Influence of estrogen receptor status on response of metastatic breast cancer to aminoglutethimide therapy

Randomized trial of tamoxifen versus tamoxifen plus aminoglutethimide as adjuvant treatment in postmenopausal breast cancer patients with hormone receptor-positive disease: Austrian breast and colorectal cancer study group trial 6

PURPOSE

To determine whether the addition of aminoglutethimide to tamoxifen is able to improve the outcome in postmenopausal patients with hormone receptor-positive, early-stage breast cancer.

PATIENTS AND METHODS

A total of 2,021 postmenopausal women were randomly assigned to receive either tamoxifen for 5 years alone or tamoxifen in combination with aminoglutethimide (500 mg/d) for the first 2 years of treatment. Tamoxifen was administered at 40 mg/d for the first 2 years and at 20 mg/d for 3 years.

RESULTS

All randomized and eligible patients were included in the analysis according to the intention-to-treat principle. After a median follow-up of 5.3 years, the 5-year disease-free survival in the aminoglutethimide plus tamoxifen group was 83.6% versus 83.7% in the monotherapy group (P =.89). The corresponding data for overall survival at 5 years were 91.4% and 91.2%, respectively (P =.74). More patients failed to complete combination treatment (13.7%) because of side effects as compared to tamoxifen alone (5.2%; P =.0001).

CONCLUSION

Aminoglutethimide given for 2 years in addition to tamoxifen for 5 years does not improve the prognosis of postmenopausal patients with receptor-positive, lymph node-negative or lymph node-positive breast cancer.

Endocrine therapy in metastatic breast cancer

Endocrine therapy represents a mainstay of effective, minimally toxic, palliative treatment for metastatic breast cancer. Research focusing on the mechanism of action of endocrine agents will provide new insights leading to new hormonal approaches in breast cancer treatment. Development of new agents, especially the 'pure' antiestrogens, is of great interest. Combining endocrine therapy with biologic agents, especially antiproliferative compounds, may lead to more effective treatment in the adjuvant as well as the advanced setting. Tables 4 and 5 summarize response rates to the different groups of endocrine agents used in metastatic breast cancer and doses of commonly used agents, respectively. At present, tamoxifen is the drug of choice as first-line endocrine therapy for metastatic breast cancer with no or minimal symptoms in premenopausal or postmenopausal women. Second-line therapy usually consists of megace. Aromatase inhibitors may be used as second- or third-line therapy in postmenopausal women. In premenopausal women, LHRH analogues are a reasonable choice. The other hormonal agents may be beneficial as salvage therapy. More effective endocrine approaches are under development.

Multicentre cross-over study of aminoglutethimide and trilostane in advanced postmenopausal breast cancer

Trilostane and aminoglutethimide, both given with a physiological replacement dose of hydrocortisone, were randomly allocated to 112 eligible patients with postmenopausal advanced breast cancer. Following treatment failure on either drug the patient continued with the other, if they were in a suitable clinical condition. Sixty-three patients initially received trilostane, of whom 33 subsequently received aminoglutethimide; 49 patients initially had aminoglutethimide and 14 of these then received trilostane. Both groups of patients were comparable in all respects. There was no difference in the response rate to either drug or in the average time to disease progression for the two drugs. Of the 47 patients who received both drugs, nine (19%) showed a response to both, indicating no cross-resistance. Side effects were seen to both drugs in approximately half the patients; these were mainly gastrointestinal symptoms with trilostane and rashes and drowsiness with aminoglutethimide. There was no evidence of cross-over patient susceptibility to side effects.

Multicentre cross over study of aminoglutethimide and trilostane in advanced postmenopausal breast cancer

Trilostane and Aminoglutethimide, each given with a physiological replacement dose of hydrocortisone, were randomly allocated to 72 eligible postmenopausal advanced breast cancer patients; following treatment failure on either drug the patient continued with the other drug, if in a suitable clinical condition. Thirty-eight patients initially received Trilostane of whom 19 subsequently received Aminoglutethimide; 34 patients initially had Aminoglutethimide and seven of these then received Trilostane. Both groups of patients were comparable in all respects. There was no difference in the objective response rate to either drug, Trilostane 11/38 = 29%, Aminoglutethimide 12/34 = 35%, nor in the average time to disease progression for the two drugs, Trilostane 64 weeks, Aminoglutethimide 68 weeks. Of the 26 patients who received both drugs, four showed a response to both suggesting no cross resistance. Side effects were seen to both drugs in approximately half of the patients, but were mainly gastro-intestinal with Trilostane and rash and drowsiness with Aminoglutethimide. There was no evidence of cross over patient susceptibility to side effects.

