Cost effectiveness of extended adjuvant letrozole in postmenopausal women after adjuvant tamoxifen therapy: the UK perspective

The Effect of the Drug Life Cycle Price on Cost-Effectiveness: Case Studies Using Real-World Pricing Data

OBJECTIVES

Cost-effectiveness analyses (CEAs) generally assume constant drug prices throughout the model time horizon, yet it is known that prices are not constant, often with price decreases near loss of exclusivity (LOE). This study explores the impact of using dynamic drug-specific prices on the incremental cost-effectiveness ratio (ICER) using selected reproduced case studies.

METHODS

Case studies were selected following explicit criteria to reflect a variety of drug characteristics. For each drug, a published CEA model was identified, replicated, and modified with dynamic real-world pricing data, to compare ICERs based on constant drug prices with estimates obtained when including drug life cycle pricing. The impact of dynamic real-world pricing-inclusive LOE-was analyzed using a single patient cohort and multiple cohorts over time.

RESULTS

Fluvastatin, alendronic acid + colecalciferol combination therapy, letrozole and clopidogrel were selected as case studies. Inclusion of real-world pricing data compared with applying constant prices reduced the ICER in a single-cohort setting up to 43%. In the multicohort analyses, further reductions of the ICERs were observed of up to 113%. The ICERs were sensitive to the period of drug usage relative to the models' time horizons, the relative proportions of drug costs in the overall treatment costs, and timing of LOE compared with the cost year of the original analysis.

CONCLUSIONS

Assuming dynamic drug prices may lead to more representative ICER estimates. Future CEAs for drugs could account for predicted and disaggregated life cycle price developments based on retrospective data.

A Critique and Impact Analysis of Decision Modeling Assumptions

Background . Numerous guidelines have been published defining good practice for the conduct of economic evaluations in general and model-based evaluations in particular. The extent to which guidelines are accepted is unknown, and the impact of deviations from good practice is not generally recorded. The authors identified 4 specific issues in applied studies that may affect the accuracy and comparability of different evaluations. Methods . A descriptive analysis of 4 modeling issues (inclusion of incident cases over a model time horizon, appropriate time horizon, parsimonious model structure, and the handling of age-specific subgroups) is presented. A case study model is analyzed to illustrate the quantitative impact of 3 of the issues. Results . In the case study model, alternative specifications of the modeling framework are shown to alter the estimated cost-effectiveness by large percentages. The combined effect of including incident cases and reduced follow-up yielded the highest divergence from the reference case results, by between 20% and 40%, depending on the age group. Reference case results of an age-weighted population were almost 14% different from the middle single age cohort. Discussion . The identified issues are all generalizable to a wide range of treatment areas and are, or should be, addressed by evaluative guidelines. The authors call for the continued development, dissemination, and application of guidelines for the conduct of economic evaluation in general and model-based economic evaluations in particular.

Cost-utility analyses of drug therapies in breast cancer: a systematic review

The economic evaluation (EE) of health care products has become a necessity. Their quality must be high in order to trust the results and make informed decisions. While cost-utility analyses (CUAs) should be preferred to cost-effectiveness analyses in the oncology area, the quality of breast cancer (BC)-related CUA has been given little attention so far. Thus, firstly, a systematic review of published CUA related to drug therapies for BC, gene expression profiling, and HER2 status testing was performed. Secondly, the quality of selected CUA was assessed and the factors associated with a high-quality CUA identified. The systematic literature search was conducted in PubMed, MEDLINE/EMBASE, and Cochrane to identify published CUA between 2000 and 2014. After screening and data extraction, the quality of each selected CUA was assessed by two independent reviewers, using the checklist proposed by Drummond et al. The analysis of factors associated with a high-quality CUA (defined as a Drummond score ≥7) was performed using a two-step approach. Our systematic review was based on 140 CUAs and showed a wide variety of methodological approaches, including differences in the perspective adopted, the time horizon, measurement of cost and effectiveness, and more specially health-state utility values (HSUVs). The median Drummond score was 7 [range 3-10]. Only one in two of the CUA (n = 74) had a Drummond score ≥7, synonymous of "high quality." The statistically significant predictors of a high-quality CUA were article with "gene expression profiling" topic (p = 0.001), consulting or pharmaceutical company as main location of first author (p = 0.004), and articles with both incremental cost-utility ratio and incremental cost-effectiveness ratio as outcomes of EE (p = 0.02). Our systematic review identified only 140 CUAs published over the past 15 years with one in two of high quality. It showed a wide variety of methodological approaches, especially focused on HSUVs. A critical appraisal of utility values is necessary to better understand one of the main difficulties encountered by authors and propose areas for improvement to increase the quality of CUA. Since the last 5 years, there is a tendency toward an improvement in the quality of these studies, probably coupled with economic context, a better and widely spreading of recommendations and thus appropriation by medical practitioners. That being said, there is an urgent need for mandatory use of European and international recommendations to ensure quality of such approaches and to allow easy comparison.

