Predictors of response to second-line endocrine therapy for breast cancer

This study reports on factors predicting response tosecond-line endocrine therapy in 250 patients with breastcancer for which they were assessable for responseby the International Union Against Cancer (UICC) criteria.Clinical details relating to first-line endocrine therapy wereavailable for all patients. We have not includedin this study patients who received first-line endocrinetherapy but did not or have not yetproceeded to second-line hormone therapy – e.g. diedfrom rapidly progressive disease, started chemotherapy for rapidlyprogressive disease, or remained in long-term remission onfirst-line endocrine therapy.One hundred and fifty nine patients (72%) achievedremission (objective response and static disease [OR +SD]) on first-line endocrine therapy with a medianduration of 19 months. For second-line endocrine therapythe remission rate was 53% (132/225) with amedian duration of 15 months. Tumour grade andoestrogen receptor status of the primary tumour wereshown to be independent predictors of response tosecond-line endocrine therapy while response to first-line endocrinetherapy was a predictor of the duration ofresponse to second-line endocrine therapy. In the sub-groupof patients who showed OR or SD toboth first and second-line therapies, there was nocorrelation between the time to progression (TTP) onfirst and second-line therapies.     

Meeting highlights: international expert consensus on the primary therapy of early breast cancer 2005.

The ninth St Gallen (Switzerland) expert consensus meeting in January 2005 made a fundamental change in the algorithm for selection of adjuvant systemic therapy for early breast cancer. Rather than the earlier approach commencing with risk assessment, the Panel affirmed that the first consideration was endocrine responsiveness. Three categories were acknowledged: endocrine responsive, endocrine non-responsive and tumors of uncertain endocrine responsiveness. The three categories were further divided according to menopausal status. Only then did the Panel divide patients into low-, intermediate- and high-risk categories. It agreed that axillary lymph node involvement did not automatically define high risk. Intermediate risk included both node-negative disease (if some features of the primary tumor indicated elevated risk) and patients with one to three involved lymph nodes without additional high-risk features such as HER 2/neu gene overexpression. The Panel recommended that patients be offered chemotherapy for endocrine non-responsive disease; endocrine therapy as the primary therapy for endocrine responsive disease, adding chemotherapy for some intermediate- and all high-risk groups in this category; and both chemotherapy and endocrine therapy for all patients in the uncertain endocrine response category except those in the low-risk group.     

Postmenopausal women who progress on fulvestrant ('Faslodex') remain sensitive to further endocrine therapy

Purpose. This retrospective evaluation of data from two randomized, multicenter trials examined whether tumor responses to further endocrine therapy were seen in postmenopausal women with advanced breast cancer who had progressed on both initial endocrine therapy, usually tamoxifen, and on the estrogen receptor (ER) antagonist fulvestrant ('Faslodex'). Patients and methods. A combined total of 423 patients received fulvestrant 250 mg as a monthly intramuscular injection. After progression on fulvestrant, some patients received another endocrine therapy. Responses to subsequent endocrine therapy were assessed using a questionnaire sent to the trial investigators. Best responses were classified as a complete or partial response (CR or PR), stable disease (SD) lasting 24 weeks, or disease progression. Results. Follow-up data were available for 54 patients who derived clinical benefit (CB, defined as CR, PR or SD) from fulvestrant and who received subsequent endocrine therapy, resulting in a PR in 4 patients, SD in 21 patients, and disease progression in 29 patients. Data were available for 51 patients who derived no CB from fulvestrant and who received further endocrine therapy, resulting in a PR in 1 patient, SD in 17 patients, and disease progression in 33 patients. Aromatase inhibitors were used as subsequent endocrine therapy in >80% of patients. Conclusions. After progression on fulvestrant, patients may retain sensitivity to other endocrine agents. Fulvestrant provides an additional option to existing endocrine therapies for the treatment of advanced or metastatic breast cancer in postmenopausal women, and may provide the opportunity to extend the sequence of endocrine regimens before cytotoxic chemotherapy is required.     

