Phase 2 randomized trial of primary endocrine therapy versus chemotherapy in postmenopausal patients with estrogen receptor-positive breast cancer

Role of biologic therapy and chemotherapy in hormone receptor- and HER2-positive breast cancer

BACKGROUND

To review the efficacy of chemotherapy and human epidermal growth factor receptor 2 (HER2)-targeted therapy when used in addition to hormonal therapy for the optimal management of estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-positive (HER2+) breast cancer.

DESIGN

Literature published from January 2003 to March 2008 was reviewed to assess the use of chemotherapy and biologic therapy in addition to hormonal agents.

RESULTS

Aromatase inhibitors (AIs) demonstrated greater effectiveness in the adjuvant setting than tamoxifen for the management of ER+ and HER2+ breast cancer. Evidence of cross talk between HER2- and ER-signaling pathways suggests that combined treatment with HER2 blockade and hormonal therapy may offer clinical advantages beyond those provided by hormonal therapy alone in ER+/HER2+ disease. Combined therapy with trastuzumab plus an aromatase AI significantly improves progression-free survival, response rates, and clinical benefits when compared with AI monotherapy in postmenopausal women. Several large studies demonstrated that trastuzumab significantly improves disease-free and overall survival when given in combination with, or following, chemotherapy, regardless of hormone receptor status.

CONCLUSIONS

HER2-targeted therapy maybe combined with AIs for the treatment of ER+/HER2+ metastatic breast cancer in postmenopausal women. HER2-targeted therapy in combination with AIs for treatment of ER+/HER2+ early breast cancer needs to be prospectively evaluated.

[Neoadjuvant systemic therapy in breast cancer]

Neoadjuvant (preoperative) systemic therapy is a good possibility for the treatment of symptomatic breast cancers of the locoregional stage. Chemotherapy or hormone therapy chosen according to the characteristics of the primary tumor, result in the regression of the tumor in the majority of the cases, favoring breast conserving surgery thereafter. The long-term effects of neoadjuvant systemic therapy are equivalent to that of adjuvant therapy, and the in vivo observed efficiency of the treatment reflects prognosis. Finally, systemic therapy introduced prior to surgery is not delayed by the possible adverse effects of the surgery. Detailed examination of the tumor and the patient is mandatory before starting systemic therapy. Besides breast imaging and histological examinations, staging is necessary. Pathological characterization of the tumor will enhance treatment choice based on the features of chemo- or hormone-sensitivity. For the treatment of chemosensitive tumors, taxane- and anthracycline-based polychemotherapy is the most efficacious. Data on neoadjuvant hormone therapy have been provided by studies on postmenopausal patients. Since the aromatase inhibitors are more efficient than tamoxifen, their use is the first option in this patient population. Among the molecular targeted agents, trastuzumab combined with chemotherapy produces extending therapeutic response rate. Following the completion of the neoadjuvant systemic therapy, breast imaging is required once more before performing breast and lymph node surgery. Postoperative radiotherapy is generally needed. The use of a common language and professional guidelines by the members of the multidisciplinary breast team is a condition for neoadjuvant systemic therapy.

Neoadjuvant Endocrine Therapy in Breast Cancer

Women who suffer from large or locally advanced malignant breast tumors are now commonly treated with preoperative ('neoadjuvant') systemic therapy to improve surgical outcomes and to raise the chances for breast-conserving therapy (BCT). Until recently, chemotherapy was the treatment of choice, and primary systemic endocrine treatment was restricted to medically frail or older women with receptor-positive breast cancer. The development of modern aromatase inhibitors (Als) and their subsequent clinical evaluation in neoadjuvant trials now provides us with an alternative to chemotherapy that is thought to be equally effective, yet considerably better tolerated. Several large prospective trials have compared tamoxifen with the non-steroidal AIs letrozole and anastrozole and the steroidal Al exemestane, with improved outcomes for all AIs in terms of tumor remission and rate of BCT. A number of predictive biomarkers now also allow us to identify those tumors that most likely respond to a certain endocrine regimen.

Facilitating breast-conserving surgery and preventing recurrence: aromatase inhibitors in the neoadjuvant and adjuvant settings

Breast-conserving surgery (BCS) is an attractive option for many patients with early-stage breast cancer, because it provides a better cosmetic outcome than modified radical mastectomy, while reducing surgical morbidity. In patients with large, operable breast tumors who are ineligible for BCS, neoadjuvant therapy is a useful option for reducing the tumor size and for increasing the proportion of candidates for BCS. In patients with endocrine-responsive tumors, neoadjuvant endocrine therapy with either tamoxifen or an aromatase inhibitor (AI; anastrozole, letrozole, or exemestane) provides an alternative to neoadjuvant chemotherapy. Clinical trials have demonstrated the superiority of neoadjuvant AIs over tamoxifen in achieving a clinical response and increasing the frequency of BCS. In addition, adjuvant endocrine therapy with AIs, whether used as initial therapy instead of tamoxifen, in a switching strategy after 2-3 years of tamoxifen, or as extended adjuvant therapy after 5 years of adjuvant tamoxifen, has been shown in several randomized clinical trials to improve disease-free survival, reduce distant metastases and, in some cases, improve overall survival. The availability of the AIs for effective and well-tolerated neoadjuvant and/or adjuvant endocrine therapy represents an important advance in breast cancer treatment, and surgeons should be familiar with these new therapeutic options.

Safely promoting breast-conserving surgery and preventing early relapses with an aromatase inhibitor

Neoadjuvant therapy improves patient outcomes substantially by increasing the rate of breast-conserving surgery. Following primary surgery, women with hormone-sensitive early breast cancer remain at risk for loco-regional and systemic recurrence. The most common relapse event, distant metastases, is associated with the poorest outcomes. As a neoadjuvant therapy, anastrozole, letrozole, and exemestane have been investigated in phase 3 studies and have shown efficacy in this setting. All three aromatase inhibitors (AIs) significantly improved the rate of breast-conserving surgery. As initial adjuvant therapy, the third-generation AIs anastrozole and letrozole more effectively reduce recurrence risk compared with tamoxifen following surgery, especially in the first 2 years, when the risk is greatest. Tamoxifen, once the standard initial therapy, is associated with improved disease-free survival but may be more effective at reducing loco-regional recurrence than distant metastases. Initial adjuvant letrozole therapy has also shown a pronounced reduction in the risk of distant metastases early on in the course of therapy. If AIs are not used upfront, sequential use of exemestane or anastrozole following tamoxifen provides greater protection against relapse than continuing on tamoxifen. Side effects associated with estrogen deprivation of AIs are less serious than those of tamoxifen and are easily managed. Various molecular markers are under study as surrogates to predict response to neoadjuvant therapy, which may in turn predict responsiveness to adjuvant therapy. Surgeons treating breast cancer patients and prescribing endocrine therapy should be aware of all treatment strategies, including neoadjuvant and adjuvant hormonal therapy, and inform their patients of the benefits and the potential side effects. Early and long-term-risk reduction with AI treatment should be discussed with patients, as should the management of common AI-associated adverse events.

Advances in the treatment of breast cancer

Breast cancer is the most commonly diagnosed cancer in American women and is the second leading cause of cancer-related deaths in this population. This review highlights how the use of a multidisciplinary approach to the management of diseases of the breast and the introduction of novel systemic therapies have improved the quality of life and survival in patients with breast cancer.