Comparison of breast cancer recurrence and outcome patterns between patients treated from 1986 to 1992 and from 2004 to 2008

PURPOSE

To determine whether the patterns of relapse according to estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) status changed in the contemporary era.

PATIENTS AND METHODS

Female patients referred to the British Columbia Cancer Agency with biopsy-proven stage I to III breast cancer (BC), diagnosed between 1986 and 1992 (cohort 1 [C1]) and between mid-2004 and 2008 (cohort 2 [C2]), and with known ER and HER2 status were eligible. Data were prospectively collected. C2 patients were matched to C1 patients for stage, grade, and ER and HER2 status. The primary end point was hazard rate of relapse (HRR) for BC by study cohort according to biomarker status. Secondary outcomes included HRR according to stage, grade, and age and hazard rate of death (HRD).

RESULTS

After matching, 7,178 patients were included (3,589 patients in each cohort). BC subtype distribution was as following ER positive/HER2 negative, 70.8%; ER positive/HER2 positive, 6.9%; ER negative/HER2 positive, 6.6%; and ER negative/HER2 negative, 15.8%. For the overall population, the HRR approximately halved in all yearly intervals to year 9 in C2 compared with C1. Differences in HRR between cohorts were greater in the initial five intervals for HER2-positive and ER-negative/HER2-negative BC. The HRR decreased in C2 compared with C1 for all disease stages and grades. The HRD in C2 also decreased compared with C1, although to a lesser extent.

CONCLUSION

Although the pattern of relapse remains similar, there has been a significant improvement in BC relapse-free survival. Outcomes have improved for all BC subtypes, especially HER2-positive and ER-negative/HER2-negative BC, with the early spike in disease recurrence markedly decreased. These contemporary hazard rates are important for treatment decisions, patient discussions, and planning clinical trials of early BC.

Extended adjuvant therapy with letrozole: reducing the risk of recurrence

Patients with all stages of primary breast cancer are at continuing risk of relapse following 5 years of adjuvant tamoxifen therapy, even in the absence of lymph node involvement. Tamoxifen has been the standard therapy for reducing risk of recurrence, although more than 50% of relapses and deaths occur after completion of tamoxifen. Tamoxifen use is associated with an increased risk of serious side effects, and extended use beyond 5 years may have a negative impact on disease-free survival. Extended adjuvant letrozole therapy confers a significant benefit in relapse-free survival. The approval of letrozole for this indication in the USA and in many European countries introduces a new, safe and effective treatment for disease-free patients seeking to reduce their long-term risk of recurrence.

Extended adjuvant endocrine therapy in hormone dependent breast cancer: the paradigm of the NCIC-CTG MA.17/BIG 1-97 trial

Early hormone-receptor-positive breast cancer is a chronic relapsing disease that can remain clinically silent for many years. The NCIC-CTG MA.17/BIG 1-97 trial randomized disease-free early breast cancer patients who had received five years of adjuvant tamoxifen to either letrozole or placebo and was the first to demonstrate a benefit with extended endocrine therapy. MA.17/BIG 1-97 was stopped at the first interim analysis because disease free survival was strongly prolonged in the letrozole arm. Subsequent subset analyses and longer follow up have shown that this therapy improved survival across all groups, particularly among women with node-positive disease and those that were pre-menopausal at time of study enrolment. The MA.17/BIG 1-97 study should be considered a paradigm for extended adjuvant endocrine therapy in hormone-receptor-positive early breast cancer.

Cost-effectiveness of letrozole, anastrozole and exemestane for early adjuvant breast cancer

Clinical trials have shown aromatase inhibitors to be a more effective hormonal therapy for preventing recurrence in postmenopausal women with hormone receptor-positive early breast cancer. However, the aromatase inhibitors have an alternative adverse event profile and are more expensive than tamoxifen. This review identifies 15 separate cost-effectiveness analyses that have assessed the incremental cost per quality-adjusted life year gained of one or more aromatase inhibitor treatment strategies compared with tamoxifen. We found many similarities between the studies and the overriding conclusion was that the aromatase inhibitor strategies are cost effective relative to 5-year tamoxifen treatment. This conclusion is shared by the National Institute for Clinical Excellence in the UK. Comparisons between the aromatase inhibitors are hampered as none of the clinical trials included a direct comparison, although an ongoing trial is addressing this issue.

Reviewing the cost-effectiveness of endocrine early breast cancer therapies: influence of differences in modeling methods on outcomes

OBJECTIVES

The purpose of this systematic review is primarily to identify published cost-effectiveness analyses and cost-utility analyses of endocrine therapies for the treatment of early breast cancer. A secondary objective is to identify whether differences in seven modeling characteristics are related to differences in outcome of these cost-effectiveness and cost-utility analyses.