Trend to adjuvant systemic treatment regimens for patients with early breast cancer--meeting highlights of St. Gallen Conference 2005

The 9th International Expert Consensus Meeting on the Primary Therapy of Early Breast Cancer 2005, with 4166 participants from 78 countries, was held in January 2005 in St. Gallen, Switzerland. Its consensus recommendations were summarized in the Annals of Oncology (16:1569-1583, 2005), published on Sept. 7 that year. The Meeting made a fundamental change in the algorithm for selection of adjuvant systemic therapy for early breast cancer. Rather than the earlier approach commencing with risk assessment, the Panel affirmed that the first consideration was endocrine responsiveness. Three categories were acknowledged:endocrine responsive, endocrine non-responsive and tumors of uncertain endocrine responsiveness. The three categories were further divided according to menopausal status. Only then did the Panel divide patients into low-, intermediate-and high risk categories. It agreed that axillary lymph node involvement did not automatically define high risk. Intermediate risk included both node-negative disease (if some features of the primary tumor indicated elevated risk) and patients with one to three involved lymph nodes without additional high-risk features such as HER 2/neu gene over expression. The Panel recommended that patients be offered chemotherapy for endocrine non-responsive disease; endocrine therapy as the primary therapy for endocrine responsive disease, adding chemotherapy for some intermediate-and all high-risk groups in this category; and both chemotherapy and endocrine therapy for all patients in the uncertain endocrine response category except those in the low-risk group.     

Recent perspectives of endocrine therapy for breast cancer

The choice of endocrine therapy for breast cancer depends on the menopausal status and stage of disease. Endocrine therapy remains the first choice and most important component in the treatment of hormone sensitive non-life threatening advanced breast cancer. In premenopausal women with metastatic disease, the combination of a luteinizing hormone-releasing hormone (LH-RH) agonist plus tamoxifen is reasonable as first-line endocrine therapy. In postmenopausal patients with recurrent disease progressing after or during adjuvant tamoxifen, third-generation aromatase inhibitors (AIs) are the preferred first-line endocrine treatment. Many premenopausal and postmenopausal women with hormone responsive breast cancer benefit from sequential use of endocrine therapies at the time of disease progression. Recent clinical trials designs have been implemented, employing AIs as monotherapy in postmenopausal breast cancer patients, as first-line adjuvant therapy, and in sequence either 2-3 or 5 years, with initial tamoxifen. Emerging results from these trials indicate an advantage to patients for any of these strategies, and most international guidelines now suggest the use of an AI in the adjuvant setting in postmenopausal women. The use of endocrine treatment for metastatic and early breast cancer will be reviewed here.     

Breast cancer in men

Most men with breast cancer present with a mass in the breast, the evaluation of which should include a tissue diagnosis. If the presence of invasive cancer is established, adequate local therapy includes total removal of the breast. Most tumors are hormone-receptor positive. In high-risk patients, the use of endocrine adjuvant therapy and/or combined endocrine and chemotherapy should be considered. Patients with estrogen-receptor (ER)-negative disease should be offered chemotherapy. In patients with metastatic disease and ER-positive tumors, initial treatment should be endocrine therapy; systemic chemotherapy should be used in patients who are either hormone-receptor negative or resistant to available endocrine therapies.     

Neoadjuvant endocrine therapy in primary breast cancer: indications and use as a research tool

Neoadjuvant endocrine therapy has been increasingly employed in clinical practice to improve surgical options for postmenopausal women with bulky hormone receptor-positive breast cancer. Recent studies indicate that tumour response in this setting may predict long-term outcome of patients on adjuvant endocrine therapy, which argues for its broader application in treating hormone receptor-positive disease. From the research perspective, neoadjuvant endocrine therapy provides a unique opportunity for studies of endocrine responsiveness and the development of novel therapeutic agents.     

p53 expression status is a significant molecular marker in predicting the time to endocrine therapy failure in recurrent breast cancer: a cohort study

