Preoperative endocrine therapy for breast cancer

Endocrine Therapy for Breast Cancer: A Model of Hormonal Manipulation

Oestrogen receptor (ER) is the driving transcription factor in 70% of breast cancer. Endocrine therapies targeting the ER represent one of the most successful anticancer strategies to date. In the clinic, novel targeted agents are now being exploited in combination with established endocrine therapies to maximise efficacy. However, clinicians must balance this gain against the risk to patients of increased side effects with combination therapies. This article provides a succinct outline of the principles of hormonal manipulation in breast cancer, alongside the key evidence that underpins current clinical practice. As the role of endocrine therapy in breast cancer continues to expand, the challenge is to interpret the data and select the optimal strategy for a given clinical scenario.

Surgery is associated with lower morbidity and longer survival in elderly breast cancer patients over 80

As breast cancer is the most frequent cancer in the elderly with a peak incidence of 1 in 10 by the age of 80, it is important to establish optimum therapy in this group. We conducted a case note-based retrospective study of all elderly primary breast cancer patients aged 80 and above between 1992 and 2002. The type of treatment, complications, disease progression, recurrence, and overall survival were recorded. In all 110 patients aged 80 and above were treated for primary breast cancer, with 32 patients having advanced disease. Of these, 62 patients received primary endocrine treatment. 48 patients underwent surgery with 30 patients undergoing mastectomy. At follow-up, 34 patients suffered disease progression in the primary endocrine treatment group and three patients had local recurrence in the surgical group. The Kaplan-Meier analysis revealed significantly better survival in the surgical treatment group when compared with the primary endocrine treatment group, both in the early disease (n = 41; median survival: 71 months; compared to n = 37; median survival: 42 months; p = 0.0002) and the advanced disease (n = 7; median survival: 48 months; compared to n = 25; median survival: 36 months; p = 0.03). Prompt surgery and adjuvant treatment can decrease relapse and improve survival even in patients older than 80 years.

Endocrine therapy for breast cancer: an overview

Endocrine therapy for breast cancer has been established in the adjuvant treatment for primary disease and in the treatment of advanced disease. The ER remains the best predictor of response although other factors exist and need to be identified. Pharmacological manipulation has been replacing ablative procedures. Tamoxifen used to be the most popular agent of choice and promising new agents include the pure anti-oestrogens and the third generation selective aromatase inhibitors. Ongoing and future studies will optimise treatment in established areas and will exploit its potential roles in preoperative use and chemoprevention.

Management of early breast cancer in the elderly

Breast cancer is the most common malignancy in women with an age related increase in incidence ranging from 1 in 50 at age 50 to 1 in 10 at age 80. This is particularly significant in view of the changing demographics in the western population, characterised by an aging population and increased life expectancy. However in spite of favourable prognostic factors and less aggressive biological behaviour, elderly breast cancer patients receive less aggressive treatment when compared with their younger counterparts. Appropriate treatment should be offered depending on physiological reserve and comorbidities. Primary endocrine treatment has been shown to be associated with significant morbidity in terms of disease progression. Prompt surgery and adjuvant treatment can decrease relapse and improve survival. Radiation therapy is shown to decrease local relapse and chemotherapy may have a role in a select group of patients with adverse prognostic factors. With incidence of breast cancer bound to increase in the elderly population, it is essential to establish optimum therapy in this cohort of patients as studies reveal good outcome from standard treatment.

Evidence-Based Neoadjuvant Endocrine Therapy for Breast Cancer

Breast cancer is the most common malignancy among women in Western countries. The management of patients with nonmetastatic breast cancer with primary endocrine therapy has evolved dramatically in the past decade. Neoadjuvant treatment has been used to turn inoperable tumors into operable tumors and also to downstage tumors. Hormone receptor-positive breast tumors exposed to neoadjuvant chemotherapy have lower rates of pathologic complete response than hormone receptor-negative tumors. Recently, clinical trials showed an increased response rate and a higher rate of breast-conserving surgery with aromatase inhibitors compared with tamoxifen. Exploratory data suggest that predictive markers of response include a higher estrogen receptor expression level and a negative HER2 status. With the introduction of "biologic" agents and surrogate markers like Ki-67, several studies are evaluating which patients are more likely to respond to preoperative hormonal agents. This review summarizes recent data on neoadjuvant endocrine therapy for breast cancer and the implication of predictive markers of response into clinical practice and future research.

Using aromatase inhibitors in the neoadjuvant setting: evolution or revolution?