METHODS

A systematic literature review was conducted to identify peer-reviewed full economic evaluations of endocrine treatments of early breast cancer published in the English language between 2000 and December 2010. Information from these publications was abstracted regarding outcome, quality, and modeling methods.

RESULTS

We identified 20 economic evaluations comprising 5 different endocrine therapeutic strategies, which are all assessed more then once. The incremental cost-effectiveness ratios (ICERs) of the reported outcomes varied widely for identical therapies. For anastrazole compared to tamoxifen, incremental life-years gained even ranged from 0.16 to 0.550 with an ICER ranging from €3,958 to €75,331. Incremental quality-adjusted life-years (QALYs) gained ranged from 0.092 to 0.378 with a cost per QALY gained varying from €3,696 to €120,265. These large differences in outcome were related to different modeling methods, with differences in time horizon and use of a carryover effect as most prominent causes.

CONCLUSION

Despite similar comparators and logical differences due to transferability issues, the outcomes of the included studies varied widely. To increase comparability and transparency of pharmacoeconomic evaluations, standardization of modeling methods for different therapeutic groups/diseases and the availability of a detailed and complete description of the model used in the evaluation is advocated. Recommendations for standardization in modeling treatment strategies in early breast cancer are presented.

Aromatase inhibitors versus tamoxifen as adjuvant hormonal therapy for oestrogen sensitive early breast cancer in post-menopausal women: meta-analyses of monotherapy, sequenced therapy and extended therapy

Adjuvant tamoxifen reduces relapses and prolongs survival in patients with oestrogen sensitive breast cancer. Development of resistance is however common. Tamoxifen can be given for a maximum of five years; although the risk of recurrences remains high after this period. This review examines nine randomised controlled trials including 28,632 women, which studied aromatase inhibitors (AIs) as an alternative to tamoxifen in three treatment settings: monotherapy (instead of tamoxifen), sequenced therapy (tamoxifen is switched to an AI) and extended therapy (following adjuvant tamoxifen). Disease free survival was significantly improved for monotherapy (HR 0.89, [95% CI 0.83-0.96] p = 0.002) and sequenced therapy (HR 0.72, [0.63-0.83] p < 0.00001). There was no difference in overall survival for monotherapy (HR 0.94, [0.82-1.08] p = 0.39) or extended therapy (HR 0.86 [0.79-1.16] p = 0.67). Importantly, overall survival was prolonged for patients who switched from tamoxifen to AI therapy (HR 0.78 95%CI 0.68-0.91, p = 0.001).

Letrozole: a review of its use in the treatment of postmenopausal women with hormone-responsive early breast cancer

Letrozole (Femara) is a third-generation, nonsteroidal aromatase inhibitor. Adjuvant therapy with letrozole is more effective than tamoxifen in postmenopausal women with hormone-responsive early breast cancer, and extended adjuvant therapy with letrozole after the completion of adjuvant tamoxifen therapy is more effective than placebo in this patient population; letrozole is generally well tolerated. Ongoing trials will help answer outstanding questions regarding the optimal duration of letrozole therapy in early breast cancer and its efficacy compared with other third-generation aromatase inhibitors such as anastrozole. In the meantime, letrozole should be considered a valuable option in the treatment of postmenopausal women with hormone-responsive early breast cancer, both as adjuvant and extended adjuvant therapy.

Trastuzumab for the treatment of primary HER2-positive breast cancer in HER2-positive women: a single technology appraisal