Background Hormone receptor status has been one of the most important factors in predicting the response to endocrine therapy in breast cancer patients. However, half of those patients with estrogen receptor-positive tumors do not respond to endocrine therapy. There have been no universal factors for predicting resistance to endocrine therapy in this population. Recently, p53 status has been extensively used as a predictive factor for response to systemic therapy, because tumor cells lacking p53 function do not respond to systemic therapy due to a failure in apoptosis. We therefore studied the relationship between the efficacy of endocrine therapy and biological factors, including p53. Methods The expression of p53, Ki67, and human epidermal growth factor receptor (HER)2 was examined by immunostaining in the primary tumors of 53 patients who received endocrine therapy for recurrent or advanced breast cancer. The following clinical factors were also analyzed: site treated, disease-free interval, and response to first-line endocrine therapy. To evaluate the significance of these factors, time to endocrine therapy failure (TTEF), or the total duration of sequential endocrine therapies was adopted as representing the clinical outcome. Results The median TTEF was 16.1 months (range, 2.5–89.9 months). Multivariate analysis showed significantly reduced TTEF associated with no response to first-line endocrine therapy (P = 0.006 and P = 0.002 in all patients and in recurrent patients, respectively) and associated with positive p53 expression (P = 0.066 and P = 0.004, respectively). Conclusion p53 expression status was a significant molecular marker as well as the response to first-line endocrine therapy for predicting TTEF in recurrent breast cancer with hormone-sensitive disease.     

Endocrine therapy for advanced breast cancer: A review

Summary More than 45,000 women will die of metastatic breast cancer in the United States in 1991. Endocrine therapy remains a major option for treatment of such patients, and results in complete plus partial response rates of 30% with a median duration of approximately one year. Postmenopausal status, increased age, a prolonged disease-free interval, bone and soft tissue metastases, and positive estrogen and progesterone receptors are all associated with an increased response to endocrine therapy. The use of additive hormonal therapy, specifically antiestrogens, progestins, and aromatase inhibitors, have replaced surgical ablative procedures in the majority of patients; response rates to antiestrogen therapy, progestin therapy, and aromatase inhibitors are similar, but antiestrogens have generally been associated with the most favorable therapeutic index. At present, there is no convincing evidence that either combinations of endocrine therapies or endocrine therapy combined with chemotherapy are associated with an improvement in survival for patients with metastatic disease. Future research efforts directed at defining the molecular mechanisms of endocrine activity should facilitate clinical trials of newer and potentially more effective agents. All patients with metastatic breast cancer should be considered for at least one trial of endocrine therapy provided their metastatic disease is not rapidly progressive or life-threatening.Held at the 14th Annual San Antonio Breast Cancer Symposium, December 5, 1991, and supported by an educational grant from Bristol-Myers Oncology Division, Evansville IN, USA.     

Combined versus sequential chemo-endocrine therapy in advanced prostate cancer: final results of a randomized Southwest Oncology Group study

Cytotoxic chemotherapy has not provided survival benefit in metastatic prostate cancer, although it has been used most frequently in patients with far-advanced, refractory disease. To evaluate the effects of chemotherapy given earlier in the course of the disease, the Southwest Oncology Group (SWOG) performed a randomized trial between September 1982 and October 1986 comparing endocrine therapy (diethylstilbestrol [DES] or orchiectomy) alone followed by cyclophosphamide-Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH) chemotherapy at progression versus initial combined chemo-endocrine therapy. One hundred forty-three patients were registered, and only six were declared ineligible. Patients on the combined chemo-endocrine therapy arm had a slightly higher response rate (63%) compared with endocrine therapy alone (48%). A log-linear model of tumor response and treatment arm adjusted for the stratification factors favored the combination arm (P = .059). Only three of 27 patients on the endocrine therapy alone arm had an objective partial response when crossed over to chemotherapy, while two others had stable disease. Despite the difference in initial response rate, time to treatment failure and survival were identical in the two treatment arms. Seventy-seven percent of patients on the initial endocrine therapy alone arm have died (median survival, 25.6 months) compared with 78% on the chemo-endocrine therapy arm (median survival, 22.0 months). No significant effect of treatment on survival was observed even after adjustment for the stratification variables in a Cox regression model. Exploratory survival analyses with patients on both arms combined did show a marginally significant time to treatment failure and survival advantage for patients treated with DES rather than orchiectomy as initial endocrine therapy. Eighty-six percent of patients treated by orchiectomy have died compared with only 65% of those treated with DES. These data do not support the addition of cytotoxic chemotherapy to initial endocrine therapy in patients with metastatic prostate cancer.     

