survival (DFS). Secondary end points included overall survival (OS) and toxicity.

RESULTS

From 1989 through 1996, 1,901 patients were randomly assigned either to stop treatment (n = 958) or to receive tamoxifen for 3 additional years (n = 943). The median duration of postrandomization follow-up was 52 months. We found no statistically significant differences between the 5-year arm and the 2-year arm in terms of DFS (hazard ratio [HR], 0.91; 95% confidence interval [CI], 0.76 to 1.08) and OS (HR, 1.16; 95% CI, 0.92 to 1.46). In ER-positive patients, a statistically significant prolongation of DFS related to longer treatment duration was observed (HR, 0.74; 95% CI, 0.59 to 0.93), whereas no difference in OS could be detected (HR, 0.98; 95% CI, 0.72 to 1.32). No differences in terms of endometrial cancers, cardiac or cerebrovascular events, or fractures were detected, whereas a doubling in the risk of thromboembolic events was found in the 5-year arm.

CONCLUSION

Our results confirm previous research that shows that 5 years of tamoxifen decreases recurrence compared to 2 years in patients with ER-positive tumors.

Patterns of failure in a randomized trial of adjuvant chemotherapy in postmenopausal patients with early breast cancer treated with tamoxifen

BACKGROUND

We studied the effect of adjuvant anthracycline-based chemotherapy in postmenopausal patients with resected early breast cancer treated with adjuvant tamoxifen.

PATIENTS AND METHODS

The trial included 835 patients with either axillary lymph node involvement, or tumors with histological grade II or III. They were randomized after local surgery to receive either tamoxifen (TAM group) or tamoxifen plus chemotherapy (TAM-CT group) consisting of six courses of 5-fluorouracil, doxorubicin and cyclophosphamide (FAC), or 5-fluorouracil, epidoxorubicin and cyclophosphamide (FEC). Radiotherapy was given after completion of adjuvant chemotherapy in the TAM-CT group and after surgery in the TAM group.

RESULTS

The 5-year disease-free survival (DFS) rates were 73% in the TAM group and 79% in the TAM-CT group (log-rank test, P = 0.06). The 5-year overall survival rates were 82% and 87%, respectively (P = 0.06). The 5-year distant metastasis rates were 22% and 16% (P = 0.02), and the 5-year local recurrence rates were 6% and 4%, respectively (P = 0.23). There were no significant differences for contralateral breast cancer or other new primary malignancies. Chemotherapy tended to be more effective for patients who had tumors without estrogen receptors (trend test, P = 0.05).

CONCLUSIONS

Anthracycline-based chemotherapy administered to postmenopausal patients receiving adjuvant tamoxifen gave a borderline significant benefit on overall and DFS, mainly by a reduction in distant metastases. Delaying radiotherapy after six courses of chemotherapy did not affect local control after up to 10 years of follow-up.

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.

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.