This paper presents a summary of the evidence review group (ERG) report into the the clinical and cost-effectiveness of trastuzumab for the treatment of primary breast cancer in human epidermal growth factor 2 (HER2)-positive women based upon a review of the manufacturer’s submission to the National Institute for Health and Clinical Excellence (NICE) as part of the single technology appraisal (STA) process. The manufacturer’s scope restricts the intervention to intravenous trastuzumab given for 1 year after surgery and after the completion of standard adjuvant chemotherapy, and the comparator to standard therapy without trastuzumab. The clinical rationale for the duration of treatment in the scope is open to question and leads to the exclsuion of one potentially relevant trial. The submitted evidence reports that the 3-weekly regimen of trastuzumab produced a relative reduction in all-cause mortality of 24–33%. Meta-analysis of all available studies based on 12 months of trastuzumab showed that there was a statistically significant 30% relative improvement in overall survival using the 3-weekly regimen. A study looking at weekly cycles of trastuzumab, excluded in the manufacturer’s submission, produced a relative reduction in all-cause mortality of 59%, which was not statistically significant. All included studies showed a statistically significant difference in the risk of recurrence or death from any cause (disease-free survival), favouring trastuzumab. There was a statistically significant increase in the relative risk of a serious adverse event in women treated with 3-weekly cycles of trastuzumab, with no excess toxicity in the study evaluating weekly cycles. Estimates of cost-effectiveness provided by the manufacturer were based on data from the HERA trial using the 3-weekly regimen of trastuzumab. The economic model was a state-transition model that compared the lifetime impact of adding 1 year of trastuzumab therapy to standard care with standard care alone. The initial cost-effectiveness estimate was £5687 per additional quality-adjusted life-year (QALY) gained, rising to a maximum of £8689 upon one-way sensitivity analysis. The base-case estimate of cost-effectiveness was subsequently revised by the manufacturer, resulting in an estimated incremental cost per additional QALY gained of £2387. A number of assumptions behind the manufacturer’s model may be optimistic and could mean that the incremental costs per QALY gained were underestimated. Additional analysis carried out by the evidence review group concluded that the incremental cost-effectiveness ratio (ICER) is expected to be around £20,000 to £30,000. The addition of potential long-term cardiac events could push the ICER above £30,000, although there is no long-term evidence to date surrounding this issue. In addition, the small study excluded from the manufacturer’s submission raises the possibility of an equally effective but shorter regimen, incurring lower cost and toxicity and with greater patient convenience. The guidance issued by NICE in June 2006 as a result of the STA states that trastuzumab, given at 3-week intervals for 1 year or until disease recurrence, is recommended as a treatment option for women with early-stage HER2-positive breast cancer following surgery, chemotherapy and radiotherapy.

Overcoming recurrence risk: extended adjuvant endocrine therapy

Recurrence risk after initial treatment of breast cancer is a major concern for patients. Although tamoxifen therapy has been shown to be effective in preventing recurrences and cancer-related deaths, recurrences continue to be an issue for patients after the 5-year therapy period. Until recently, there were no therapeutic options available for risk reduction in the period after the first 5 years of tamoxifen (the extended adjuvant setting). The introduction of the aromatase inhibitors (AIs), which have a different mechanism of action than tamoxifen, has provided an option for postmenopausal women seeking to extend their adjuvant hormonal treatment. The Canadian-led MA.17 trial specifically addressed this issue, and the results showed a clear, significant benefit of letrozole, improving disease-free survival over placebo among postmenopausal women who already had 5 years of adjuvant tamoxifen treatment. Because of the favorable results observed in the first interim analysis, the trial was unblinded, the patients treated with placebo were offered letrozole, and subsequently, letrozole became approved for the extended adjuvant indication. Recent analyses from MA.17 and other trials, such as the Austrian Breast and Colorectal Cancer Study Group 6a and National Surgical Adjuvant Breast and Bowel Project B-33, confirm the beneficial effect of extending adjuvant hormonal therapy with an AI and identify a large group of patients who could benefit from this therapeutic option. Recent post-unblinding analyses from the MA.17 trial have also shown that there is a benefit for patients to initiate late extended adjuvant letrozole therapy, even after a prolonged period off tamoxifen.

Cost-effectiveness analysis of adjuvant therapy for operable breast cancer from a Chinese perspective: doxorubicin plus cyclophosphamide versus docetaxel plus cyclophosphamide

An oncology trial compared four cycles of doxorubicin/cyclophosphamide (AC) with four cycles of docetaxel/cyclophosphamide (TC) in operable breast cancer patients (71% were diagnosed with hormone receptor positive and 48% with node-negative breast cancer). The objective of this study was to estimate the lifetime cost effectiveness of AC versus TC, from a Chinese healthcare provider perspective, based on a clinical trial. A lifetime cost-effectiveness analysis was performed using a Markov model. Events rates and utilities in the Markov model were derived from published papers. Data on cost of breast cancer care were obtained from the Second Xiangya Hospital of Central South University, Changsha, PR China. One-way sensitivity analysis and probabilistic sensitivity analysis were undertaken. Cost estimates were valued in Chinese yuan (Y), year 2008 values. All costs and outcomes were discounted at 3% per annum. Patients receiving TC gained 14.45 QALYs, 0.41 QALYs more than patients receiving AC. The lifetime costs of patients receiving TC were Y93 511, Y10 116 more than that of AC patients. The incremental cost-effectiveness ratios were Y26 742 per life-year gained ( pound 2719.8 per year) and Y24 305 per QALY gained ( pound2471.9 per QALY). The most sensitive parameter in the model was the cost of primary cancer treatments in the TC arm. At a threshold willingness to pay of Y86 514 per QALY, the probability of TC being cost effective was 90%. Our model suggests that TC may be considered cost effective from a Chinese healthcare provider perspective, according to the threshold defined by the WHO.

Never too late: reducing late breast cancer relapse risk

BACKGROUND

Breast cancer is the most common cancer diagnosed in Europe, with an estimated 429,900 new cases diagnosed in 2006. For over 20 years, tamoxifen was the standard adjuvant (postoperative) endocrine treatment for hormone receptor-positive (i.e., endocrine-responsive) early breast cancer. Yet, even after the first 5 years, patients with hormone receptor-positive tumours are at risk of relapse. Particularly in endocrine-responsive disease, most instances of relapse and breast cancer mortality occur after the first 5 years.