Endocrine therapy for prostate cancer

Endocrine therapy of prostate cancer has mostly been reserved to patients with advanced stages of the disease. The principle for endocrine treatment of prostate cancer is elimination of stimulatory effects of testicular androgens on the prostate tumour cells. This can be achieved by surgical removal of the testes, by inhibition of pituitary gonadotrohin secretion by GnRH-angonsists or antagonists, by oestrogens or by non-steroidal antiandrogens. Since non-steroidal antiandrogens have fewer side-effects than castrational therapies, there is an increased interest for using endocrine treatment as adjuvant therapy after localized treatment. At least in certain stages of the disease, early hormonal treatment may have survival benefits. The timing of endocrine therapy, the usage of combined androgen blockade and intermittent endocrine therapy will be discussed in this overview.     

How to improve endocrine therapy of breast cancer

The characteristics of endocrine therapy have made it a standard therapy in metastatic breast cancer. Principles for endocrine therapy in the advanced situation are discussed. Recent overviews have shown a definite, although limited effect also in the adjuvant situation. Three possible ways for further improvement of endocrine therapy are discussed. Firstly, the relevance of results with endocrine therapy in advanced disease for the adjuvant situation is challenged. It is suggested that the most meaningful parameter to look for in the metastatic situation might still be the response rate. Secondly, the question is raised of more reliable predictors of effect of endocrine therapy. A possible model for testing in a neoadjuvant setting in operable cancers is suggested. Thirdly, selection criteria for drugs used in endocrine treatment are discussed, in relation to proven efficacy and short-term and long-term toxicity. As endocrine therapy in the future will probably be more frequently used in patients with better prognosis, the aspect of long-term toxicity will be of major concern.     

Fulvestrant ('Faslodex'): extending the reach of endocrine therapy?

An effective option for estrogen receptor-positive breast cancer, endocrine therapy has had a significant role in improving the survival of women with postmenopausal breast cancer for more than 20 years. However, acquired resistance to disease by cancer cells is the repeated cause of relapse for patients. This supplement explores current thinking on resistance to endocrine therapy and, in particular, the potential role for fulvestrant ('Faslodex'), a novel endocrine therapy that possesses a unique mechanism of action.     

Progress and promise: highlights of the international expert consensus on the primary therapy of early breast cancer 2007.

The 10th St Gallen (Switzerland) expert consensus meeting in March 2007 refined and extended a target-oriented approach to adjuvant systemic therapy of early breast cancer. Target definition is inextricably intertwined with the availability of target-specific therapeutic agents. Since 2005, the presence of HER2 on the cell surface has been used as an effective target for trastuzumab much as steroid hormone receptors are targets for endocrine therapies. An expert Panel reaffirmed the primary importance of determining endocrine responsiveness of the cancer as a first approach to selecting systemic therapy. Three categories were acknowledged: highly endocrine responsive, incompletely endocrine responsive and endocrine non-responsive. The Panel accepted HER2-positivity to assign trastuzumab, and noted that adjuvant trastuzumab has only been assessed together with chemotherapy. They largely endorsed previous definitions of risk categories. While recognizing the existence of several molecularly-based tools for risk stratification, the Panel preferred to recommend the use of high-quality standard histopathological assessment for both risk allocation and target identification. Chemotherapy, although largely lacking specific target information, is the only option in cases which are both endocrine receptor-negative and HER2-negative. Chemotherapy is conventionally given with or preceding trastuzumab for patients with HER2-positive disease, and may be used for patients with endocrine responsive disease in cases where the sufficiency of endocrine therapy alone is uncertain. Recommendations are provided not as specific therapy guidelines but rather as a general guidance emphasizing main principles for tailoring therapeutic choice.     

Intermittent endocrine therapy for advanced prostate cancer

Twenty patients with advanced prostate cancer have been treated with an intermittent endocrine therapy schedule. Hormone therapy (diethylstilbestrol in 19 patients and flutamide in 1 patient) was administered until a clinical response was clearly demonstrated and then it was withheld until symptoms recurred. Prior to treatment 17 of 20 patients had bone pain and positive radionuclide scans, two had asymptomatic pulmonary metastases, and one had symptomatic localized disease. Duration of endocrine therapy prior to withdrawal of all treatment ranged 2 to 70 months (median, 10 months). Disease progression occurred 1 to 24 months (median, 8 months) after interruption of therapy. All patients who relapsed had a rapid clinical response following resumption of endocrine therapy. Nine of ten patients rendered impotent by endocrine therapy resumed sexual activity within 3 months of stopping treatment. This data indicates that satisfactory palliation of advanced prostatic cancer can be achieved in selected patients using intermittent endocrine therapy.     