A multicentre study into the reliability of steroid receptor immunocytochemical assay quantification. British Quality Control Group

Qualitative and semiquantitative assessments of oestrogen receptor and progesterone receptor positivity determined on previously immunocytochemically stained slides were performed by eight independent assessors. Concordance between assessments of steroid receptor status was good (24/25, 96%). Interassessor variations in estimates of positive immunostaining levels were high, varying by between 10 and 75% for individual slides. In 2 cases estimates for the same section ranged between 15% nuclei positive and 90% nuclei positive. Wide variations were also recorded for slides stained for progesterone receptors. Results using an assessment procedure combining staining intensity and percentage positivity estimates were also subject to marked discordance. A computerised image analysis system, also used to assess slides gave results similar to the mean manually determined percentage positivity values. It is suggested that quality control of steroid receptor immunocytochemical quantification be considered and that automated image analysis may represent an accurate and valid means of achieving this.

Recent advances in the treatment of breast cancer

Multidisciplinary efforts have defined a number of prognostic factors and newer strategies to improve the outcome of patients with breast cancer. Conservative surgery has led to improved functional and cosmetic results. The development of a number of effective adjuvant regimens has led to improved survival. In patients with stage I disease, several biological characteristics of tumor have been identified that are associated with increased risk of relapse. A multimodality approach to patients with locally advanced disease and inflammatory cancer has resulted in improved survival. A number of hormonal and cytotoxic drug contaminations can palliate metastatic disease, with a small fraction of patients remaining in extended remission. Dose-intensive programs may lead to further improvements in survival of selected patients with this disease.

New hormonal approaches to the treatment of breast cancer

From this data we can draw several conclusions. Although many new hormonal agents have been developed, there has not been significant improvement in tumor response to single agents over the past several decades. By applying knowledge of tumor ER and PR patient populations can be selected which will have a higher response rate to a given hormonal agent. The approach of combining chemotherapy and hormonal therapy does not appear to significantly alter the course of the disease. Sequential use of Tamoxifen, Premarin, and chemotherapy has been shown in cell lines and animal models to synchronize cells thus increasing the efficacy of chemotherapy. Clinical trials of this synchronization generally show higher response rates including significantly higher CR rates than chemotherapy alone. This approach appears promising and is undergoing further trials. LHRH agonists and tamoxifen are effective in premenopausal women with receptor positive tumors and may replace surgical ablative therapy. Aminoglutethimide is gaining wider acceptance as second-line therapy in postmenopausal ER-positive patients. The new agent 4-OHA may be as effective as AG but with fewer side effects. Toremifine a new antiestrogen and RU486 a new antiprogesterone are undergoing trials. While these new agents appear promising with fewer side effects or greater specificity of action, with the exception of sequential hormone priming/chemotherapy they represent 'the same old approach'. By this we mean manipulation of the hormonal environment of the cell in a continuous fashion acting via the estrogen receptor mechanism to achieve tumor regression. While certain new agents may be more tolerable, it is unlikely that a 'break through' will occur with this approach. The problem is the emergence of cells resistant to hormonal therapy. This occurs either through proliferation of a preexisting resistant clone or development under selective pressure of resistant tumors. Some but not all of these resistant clones have escaped by virtue of not having estrogen receptor present. Others have defects further along the action cascade of estrogen stimulation, such as a defective receptor which cannot bind effectively to the nuclear acceptor sites, or lacking certain other growth factors such as TGF-beta. Whatever the deficit, most patients eventually develop resistant tumors. It is in this direction, toward manipulating later points in the estrogen cascade which our attention should turn to achieve more effective hormonal therapy.