SCOPE

Extended adjuvant aromatase inhibitor therapy (EAT) now offers postmenopausal women the opportunity to further protect themselves against late relapse.

METHODS

This review summarises the clinical evidence and gives practical recommendations for discussing EAT with patients. Relevant information on patients receiving extended or late extended adjuvant endocrine therapy was obtained from databases and congress websites. The most substantial evidence for EAT is provided by the MA.17 trial using letrozole, with similar results obtained from smaller studies using anastrozole or exemestane.

FINDINGS

Extended adjuvant letrozole reduced the risk of recurrence by 42% and the risk of distant metastases by 40%, it was well tolerated compared to placebo; among lymph node-positive patients, overall survival was significantly improved. Ideally, EAT should be started within 3 months of finishing tamoxifen therapy, and evidence supports its use for at least 4 years, showing increasing benefit with longer treatment duration. It is also effective, even after a longer time period, following completion of tamoxifen therapy. When deciding whether or not to use EAT after tamoxifen, clinicians and patients should consider the residual risk of relapse, comorbidities and individual preferences.

Efficacy and safety of aromatase inhibitors in early breast cancer

BACKGROUND

Third-generation aromatase inhibitors (AIs) are surfacing as the standard adjuvant treatment for postmenopausal women with hormone receptor positive breast cancer over tamoxifen but their long-term effects are still under investigation.

OBJECTIVE

In the light of current information, what factors should health practitioners take into consideration when prescribing AIs to patients?

METHODS

Results of several randomized controlled adjuvant clinical trials were reviewed to assess the efficacy of treatment and their subprotocols focusing on quality of life and skeletal health to highlight the safety concerns.

CONCLUSION

To prevent early recurrences, AIs should be considered as the upfront hormonal treatment of choice. They are also recommended for use as a switching strategy after 2-3 years of tamoxifen and as extended adjuvant treatment after 5 years of tamoxifen. The adverse events experienced are manageable and overall quality of life is not compromised; however, bone density must be monitored for patients at risk and appropriate bone-protection supplements need to be taken.

Methodological issues in evaluating cost effectiveness of adjuvant aromatase inhibitors in early breast cancer: a need for improved modelling to aid decision making

The optimal adjuvant hormonal strategy in post-menopausal women with early breast cancer is a subject of ongoing debate. Aromatase inhibitors (AIs) have been successfully evaluated in clinical trials that have compared them with a standard treatment of 5 years of tamoxifen. However, several options are available in terms of treatment schedule and selected drug. Systematic reviews of clinical trials and health economic evaluations attempt to contribute to the debate. The objective of this paper is to provide a critical review of existing health economic evaluations with a focus on those parameters and assumptions with the largest impact on final outcomes.A wide range of different inputs and assumptions exist, which make a comparison of results difficult, if not impossible. In particular, the modelling of recurrence rates over longer time horizons than those observed in clinical trials, a cornerstone of health economic modelling, is subject to quite different approaches. The practice of indirect comparison of different AIs without sufficiently acknowledging population differences is also bothersome. A list of key features (related to time horizon, clinical data input, patient subtypes, budget impact and model calibration) that an ideal model should have in order to better assist decision makers in this field is proposed.

Beyond tamoxifen: extended and late extended endocrine therapy in postmenopausal early breast cancer

Breast cancer is a leading cause of cancer death among women worldwide. The majority of cases are oestrogen receptor- or progesterone receptor-positive and, therefore, potentially sensitive to endocrine therapy. A significant risk of recurrence and death persists following initial diagnosis, with over one half of all recurrences and two thirds of breast cancer-related deaths reported to occur following completion of standard adjuvant tamoxifen therapy. There is a need for effective protection against recurrence beyond the initial 5 years of adjuvant treatment for women with hormone-responsive cancer. Extended adjuvant endocrine therapy with letrozole following completion of adjuvant tamoxifen treatment is well tolerated and reduces recurrence risk by 42% and the risk of developing distant metastases by 40% when compared with placebo. Extended adjuvant letrozole therapy confers protection against late relapses and should be considered for women completing adjuvant tamoxifen therapy. The MA.17 trial was unblinded early because of a statistically significant benefit in disease-free survival with letrozole, and patients receiving placebo were allowed to receive letrozole. MA.17 post-unblinding results show that women originally randomised to placebo who then chose to receive letrozole at the time of trial unblinding experienced a significant improvement in all outcomes (disease-free survival and distant disease-free survival), including a significant survival advantage when compared with women in the placebo arm who chose to continue with no further treatment. Physicians should consider late extended adjuvant therapy for women who have been off tamoxifen for some time, as it may offer benefit in outcomes, and this option should be discussed.