New developments in hormone receptor-positive disease

Of more than one million women diagnosed with breast cancer each year, approximately 700,000 have hormone receptor (HR)(+) disease. Although endocrine therapy has revolutionized breast cancer management and substantially improved outcomes in these patients, the optimal management of these patients remains a significant challenge. For instance, the threshold for adding adjuvant chemotherapy is a topic of continuing debate, and the most effective regimens that include endocrine therapy and chemotherapy are still under debate as well. Tumor markers, such as Ki-67, and host markers, such as cytochrome P450 2D6, are being studied as potential tools to offer more tailored adjuvant endocrine therapy. Current research suggests that luminal A and luminal B cancers are two completely different diseases, and work is being performed to better distinguish between these two disease types and deliver more effective therapy to individual patients. This article addresses these important outstanding issues with respect to HR(+) disease.     

Complete remission following endocrine or combined cytotoxic and hormonal treatment in advanced breast cancer. A retrospective analysis

Among 422 patients with advanced breast cancer treated in a randomized trial we observed 60 complete responses (CR). Sixteen were achieved among 206 patients treated with endocrine therapy alone and 37 among 216 patients treated with concomitant chemotherapy and endocrine therapy. The incidence of CR in women treated with the concomitant modality was higher in those with dominant soft tissue disease, intermediate in those with osseous or pulmonary involvement, and low in patients with liver metastases. Bone was shown to be the organ most responsive to therapy among patients treated with hormonotherapy, while patients with soft tissue metastases had an unexpectedly low rate of complete remission with this modality. The probability of achieving a CR was inversely proportional to the tumor burden in the patients treated with concomitant chemotherapy and endocrine therapy. For complete responders on hormone treatment alone and for those on combined endocrine and cytotoxic therapy, both median time to progression (26 and 29 months, respectively) and survival (52 and 53 months, respectively) were similar and statistically significantly longer than in partial or minor responders. This observation leads us to the conclusion that the hormonal component is the determinant for the length of a CR.     

Comparison of two oestrogen receptor assays in the prediction of the clinical course of patients with advanced breast cancer.

We have examined two new oestrogen receptor (ER) assays--an enzyme immunoassay (EIA) and an immunocytochemical assay (ICA) in a large series of primary breast tumours to compare their potential as predictors of (1) response to endocrine therapy and (2) survival in patients developing advanced breast cancer. Response to endocrine therapy was categorised at 6 months (UICC criteria). ER-ICA appears the better predictor of response to endocrine therapy than ER-EIA. Combining ICA and EIA results did not improve the prediction of response. With both assays patients with ER positive tumours survived longer from the time of diagnosis of advanced disease than those with ER negative tumours. The predictive power of these assay for progression of disease appears slightly better for the ER-ICA.     

Optimizing endocrine therapy for premenopausal and postmenopausal women with breast cancer

The majority of invasive breast cancer patients present with hormone receptor-positive disease, and modulation of estrogen receptor (ER) activation is an essential component of systemic adjuvant therapy for these women. While tamoxifen has traditionally been the primary adjuvant endocrine therapy for all ER-positive women, recent trials evaluating the use of aromatase inhibitors (AIs) have challenged this standard in postmenopausal women, and ongoing trials are examining the optimal use of endocrine therapy in younger women. Issues regarding the optimal approach to endocrine therapy in both pre- and postmenopausal women are examined in this review.     

Neoadjuvant endocrine therapy in breast cancer

The use of endocrine therapy is well established as a primary treatment for locally advanced breast cancer. However, despite the current popularity of neoadjuvant chemotherapy for operable tumours, there is relatively little published evidence for pre-operative endocrine therapy in operable disease, particularly outside of the elderly population. The wider use of aromatase inhibitors (AIs) has encouraged studies that compare the efficacy of AIs with tamoxifen in the neoadjuvant setting, but there remains a lack of comparison of neoadjuvant with adjuvant endocrine therapies. This review discusses the current evidence regarding primary endocrine therapy, along with the factors involved in choosing appropriate patients for neoadjuvant therapy and the current opinions on length of treatment time and measurement of response prior to surgery.