Breast cancer

Breast cancer will affect 1 out of 10 women in the United States and cause 27 deaths per 100,000 women per year. The etiology remains unknown, but the incidence correlates with genetic as well as environmental factors. Screening programs have been shown to prolong the survival by early detection compared with control populations but remain underutilized by physicians and patients. Breast disease can be evaluated by physical examination and mammography and a definitive diagnosis made by needle aspiration, needle biopsy, or excisional biopsy. This allows the patient to participate in the decision regarding mastectomy vs. conservative surgery plus radiation therapy. These two approaches have equivalent survival in selected patients. Patients with locally advanced, nonmetastatic disease benefit from a multidisciplinary approach using preoperative chemotherapy and postoperative radiation therapy. This approach has allowed less disfiguring surgery and improved survival. Preinvasive carcinoma is diagnosed more frequently with the increased use of screening mammography. Local therapy options include simple mastectomy, local excision plus radiation, or local excision alone. The natural history and results of therapy in preinvasive disease are evolving as more data are accumulated. Systemic adjuvant therapy is recommended for all node-positive patients and most node-negative patients with invasive cancer. The specific modality (hormonal or cytotoxic) varies with the subgroup involved. Treatment of metastatic disease to palliate symptoms and prolong survival includes the use of local therapies (surgery and radiation) and hormonal and cytotoxic agents. Most patients benefit, but cure has been unobtainable. Newer approaches utilizing high-dose chemotherapy and bone marrow support with growth factors or autologous transplantation are currently being explored.

Second line hormonal therapy with aminoglutethimide in metastatic breast cancer

One hundred and twenty patients with metastatic breast cancer, whose disease progressed on hormonal therapy with tamoxifen, were treated with aminoglutethimide. The overall response rate was 34% and the median duration of response 9.5 months. Response to aminoglutethimide was achieved in all metastatic sites except lung and brain. Even 25% of patients who had failed to respond to prior tamoxifen did respond objectively to aminoglutethimide. The actuarial survival for all patients at 30 months was 22%. Although initial toxicity was high (70%), side effects of aminoglutethimide were transient, and treatment had to be discontinued in only four patients. The results of this trial confirm that aminoglutethimide is an effective treatment in metastatic breast cancer.

Low-dose aminoglutethimide plus steroid replacement in advanced breast cancer patients resistant to conventional therapies

In an attempt to define the activity and toxicity of low-dose aminoglutethimide plus steroid replacement in advanced breast cancer, we treated 40 patients with aminoglutethimide 500 mg/day + hydrocortisone 50 mg/day. Previous treatment consisted of additive hormones in 29 patients, oophorectomy in 8, and chemotherapy in 32. Among the 37 patients evaluable for response and toxicity, 5 objective responses (16.2%) and 20 stable diseases (54%) were noted. Toxicity, absent in 23 patients (62.1%) and mild in 14, consisted mainly of Grade I (WHO) nausea, drowsiness, cutaneous rash, and dizziness. Responders and patients with stable disease experienced a similar survival (median not reached at 22 months). Aminoglutethimide at low doses appears to be beneficial in patients refractory to conventional therapies even if the objective response rate is low.

Aminoglutethimide and ketoconazole: historical perspectives and future prospects

Aminoglutethimide and ketoconazole, although originally developed as an anticonvulsant and antifungal agent respectively, have both been used to suppress steroid biosynthesis in patients with hormone-sensitive cancer. Aminoglutethimide inhibits several enzymes involved in the synthesis of corticosteroids as well as the aromatase enzyme which converts androgens to oestrogens. About one third of patients with breast cancer show objective improvement with aminoglutethimide, and it may also be of use in the treatment of adrenal carcinoma. However, its toxicity, and the need for concomitant cortisol replacement, severely limit its usefulness. Ketoconazole also inhibits several steroidogenic enzymes, notably C17,20-lyase, and has been used to treat carcinoma of the prostate. Again however, its toxicity and limited efficacy limit its value, although it may be useful in the treatment of certain endocrine conditions such as precocious puberty. Several aromatase inhibitors similar in structure to aminoglutethimide have been developed in an attempt to create more selective and efficient inhibitors. Some of these compounds have been tested in animals but none have as yet been subjected to clinical trials. Attempts to produce imidazole inhibitors of steroidogenesis are less advanced, although one compound (CGS 16949A) has been reported to be a more selective and potent aromatase inhibitor than aminoglutethimide. Selective and effective compounds could be of great value in the treatment of hormone-sensitive carcinoma.