Prescribing extended adjuvant letrozole

The efficacy of 5 years of adjuvant tamoxifen in preventing disease recurrence in patients with breast cancer has been well established. Once patients have completed tamoxifen therapy, however, recurrence risk remains but treatment options are limited. Aromatase inhibitors such as letrozole are emerging as potential alternatives to tamoxifen therapy and as an option after tamoxifen. The pioneering MA-17 trial was designed to evaluate the efficacy and safety of letrozole in the extended adjuvant setting in postmenopausal women who remained disease-free after about 5 years of tamoxifen. The trial was unblinded at first interim analysis after letrozole proved more effective than placebo in improving disease-free survival. As such, the optimal duration of extended adjuvant letrozole was left in question. However, recent results from cohort analysis in MA-17 have shown an ongoing and increasing benefit of letrozole for up to 4 years after tamoxifen, suggesting that longer periods of extended adjuvant letrozole are safe and clinically beneficial.

Cost-effectiveness of letrozole versus tamoxifen as initial adjuvant therapy in hormone receptor-positive postmenopausal women with early-stage breast cancer

BACKGROUND

In Breast International Group (BIG) 1-98, a randomized, double-blind trial comparing 5 years of initial adjuvant therapy with letrozole versus tamoxifen in postmenopausal women with hormone receptor-positive early breast cancer, letrozole significantly improved disease-free survival by 19% and reduced risk of breast cancer recurrence by 28% and distant recurrence by 27%.

PATIENTS AND METHODS

A Markov model was used to estimate the incremental cost per quality-adjusted life year (QALY) gained with 5 years of initial adjuvant therapy with letrozole versus tamoxifen from a US health care system perspective. Probabilities and costs of breast cancer recurrence and treatment-related adverse events and health-state utilities were based on published results of BIG 1-98 and other published studies. Costs and QALYs were estimated over the lifetime of a cohort of postmenopausal women with hormone receptor-positive early breast cancer, aged 60 years at initiation of therapy. In our base case, we assumed that benefits of letrozole on risk of breast cancer recurrence are maintained for 5 years after therapy discontinuation ("carry-over effect") and examined the effects of this assumption on results in sensitivity analyses.

RESULTS

Under base-case assumptions, letrozole yields an additional 0.409 QALYs versus tamoxifen at an additional cost of $9705, yielding a cost per QALY gained for letrozole versus tamoxifen of $23,743 (95% confidence interval, $14,087-$51,129). Assuming no carry-over effects, letrozole yields 0.264 QALYs at a cost of $10,341, for a cost per QALY gained of $39,098 (95% confidence interval, $23,968- $83,501).

CONCLUSION

In postmenopausal women with hormone receptor-positive early breast cancer, initial adjuvant treatment with letrozole is cost-effective from the US health care system perspective.

Letrozole: present and future role in the treatment of breast cancer

State of the art hormonal therapy for women with breast cancer has evolved over the last few years. Tamoxifen used to be the gold standard for adjuvant treatment of postmenopausal women with hormone-sensitive early breast cancer and also for patients with metastatic disease in whom hormonal manipulation was considered, but the introduction of third generation aromatase inhibitors has changed this concept. This article discusses the clinical implications of recent trials with one of the aromatase inhibitors letrozole, including pharmacokinetic and pharmacodynamic data as well as recent data on relative benefits and side effects compared with other available hormonal agents. Relevant ongoing clinical-translational trials evaluating this agent are also discussed.

Comparative economic analysis of aromatase inhibitors and tamoxifen in the treatment of hormone-dependent breast cancer

Within the past 2 years three separate groups reported marked improvements in relapse-free survival when trastuzumab was added to adjuvant chemotherapy in patients with HER2-overexpressing breast cancer. Notwithstanding the significance of this molecular target, the discovery of the estrogen receptor (ER) may be of even greater importance. Although tamoxifen has long been considered the hormonal therapy of choice for patients with estrogen-responsive breast cancer, accumulating clinical data suggest the new generation of aromatase inhibitors (AIs) is more effective and less toxic. With the availability of new information, guidelines have been updated and reformulated regarding the use of AIs as first-line hormonal therapy in postmenopausal women with ER-positive breast cancer. This paper, a product of the ongoing advances in oncology, incorporates two distinct, yet important, features of oncology; first, clinical concepts related to hormone-dependent breast cancer and second, pharmacoeconomic evaluation of the antiestrogen tamoxifen and the new generation of antiaromatase agents.