Despite improvements in the management of patients with early breast cancer, the prognosis for women with locally advanced breast cancer (LABC) remains poor. The potential goals of neoadjuvant treatment for this disease include down-sizing tumours to allow breast conservation as well as the possibility of improving survival rates. Neoadjuvant treatment was initially dominated by chemotherapy, which increased rates of breast conserving surgery, but to date has demonstrated no survival benefit over standard adjuvant chemotherapy. With recent advances in endocrine therapy, and rapid and routine assessment of predictive factors of response such as estrogen (ER), progesterone (PR) and Her2 nu receptor status, endocrine therapy has come to the forefront of research investigating a neoadjuvant alternative to chemotherapy. Early studies of neoadjuvant endocrine therapy mainly evaluated the role of tamoxifen in the treatment of elderly postmenopausal women with LABC who were unselected for ER/PR status and were unsuitable for either surgery or chemotherapy. Response rates in these patients were found to be inferior to those traditionally obtained from trials with neoadjuvant chemotherapy. Paralleling the superiority that third-generation aromatase inhibitors have shown over tamoxifen in the metastatic and adjuvant settings however, AIs have also demonstrated superiority in the neoadjuvant setting. Recent studies have shown response rates for neoadjuvant treatment with aromatase inhibitors in carefully selected hormone receptor positive patients to be comparable to those seen with neoadjuvant chemotherapy. This is particularly important as hormone receptor positive tumours have repeatedly been shown to have lower response rates to neoadjuvant chemotherapy than hormone receptor negative tumours. Neoadjuvant endocrine treatment with aromatase inhibitors has therefore evolved from being an experimental effort to palliate women with LABC unsuitable for surgery or chemotherapy, to representing a viable and possibly preferred alternative for postmenopausal women with hormone receptor positive large tumours or LABC. Further benefits of neoadjuvant trials include allowing the study of predictive biomarkers of disease in order to provide insight into therapy resistance and sensitivity, and identifying promising systemic therapies for additional testing in larger adjuvant trials.

Expression of prolactin receptor mRNA in oestrogen receptor positive breast cancers pre- and post-tamoxifen therapy

AIM

Previous in vitro studies have shown that tamoxifen down-regulates prolactin receptors in breast cancer cells. The aim of this study was to determine whether similar changes might provide the basis for a predictive test in patients.

METHODS

Biopsy specimens were obtained from 28 post-menopausal women immediately before initiation of treatment with tamoxifen (20 mg daily) and after treatment for 7 days. Prolactin receptor mRNA, determined by reverse-transcription polymerase chain reaction, was then expressed relative to 18S ribosomal RNA.

RESULTS

There was good evidence for a decline in receptor expression in response to treatment with tamoxifen in the whole group (p = 0.036) but with a particularly marked decrease (>60%) in a sub-group of 11 patients. No clear correlation with tumour type or grade, or with several other markers (progesterone receptor, c-erb B-2, pS2, or Bcl-2) was apparent.

CONCLUSION

Tamoxifen reduces expression of mRNA encoding the prolactin receptor in a sub-group of breast tumours and might provide the basis for a predictive test for tamoxifen therapy.

Role of aromatase inhibitors in the treatment of breast cancer

BACKGROUND

Estrogens play a pivotal role in the development of breast cancer. Endocrine therapy based on estrogen blockade is a well-established treatment in hormone-dependent breast cancer. Tamoxifen citrate has long been considered the "gold standard" due to its relative safety and efficacy. Aromatase inhibitors are anti-estrogen agents that target specifically the aromatase enzyme, which is the final step in the estrogen production. The first use of aromatase inhibitors in breast cancer was associated with adverse effects such as rash, drowsiness, and adrenal-gland suppression. Newer third-generation agents are emerging as potential alternatives to tamoxifen, associating clinical efficacy with a more favorable safety profile.

OBJECTIVES

The aim of this article is to review the mechanisms of actions pharmacology, adverse effects, and clinical applications of the aromatase inhibitors available in the United States.

METHODS

The terms breast cancer or neoplasia, aromatase, aromatase inhibitors, third-generation, endocrine therapy, and antiestrogens were used to search MEDLINE for English-language studies published between 1966 and April 2004. A parallel search was performed at the corresponding Web site of each of the aromatase inhibitors available in the United States. Identified publications relevant to the article objectives were selected.

RESULTS

Anastrozole, letrozole, and exemestane are the 3 commercially available aromatase inhibitors approved by the US Food and Drug Administration for the treatment of hormone receptor-positive breast cancer in postmenopausal women. They have been used in several clinical scenarios, including advanced and early disease and chemoprevention, and in the neoadjuvant setting. There is evidence that aromatase inhibitors are more effective and tolerable than tamoxifen in advanced breast cancer and in the neoadjuvant setting. Based on the results of a large, randomized trial, their use in early disease and in chemoprevention is also promising. Aromatase inhibitors appear safe; however, the long-term safety profile is still unknown, especially concerning bone metabolism.

CONCLUSION

Third-generation aromatase inhibitors are a new treatment modality in estrogen and/or progesterone-receptor positive breast cancer. Although they are replacing the "classic" antiestrogen agents used in metastatic breast cancer, their benefit in early disease and as chemopreventive agents is not completely clear. Ongoing clinical studies should become available within the next few years and will provide additional recommendations for their use in patients with breast cancer.

Letrozole for the management of breast cancer

Letrozole, a third-generation aromatase inhibitor, has been the only aromatase inhibitor to date to show unequivocal superiority to tamoxifen as first-line treatment of metastatic postmenopausal breast cancer. The superiority of letrozole compared with tamoxifen was also reflected in the neoadjuvant setting, in both estrogen receptor-positive and estrogen receptor-unknown patients with differing HER-2 status. Currently, studies are being performed in the adjuvant setting, which will provide important data on the long-term safety of letrozole and help determine its suitability as a chemopreventive agent in healthy women at risk of developing breast cancer. Nevertheless, the superior clinical efficacy and survival data of letrozole suggest that it has the potential to displace tamoxifen as the gold standard in breast cancer treatment in the coming years.