Mechanisms of action of aminoglutethimide as endocrine therapy of breast cancer

During the last decade aminoglutethimide has been recognised as a valuable alternative in endocrine therapy for advanced breast cancer. Although some side effects do occur, most often these are initial effects which subside within a few weeks, and cessation of therapy is not usually indicated. Aminoglutethimide was originally introduced as an inhibitor of steroidogenesis in the adrenal cortex. It was soon recognised, however, that inhibition of the non-glandular aromatase, blocking the conversion of androgenic prohormones to oestrogens, was more important, resulting in decreased blood levels of oestrogens. In this review the role of aromatase inhibition as the only important aspect of the mechanism of action of aminoglutethimide is challenged. Evidence has accumulated during the last few years that aminoglutethimide is a most potent inducer of microsomal enzymes. In addition to the pharmacological implications this has (suggesting important interactions), it also points to the possibility that levels of oestrogens are decreased due to accelerated metabolism of these hormones. Based on new experimental data, and also clinical work with alternative aromatase inhibitors, it appears that the antitumour activity of aminoglutethimide may be due to both aromatase inhibition and accelerated metabolism of oestrogens. This seriously challenges the importance of aromatase inhibition alone as a strategy in endocrine therapy of breast cancer, and furthermore suggests that accelerated metabolism of key hormones is an alternative strategy to be explored.

Clinical pharmacology of aminoglutethimide in patients with metastatic breast cancer

The pharmacology of aminoglutethimide (AG) was studied in two subsequent trials without hydrocortisone supplementation. A total of 79 patients with metastatic breast cancer entered the study, and their plasma and urine samples were analyzed by high-performance liquid chromatography (HPLC). Thirty evaluable patients with a median age of 57 years (range, 37-79) were treated with the standard dose of 1000 mg/day, and 37 evaluable patients with a median age of 59 years (range, 35-79) received 500 mg/day. The median follow-up in the two groups was 5 months (range, 1-16) and 4 months (range, 1-21), respectively. After the first oral dose of 500 mg, peak plasma concentrations of AG were observed 1-4 h after administration in 15 patients. The elimination half-life was 10.1 +/- 1.7 h (mean +/- SD) after initial dosage; it decreased significantly to 6.9 +/- 1.2 h after 8 weeks of treatment. The area under the curve of AG concentrations was 92.5 +/- 14.2 micrograms/ml x h. The total clearance rate was 5.5 +/- 0.9 1/h and the volume of distribution was 80 +/- 111. About 23% of the drug was excreted unchanged in the urine. The major metabolite, N-acetyl-AG (AAG), had the same half-life as AG. A comparison on day 7 of treatment revealed that doses of 1000 and 500 mg yielded AG plasma concentrations of 9.0 +/- 1.2 and 4.5 +/- 0.5 micrograms/ml, respectively. After 1 month of treatment, however, AG plasma levels of 6-7 and 4-5 micrograms/ml were observed, respectively. A 50% reduction of dose, therefore, resulted in only 30% lower AG levels during continuous treatment. Apparently, the induction of metabolism is of greater importance in standard-dose than in lower dose treatment. The plasma concentrations of AG did not bear a relationship to the clinical response.

On the role of additive hormone monotherapy with tamoxifen, medroxyprogesterone acetate and aminoglutethimide, in advanced breast cancer

We analyzed the results of clinical studies on the therapeutic efficacy of hormone monotherapy with tamoxifen, medroxyprogesterone acetate, and aminoglutethimide in metastatic breast cancer, which were published between 1971 and 1986 and involved altogether 7000 patients. The overall response rates in patients treated with these hormonal single agents at various dose levels ranged from 31%-42%. When only estrogen receptor-positive patients were considered, the response rates lay between 41% and 54% in groups which were treated with the antiestrogenic agents tamoxifen or aminoglutethimide. The duration of remission was 12 months for tamoxifen- and aminoglutethimide-treated women, whereas medroxyprogesterone acetate effected remissions lasting from 6-16 months. The overall mean survival from start of therapy in tamoxifen- and aminoglutethimide-treated groups was 20 months, whereas information concerning this therapeutic parameter was available only in a minority of medroxyprogesterone acetate-treated groups. With respect to the response by site of metastatic lesions, all three agents caused a significantly higher degree of remissions in the soft tissue as compared to visceral disease.