Aromatase inhibitors--socioeconomical issues

With costs of health care in general and for cancer therapy in particular escalating due to implementation of novel compounds, there is an increasing focus on therapy costs in most countries. A common way of assessing therapeutic utility versus cost is by assessing cost per additional life year gained or cost per additional quality-adjusted life year (QALY) gained with a novel therapy. While endocrine therapy in general is associated with low costs, the fact that aromatase inhibitors are administered over several years to each patient in the adjuvant setting, together with the substantial number of postmenopausal breast cancer patients that are candidates for adjuvant treatment with aromatase inhibitors, advocates critical examination of cost-utilities related to implementation of such therapy in the adjuvant setting. While cost-utility estimates for treatment with aromatase inhibitors in the adjuvant setting look favorable, the estimates are sensitive to variations with respect to long-term benefits but also side effects. For patient groups with a low-risk of relapse but also patients with a limited life expectancy due to high age, cost-utility estimates may exceed the upper limits generally proposed for costs per quality-adjusted life year gained.

Cost-effectiveness of letrozole versus tamoxifen as initial adjuvant therapy in postmenopausal women with hormone-receptor positive early breast cancer from a Canadian perspective

BACKGROUND

In the primary core analysis of BIG 1-98, a randomized, double-blind trial comparing 5 years of initial adjuvant therapy with letrozole versus tamoxifen in postmenopausal women with hormone receptor-positive (HR+) early breast cancer, letrozole significantly improved disease-free survival by 19% and reduced the risk of breast cancer recurrence by 28% and distant recurrence by 27%.

METHODS

A Markov model was used to estimate the incremental cost per quality-adjusted life year (QALY) gained with 5 years of initial adjuvant therapy with letrozole versus tamoxifen from a Canadian healthcare system perspective. Probabilities of recurrence and side effects for tamoxifen were based on published results of BIG 1-98 and other published population-based studies. Corresponding probabilities for letrozole were calculated by multiplying probabilities for tamoxifen by estimated relative risks for letrozole versus tamoxifen from BIG 1-98. Other probabilities, costs of breast-cancer care and treatment of side effects, and health-state utilities were obtained from published studies. Costs and QALYs were estimated over the lifetime of a cohort of postmenopausal women with HR+ early breast cancer, aged 60 years at initiation of therapy, and discounted at 5% annually.

RESULTS

Compared with tamoxifen, letrozole yields an additional 0.368 life-years (12.453 vs. 12.086) and 0.343 QALYs (11.582 vs. 11.239). These benefits are obtained at an additional cost of Can$ 8,110 (Can$ 30,819 vs. Can$ 22,709). Cost per QALY gained for letrozole versus tamoxifen is Can$ 23,662 (95% CI Can$ 15,667-Can$ 52,014).

CONCLUSION

In postmenopausal women with HR+ early breast cancer, initial adjuvant treatment with letrozole is cost-effective from the Canadian healthcare system perspective.

Continuing with letrozole offers greater benefits

OBJECTIVE

Tamoxifen has been at the foundation of adjuvant treatment to prevent disease recurrence in postmenopausal women with hormone-responsive early breast cancer. After 5 years of adjuvant tamoxifen therapy, however, options for further treatment are limited. Additional tamoxifen is not indicated, as no further benefit in disease-free survival (DFS) has been observed. The aromatase inhibitor letrozole significantly improves DFS over placebo in postmenopausal women who have completed 4.5-6.0 years of adjuvant tamoxifen.

MATERIALS AND METHODS

This article reviews the data supporting extended adjuvant letrozole therapy.

CONCLUSIONS

Extended adjuvant letrozole has been shown to be particularly effective in patients with node-positive disease, who are at a higher risk for disease recurrence, improving both DFS and overall survival. Extended adjuvant letrozole is associated with a significant increase in self-reported osteoporosis, but no significant increases in fracture, endometrial malignancies, hypercholesterolemia, or cardiovascular events and no worsening of quality of life, making it suitable for long-term use. The ASCO treatment guidelines recommend at least 2.5 years of extended adjuvant letrozole for patients completing tamoxifen therapy, based upon the MA.17 trial follow-up period. A recent cohort analysis now suggests that extended adjuvant letrozole treatment for at least 48 months is associated with greater benefit. The efficacy of letrozole for up to 10 years following tamoxifen is also being investigated.

Cost-effectiveness of exemestane versus tamoxifen as adjuvant therapy for early-stage breast cancer after 2-3 years treatment with tamoxifen in Sweden

Aromatase inhibitors are rapidly becoming the cornerstone of endocrine treatment for advanced disease and are now also used as adjuvant treatment in early-stage disease. The objective of this study was to assess the cost-effectiveness of adjuvant treatment with exemestane versus tamoxifen for early-stage breast cancer after 2-3 years treatment with tamoxifen in Sweden. The results are based on findings in the Intergroup Exemestane Study (IES). IES was a randomized controlled trial in which postmenopausal women who had received 2-3 years of tamoxifen therapy following primary treatment of early-stage breast cancer, were randomized to either continue on tamoxifen therapy or be switched to exemestane therapy. The results showed a disease-free survival hazard ratio of exemestane relative to tamoxifen in IES of 0.69. A Markov state-transition model was developed to simulate consequences after the end of the clinical trial, and to integrate the trial data with external data on mortality, costs and quality of life specific for Swedish women. The cost per QALY gained was about euro 20,000 in the base case analysis without inclusion of consequences of coronary heart disease. Inclusion of these events increased the cost-effectiveness ratio to about euro 31,000. This means that, based on our assumption, sequential exemestane treatment in early breast cancer is a cost-effective option compared with tamoxifen alone, although more long-term data on overall survival and consequences of adverse events would be valuable to increase the validity of the analysis further.