Aminoglutethimide as second-line hormonal therapy in advanced breast cancer: response and toxicity

Seventy-nine postmenopausal patients received aminoglutethimide (AG; 750 mg daily) and hydrocortisone therapy for metastatic or locally recurrent breast cancer following the failure of other hormonal therapy. Fourteen of 64 patients, tolerating the drug and assessable for response, achieved a complete or partial response. Disease stabilisation occurred in a further 2 patients giving a response rate of 25% in these patients. Median duration of response was 10 months. Response rates to AG were not significantly different whether or not there had been a response to previous hormonal therapy but a trend to higher response rates in ER rich tumours was observed. Those with a longer interval from first relapse to the start of AG appeared more likely to respond. Side-effects were noted in 35 patients overall (44%) and in 70% of those over the age of 65 years. Treatment was discontinued because of toxicity in 10 patients and there was one death due to agranulocytosis. AG is active in postmenopausal breast cancer following failure of first-line hormonal therapy, toxicity limiting its use earlier in the disease.

Aminoglutethimide and medroxyprogesterone acetate in the treatment of patients with advanced breast cancer. A phase II study of the Association of Medical Oncology of the German Cancer Society (AIO)

One hundred twenty-eight women with advanced metastatic breast cancer were treated with a combination of aminoglutethimide (AG) (1000 mg orally, daily) and medroxyprogesterone acetate (MPA) (1500 mg orally, daily for six weeks and thereafter 500 mg orally, daily; omitting cortisone substitution). AG/MPA did not lead to side effects other than those described under AG or MPA monotherapy. Mental and personality changes seem to be more severe and frequent under combined therapy than under monotherapy. Impairment of mental functions, depressive syndromes, fatigue, ataxia, skin rash, and transient increase of gammaglutamyl transferase appeared and disappeared within the first 4 to 6 weeks of treatment. Objective remissions of at least 3 months duration from initiation of therapy were seen in 21 of 128 patients (21.9%) (3.9% complete remission [CR], 18% partial remission [PR]). A no change (NC) status occurred in an additional 25.8%. The remission duration (mean and range) was 19 (10.5-54) for CR, 16.5 (4.5-52+) for PR and 6 (3-27) months for NC patients. The highest response rate was registered for patients with only bone involvement (PR, 11; and NC, 11 of 26 patients). There was a distinct correlation of response to prior systemic treatment, receptor status of the primary tumor, disease-free interval, menopausal status, age and condition of the patient. PR was obtained in 4 of 20 patients with receptor-negative primary tumors. These results justify a prospective trial comparing AG/MPA with other forms of endocrine therapy in selected patient subgroups.

Aminoglutethimide in the treatment of premenopausal patients with metastatic breast cancer

Eighteen premenopausal patients with progressive metastatic breast cancer were treated with aminoglutethimide (AG)/cortisone. All patients received 1000 mg AG per day in combination with 2 X 25 mg cortisone acetate. Complete (CR) and partial remissions (PR) were achieved in 27.8%, a no change (NC) in 16.7% and progressive disease (PD) in 55.5% of all cases. The clinical results show that AG/cortisone acetate is effective in the therapy of premenopausal as well as postmenopausal patients with metastatic breast cancer. One hormone receptor negative tumour completely responded. Contrary to postmenopausal patients whose low oestradiol levels continuously decrease, oestradiol levels in premenopausal patients were not influenced by treatment. A distinct suppression of the ovarian activity does not occur. Thus concluding, a mechanism--at least partially different from those in the postmenopause and not necessarily of endocrine nature--must exist in the premenopause. We, therefore, no longer think it justified to assert that the therapeutic effect of AG is merely based on medical adrenalectomy.

Aromatase in breast cancer and the role of aminoglutethimide and other aromatase inhibitors

Approximately one third of human breast carcinomas are hormone dependent and regress upon reduction of circulating estrogen levels. Traditional treatment strategies utilized surgical ablative methods to lower estrogen concentrations as treatment of breast cancer. Currently, investigative emphasis is focused upon development of highly specific antiestrogens and inhibitors of estrogen production. The enzyme, aromatase, as the terminal step in estrogen biosynthesis, is a logical target for blockade with potent and specific inhibitors. The earliest available aromatase antagonist, aminoglutethimide, suppresses estrogen production to the same extent as surgical ablation and is an effective treatment for breast cancer. Aminoglutethimide, however, blocks other cytochrome P-450-mediated steroid hydroxylations, requires concomitant glucocorticoid administration, and is associated with initial side effects. Several more specific inhibitors by destroying aromatase irreversibly as well as by competitive inhibition. One of these, 4-hydroxy-androstenedione, has been intensively studied in animals and is undergoing clinical trial. New data regarding these inhibitors further emphasize the key role of aromatase in estrogen production and the practical utility of blocking this enzyme.

Could aminoglutethimide replace adrenalectomy?

Could aminoglutethimide replace adrenalectomy? This question has already been answered in clinical practice in the United Kingdom, for surgical adrenalectomy has declined markedly in frequency as new hormonal therapy has appeared. An optimal assessment of an endocrine therapy can only be made in previously untreated patients because of the heterogeneity of previously treated populations. Thus aminoglutethimide (AG) and adrenalectomy have been compared for previously untreated and treated populations. Because AG is commonly called 'medical adrenalectomy', this article will review and compare aminoglutethimide therapy with surgical adrenalectomy and make the case that surgical adrenalectomy is no longer indicated in the management of breast cancer.

Additive hormonal therapy in women with advanced breast cancer

A great deal of work has been done over the last decade in the assessment of additive hormonal treatment approaches in women with advanced breast cancer. This work has been prompted by a number of factors which include: (1) the introduction of new hormonal agents, (2) increased knowledge of the physiologic actions of several hormonal agents, (3) the development of hormonal receptor assays to better predict the probability of hormonal responsiveness in a given patient, and (4) the apparent plateau in efficacy of cytotoxic chemotherapeutic approaches. The hormonal agents that have been studied most extensively in the recent past include tamoxifen (an antiestrogen), aminoglutethimide (an aromatase inhibitor), and medroxyprogesterone acetate (a progestin). In postmenopausal women, several agents exist that appear about equal in efficacy; but, currently, tamoxifen appears to be preferred as the initial hormonal treatment, primarily because of its low incidence of side effects. Studies involving combination hormonal therapy have produced interesting results, but further work is needed to establish superiority over tamoxifen alone. In premenopausal women, tamoxifen does have antitumor activity in some patients but has not been established as a replacement for oophorectomy. Properly conducted comparative trials will remain essential for the determination of the proper place of newer hormonal therapy approaches in clinical practice.

Aminoglutethimide induced hormone suppression and response to therapy in advanced postmenopausal breast cancer

Eighty-one postmenopausal women with advanced breast cancer were studied for the effects of treatment with aminoglutethimide (AG) plus hydrocortisone on peripheral hormones and response to therapy. There were 40 responders (R) and 41 non-responders (NR) at 3 months from the start of treatment. Plasma oestrone concentrations were higher in non-responders at 1 and 2 months after starting AG (Means: NR 106 +/- 50, R 84 +/- 26 pmol l-1, P less than 0.05; highest value NR 121 +/- 51, R 99 +/- 24 pmol l-1, P less than 0.05). High oestrone levels were correlated with bulky liver secondaries, but not with age, tumour-free interval, time from last menstrual period, time from relapse to start of AG or body weight. Non-responders had higher mean prolactin levels on treatment (prolactin less than 500 mIUl-1 in 14/40 NR, 2/35 R, P less than 0.01). High oestrone or prolactin levels were present in 28/41 NR and 6/40 R (P less than 0.001). Dehydroepiandrosterone sulphate suppression did not differ between R and NR. The differences in peripheral endocrine environment in non-responding patients suggest that oestrogen metabolism may differ in non-responding patients and that sub-groups could be selected for rational endocrine therapy.

Treatment of advanced breast cancer with aminoglutethimide after therapy with tamoxifen

Thirty-eight metastatic breast cancer patients were treated with aminoglutethimide. All patients had progressive metastatic disease following initial response to Tamoxifen therapy. Thirty-two patients were evaluable for response, of these, two patients (6%) had complete remission, 13 patients (41%) had partial response, and six patients (19%) had stable disease. Eleven patients (34%) had progressive disease. The most common side effects were transient skin rash, lethargy or dizziness. Four patients' (11%) treatment was discontinued because of either skin rash or dizziness within the first two weeks of the study. These data show that aminoglutethimide is an effective agent following tamoxifen therapy.