Cost-Effectiveness of Letrozole in the Extended Adjuvant Treatment of Women with Early Breast Cancer

Adjuvant tamoxifen therapy for 5 years reduces recurrence in hormone receptor positive, post-menopausal women with early breast cancer, but offers no advantage when prolonged to another 5 years, during which the risk of recurrence remains high. Treating patients, who remain disease-free after 5 years of tamoxifen, with letrozole significantly reduces recurrence, regardless of nodal status. This study evaluated the life-time cost-utility of extended adjuvant letrozole therapy in 62-year-old patients from a third-party payer perspective. A Markov model incorporated locoregional, contralateral, and metastatic recurrences. The comparator was placebo. Event rates were based on published trials. Utility values were taken from a clinical trial and published literature. Costs were obtained from published literature, provincial payment schedules, cancer agencies, and drug plans formularies. Resource use reflected Canadian treatment patterns. Robustness of the model was tested using deterministic and probabilistic sensitivity analyses. Extended adjuvant letrozole therapy of a cohort consisting of 50% node-negative and 50% node-positive patients prolonged their lives on average by 0.466 years or 0.267 quality-adjusted life years (QALYs) at an additional cost of Can$8,031 per patient, yielding an incremental cost-utility ratio (ICUR) of $34,058 per QALY. Letrozole was more cost-effective in node-positive than in node-negative patients (Can$26,553 vs Can$46,049 per QALY). Results were robust to variations in age, healthcare costs, and utilities. The degree of confidence that the cost per QALY would be below Can$50,000 reached 100% for node-positive and 77% for node-negative patients. Extended adjuvant letrozole is cost-effective in both node-negative and node-positive patients having ICURs below Can$50,000/QALY.

Letrozole: a pharmacoeconomic review of its use in postmenopausal women with breast cancer

Letrozole (Femara), an aromatase inhibitor that blocks estrogen synthesis by inhibiting the final step of the estrogen biosynthetic pathway, is approved for use in a wide range of breast cancer settings. Randomised clinical trials in postmenopausal women with hormone-responsive early-stage breast cancer have demonstrated that, as adjuvant therapy, letrozole has greater efficacy than tamoxifen. It is also more effective than placebo as extended adjuvant therapy after completion of tamoxifen therapy in these patients. In women with hormone-responsive advanced breast cancer, letrozole is superior to tamoxifen in prolonging the time to disease progression and time to treatment failure in a first-line setting, and is at least as effective as anastrozole and more effective than megestrol for some endpoints (in one of two trials) in a second-line setting. Letrozole is generally well tolerated, and in a health-related quality-of-life analysis from a large clinical trial, patient well-being with letrozole as extended adjuvant therapy did not differ from that with placebo. Modelled analyses from the UK and the US suggest that, in postmenopausal women with hormone-receptor-positive early-stage breast cancer, letrozole is likely to be a cost-effective alternative to tamoxifen as adjuvant therapy; moreover, using letrozole as extended adjuvant therapy after tamoxifen, rather than no further treatment, is also a cost-effective treatment strategy. Sensitivity analyses have shown these results to be robust. In terms of direct healthcare costs, pharmacoeconomic models suggest that letrozole is a cost-effective alternative to tamoxifen as first-line therapy in postmenopausal women with hormone-responsive advanced breast cancer from the perspectives of the UK NHS, the Canadian and Italian public healthcare systems and the Japanese national health insurance system. Incremental costs per QALY or progression-free year gained over tamoxifen were well within the recommended limits for acceptability of new agents that are more effective and more expensive than existing therapies in the UK, Japan and Canada. Modelled analyses from the UK and Canada have also suggested that letrozole is cost effective as second-line therapy for advanced breast cancer in postmenopausal women who have disease progression following anti-estrogen therapy. In conclusion, letrozole is an effective and well tolerated treatment for postmenopausal women with early-stage or advanced hormone-responsive breast cancer. Pharmacoeconomic analyses from UK and North American perspectives support the use of letrozole in hormone-responsive early-stage breast cancer in both the adjuvant and extended adjuvant settings. In addition, other modelled analyses conducted in a variety of healthcare systems across different countries consistently suggest that letrozole is cost effective in advanced treatment settings.