Medical adrenalectomy in patients with advanced breast cancer

Medical adrenalectomy, consisting of aminoglutethimide plus either dexamethasone or hydrocortisone, was administered to 53 women with advanced breast cancer. Sixteen (30%) patients had an objective response, five patients had stabilization of disease, 26 patients demonstrated progression of disease, two patients did not adhere to protocol, and four patients had severe toxicity necessitating discontinuation of the drugs. Medical adrenalectomy accurately predicted response to subsequent surgical adrenalectomy in 23 patients. Estrogen receptor (ER) data accurately predicted response (eight of nine (89%) ER-positive patients responded) or failure (only two of 14 (14%) ER-negative patients responded) to medical adrenalectomy. Thirty (of 51 women adhering to protocol) had no toxicity. Therefore, it appears that medical adrenalectomy is safe, usually well tolerated, and can accurately predict response to surgical adrenalectomy. Its use should be limited to ER-positive patients, and it may totally supplant surgical adrenalectomy in the management of advanced breast cancer.

Suppression of estrogens with aminoglutethimide and hydrocortisone (medical adrenalectomy) as treatment of advanced breast carcinoma: a review

Fifty to sixty percent of postmenopausal women with estrogen receptor positive metastatic breast cancer respond objectively to surgical ablation of the pituitary or adrenal glands. Several investigators have recently developed medical alternatives to surgical ablative therapy for these patients. This review describes one of these strategies, the inhibition of estrogen synthesis with the enzyme inhibitor aminoglutethimide (AG). Aminoglutethimide blocks several cytochrome P-450-mediated steroid hydroxylation steps including those required for cholesterol to pregnenolone conversion and for the aromatization of androgens to estrogens. In women with metastatic carcinoma, a regimen including 1,000 mg of AG and 40 mg of hydrocortisone as replacement glucocorticoid was administered daily. Clinical studies revealed a 32% objective response rate to AG-HC in unselected patients, and a 52% response in women with estrogen receptor positive tumors. Randomized trials revealed that AG-HC produced objective regression as frequently as surgical adrenalectomy (Ag-HC + 53% vs. surgical adrenalectomy (43%, p = NS), and as surgical hypophysectomy (AG-HC 47% vs. hypox 21%, p + NS). Comparison of AG-HC administration with antiestrogen treatment suggested an equal rate of response to either therapy. Preliminary data document responses to AG in antiestrogen-resistant patients. Current studies do not allow precise recommendations regarding the sequence of use of antiestrogens and AG-HC.

Oestrogen receptors and the response of metastatic breast cancer to aminoglutethimide or tamoxifen

Oestrogen receptor (ER) measurements in metastatic and primary tumours from patients with breast cancer have been correlated with the objective tumour response to treatment with aminoglutethimide (24 patients) or tamoxifen (39 patients). The rate of response in patients with ER-positive tumours (aminoglutethimide 69%, tamoxifen 70%) was significantly greater than in those with ER-negative tumours (aminoglutethimide 9%, tamoxifen 10%). Five of six patients showing an objective response to tamoxifen treatment responded later to aminoglutethimide, whereas only two of 12 patients who had not responded to tamoxifen responded later to aminoglutethimide. Toxicity rates were low for tamoxifen (5%), and reasonably low with aminoglutethimide (20%). Because of the low toxicity of tamoxifen, this agent could reasonably be used in breast cancer regardless of the availability of tumour ER measurements. The use of aminoglutethimide could be based either on the presence of ER in the tumour or on the response to previous tamoxifen therapy.

Aminoglutethimide therapy in advanced breast cancer

Aminoglutethimide inhibited adrenal steroid synthesis, as assessed by serial estimations of plasma dehydroepiandrosterone sulphate in ten patients with advanced breast cancer. There was a favourable response in seven out of the ten patients, and in four there was an objective remission using UICC criteria. Favourable responses were more common in patients who had shown similar responses to previous endocrine therapy, especially a response to tamoxifen. Side effects were mild: two patients exhibited a drug sensitivity reaction, but neither required cessation of therapy. Adrenal suppression by aminoglutethimide is effective and well tolerated, and is therefore preferable to surgical adrenalectomy in the treatment of advanced breast cancer.